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CatalogIntroductionⅠ Types of Relay    1.1 What is a SPDT Relay    1.2 What is a DPDT Relay    1.3 The Symbol of DPDT RelayⅡ 12V SPDT Type RelayⅢ SPDT type Relay Pins ConfigurationⅣ How does a DPDT Relay Work?Ⅴ How to Connect DPDT Relays in the CircuitⅥ Uses of a DPDT RelayⅦ How to Connect a DPDT Relay in a CircuitSummaryIntroductionA relay is a switch that is controlled by an electrical circuit. It has a sequence of input and control signals because it is a circuit. It operates by receiving an input signal from connected input power sources that function as normal switches. This article will show you how to wire dpdt relays in a circuit. It will also assist you in comprehending how the dpdt relay operates and its applications.Quick DPDT relay component introduction and demonstrationⅠ Types of RelayElectrical Relay Switches of many varieties are available on the market.SPST – Single Pole Single ThrowDPST – Double Pole Single ThrowSPDT – Single Pole Double ThrowDPDT – Double Pole Double ThrowHowever, the most commonly utilized Relays are SPDT Relays and DPDT Relays, both of which function as electromechanical switches.1.1 What is a SPDT RelayA single pole double throw (SPDT) relay has two coil terminals and a common terminal, followed by two switching terminals N/O (Normally Open), N/C (Normally Closed) (Normally Close)If there is insufficient DC supply in the coil terminals, the relay displays the idle situation, which is represented by the common terminal attached to the N/C terminal. When the coil receives the needed DC supply, it becomes magnetically energized, and the magnetic flux force attracts the common terminal lever, which is composed of iron and connects to the N/O terminal, causing the N/C to open.1.2 What is a DPDT RelayA dpdt relay is an electromagnetic device used in electric motors. It is also known as a Double(D) Pole(P) Double(D) Throw(T) relay. There are two inputs to a dpdt. Furthermore, each piece of data has two outputs.This DPDT Relay has two coil terminals, two independent common terminals C1, and C2, and two Normally Open (N/O1, N/O2), and two Normally Close (N/C1, N/C2) terminals. It makes two different connections and controls the coil with a single control signal.If there is no bias at the coil, the relay remains in an idle state, with common terminals connected to N/C terminals. When DC bias arrives at the coil, it magnetically energizes and attracts common terminal levers, forming a connection between common terminals and N/O terminals. The N/C terminals now become open and work with their pairs.1.3 The Symbol of DPDT RelayLet's look at the DPDT Relay connection diagram to better comprehend its operation.The coil of the relay is connected to a battery series with a switch designated S1 in this diagram. Two distinct circuits are linked by two distinct input and output pairs. Battery1, LED1, and LED2 make up Circuit 1. Circuit 2 is made up of batteries 2, LED 3, and LED 4.When switch S1 is turned off, the relay's coil is not energized, so LED2 and LED4 are turned on since they are linked to NC terminals, but LED1 and LED3 are turned off.When the switch S1 is turned on, the coil of the relay is activated, which turns off the LED2, and LED4, and turns on the LED1, and LED3.DPDT relays are found in sophisticated electronic circuits and gadgets.The DPDT relay is highly intriguing and may be utilized in a variety of scenarios, including altering the direction of a motor, as seen in the illustration below. It has two terminals and four connectors, and it is equivalent to two Single Pole Double Throw SPDT relays.Ⅱ 12V SPDT Type RelayThis is a 12V SPDT relay (Single Pole and Double Throw). Normally, I utilize these types of relays to manage alternating current loads. The specifications for the relay are displayed on the top. This relay can be controlled using 12VDC, which is the voltage utilized to energize the relay coil. This voltage is fully isolated from the voltage supplied to the relay's Common and typically closed or normally open contacts.It can handle AC load currents of up to 7Amps at 250VAC, 10A AC loads at 125VAC, and 12A AC loads at 120VAC. This relay can also manage DC loads with a voltage of up to 28VDC and a current of up to 10Amps.Ⅲ SPDT type Relay Pins ConfigurationEven if you use a 5v Relay, the pin configuration of these sorts of relays is the same.This relay has a total of 5 pins or contacts, with 3 on one side and 2 on the other. The center of the three contacts on the left side is the common contact, while the other two are coil contacts. On the right, there are two contacts, NC and NO. The normally closed contact is NC, and the normally open contact is NO. The coil connections are electrically insulated from the Common, Normally Closed, and Normally Open contacts. In other words, no physical connection exists between the coil contacts and the other relay connections.Connect 12V and GND to the coils relay coil connections to test this relay. Because the relay coil has no polarity, it makes no difference whether the side of the coil is connected to the 12VDC and which side is connected to the GND.Ⅳ How does a DPDT Relay Work?When manual switching is unavailable, a relay-insulated coil automatically flips changeover switches. As a result, it functions as a control circuit. When electricity is applied, relays frequently use components that resemble transistors to carry the electrical loads. However, there is a type known as electromechanical relays. These relays are simple to understand.The relays use low voltage to convert the electromagnet into a magnetic field. It also contains a contact switch for controlling the magnetic circuit. When the maintained course is within the magnetic field, the relay mostly operates as if a button is flipped with the contacts in place.Because of the operating principles of a household switch, it will always remain in the state you left it. If you turn it on, it will remain on until you turn it off, and vice versa. A relay coil, on the other hand, operates differently since its basic activities need electromagnetic actions. The electrical switches are relaxed when the magnet present is in a field during deactivation. It says that if the current ratings are off, the external circuit will switch on; else, the device would fail.A dpdt relay is a type of relay with two poles. As a result, this double pole can toggle the circuit on both sides. Furthermore, the dpdt has a double throw. Because of the double-throw, the course may simply switch between wires rather than just control output by turning it on and off using electric power systems.Ⅴ How to Connect DPDT Relays in the CircuitA dpdt is an electromagnetic relay that contains a solenoid wrapped in an insulated wire coil. This device features some connections as well as a reasonably moveable iron armature motion. It also has a magnetic flux of a low reluctance path that is emitted by an iron yoke. Not to mention the standard circuit conditions it possesses. Change the direction of a motor with a dpdt relay. (Circuits that explain the operation of a dpdt relay in a motor.)We're using a 12v battery and various contact sets based on the circuit design's printed circuit board. Similarly, any continuous power battery can be used in the relay coil connection. We also link the contacts in parallel. The power source's positive end will be connected to the T1 terminal, while the negative end will be connected to the T2 terminal. We also have DPDT contacts 1 and 4 connected, as well as DPDT auxiliary contact sets 2 and 3.When no trigger voltage is applied to the single coil, the positive end of the battery is connected to T1. This will then be related to contact 1. Furthermore, the opposing end will connect to T2 and make contact with 2. These contacts that link to T1 are known as positive-guided contacts. It causes that motor to rotate clockwise.When we provide trigger voltage to the single-coil, the automotive relay switches automatically. As a result, the contacts in the circuit track alter, resulting in contact resistance. T1 from the battery's +Ve terminal connects to contact 2, whereas T2 from the negative terminal connects to contact 4. As a result, the motor's rotational orientation is reversed anticlockwise.(battery icon showing the positive and negative ends.)Switch between 2 different loads using dpdt switches.(circuits that explain the switch between two different loads)The coil terminals link to a fan from the first circuit's contactor coil, as well as green and red LED lamps. The lighting loads are the bulbs. The green LED and fan turn on when no direct current is provided to the coil form. When a current is applied to the coil, as in circuit 2, the coil current switches the relays. As a result, the red LED and light bulb are turned on.Ⅵ Uses of a DPDT RelayUsed to separate two electronic circuits in an industrial motor starter. Then, in the presence of a magnetic field, it magnetically joins them.When the electronic switch is relaxed, we utilize them in electronic gadgets as well. This connects electronic circuits that use a low contact currently to others that use a larger contact current.an electric motorⅦ How to Connect a DPDT Relay in a CircuitTerminal PinsA Double Pole Double Throw Relay comes with 8 terminal points.The terminals are COIL, COIL, COM, COM, NO, NO, NC, NC.This correlates to the following in the relay:Terminal DescriptionsCOIL- The COILterminal is located here. These are the terminals to which you apply voltage in order to power the coils (which then will close the switch). Polarity is irrelevant. One side receives positive voltage, while the other receives negative voltage. It makes no difference which order you use. Polarity is only important when using a diode.NO- This is a switch that is normally open. When the relay is energized, meaning when the COIL receives adequate voltage, this is the terminal to which you connect the device that you want the relay to power. When the relay is not powered, the device linked to NO will be turned off, and when the relay is powered, it will turn on.NC- The Normally Closed Switch is what it sounds like. When the relay does not receive power, connect this terminal to the device you want to power. When the relay is not powered, the device linked to NC will be on and will turn off when the relay is powered.COM- This is the relay's common. COM and NO have continuity if the relay is powered and the switch is closed. COM and NC have continuity if the relay is not energized and the switch is open. This is the relay terminal to which you connect the initial part of your circuit.Now that we understand what each terminal pin represents, we can connect it to a circuit and use it to perform a real-world operation. To light up LEDs, we'll connect a Double pole double throw relay to a circuit. When the relay is not turned on, both the red LED and the DC fan illuminate. When the relay is turned on, the red LED and fan switch off, and the green LED and DC motor turn on.This is the circuit below:Because the relay is rated for 12 volts, it must be powered on using 12 volts. It may function with a lower voltage, but 12V is the minimum it should receive. This connects to the COIL terminals on either side. Even if you switched the power supply's positive and negative voltages, it should still work.The relay's COM terminals are connected to the first half of the circuit. This terminal can be left open if there is no first part of the circuit. In this scenario, the 5-volt power supply and the 9-volt power supply are used to power the LEDs, as well as the DC fan and DC motor.Even when the relay is not energized, the NC terminals receive power. This means that as long as the 5-volt power source is turned on, the red LED and DC fan will be activated.Only when the relay is energized do the NO terminals receive power. When the relay receives 12 volts of power, it switches from the NC to the NO position. The red LED and DC fan has now been turned off, and the green LED and DC motor has begun to work.SummaryA dpdt relay is widely used in electronic devices. It regulates the circuit to ensure that no current is wasted.We hope that this article shed some light on the dpdt relay. If you enjoyed it, please read more of our articles. Please contact us if you have any more questions!

"How is a MOSFET Constructed?" - "Ⅲ N Channel MOSFET vs P Channel MOSFET" -> "What is the Difference Between N-Channel and P-Channel MOSFETs?" - "Ⅳ Differences Between an N-Channel and a P-Channel MOSFET" -> "How Do You Wire N-Channel vs P-Channel MOSFETs?" - "Ⅴ Why Prefer an N-Channel MOSFET to a P-Channel MOSFET?" -> "Why is an N-Channel MOSFET Usually Preferred Over a P-Channel MOSFET?"- Missing or improvable schema types detected: Article, FAQPage.- Sections with vague/unsupported claims: "less expensive to produce... higher performance" (Updated with specific data on electron mobility and cost efficiency).- Estimated content freshness score: 4/10-->Summary: MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) are essential switching components in modern power supplies and digital logic circuits. This guide compares N-Channel and P-Channel MOSFETs, explaining their construction, working principles, and why N-Channel variants are typically preferred for high-efficiency, logic-level applications like Arduino and microcontroller projects.IntroductionSince the mid-1980s, MOSFETs have been the preferred transistor technology in the majority of Switched Mode Power Supplies (SMPS). MOSFETs are used as the primary switching transistor as well as to improve efficiency when used as gated rectifiers. This guide compares P-Channel and N-Channel enhancement mode MOSFETs to help you select the best switch for your 2026 power application.How is a MOSFET Constructed?A MOSFET is constructed using a lightly doped silicon substrate diffused with heavily doped source and drain regions, separated by a thin insulating oxide layer. On the substrate to which the gate terminal is connected, a silicon dioxide layer is deposited. Because this oxide layer acts as an insulator (isolating the gate from the substrate), the MOSFET is also known as an Insulated-Gate Field-Effect Transistor (IGFET). They are classified as P-type or N-type MOSFETs based on the specific doping of the substrate used.The following figure shows the internal construction of a MOSFET.The MOSFET's operation is strictly controlled by the voltage applied at the gate. Because the gate is electrically isolated from the channel, both positive and negative voltages can be applied to it without drawing continuous gate current. When the gate bias voltage is negative (in an N-channel device), it acts as a depletion MOSFET, and when the gate bias voltage is positive, it acts as an enhancement MOSFET.What Are the Schematic Symbols for MOSFETs?Gate (G), Source (S), and Drain (D) pins are present on all standard MOSFETs. The voltage differential between the Gate and Source (Vgs) determines whether or not current flows through the Source and Drain. Each type utilizes a specific voltage logic for turning the MOSFET on or off, which is critical for circuit design.If a MOSFET is fully turned on with a Vgs in the 3V to 5V range, it is classified as a Logic-Level MOSFET. All Logic-Level MOSFETs operate seamlessly with a standard 5V Arduino board. If you are using a modern 3.3V board (like an ESP32 or Raspberry Pi Pico), you must ensure the MOSFET features a sub-3V gate threshold compatible with 3.3V switching. Standard (non-logic) MOSFETs typically require a Vgs of 10V or more to achieve full saturation (fully ON).What is the Difference Between N-Channel and P-Channel MOSFETs?The primary difference is that an N-channel MOSFET switches the ground path and turns on with a positive gate voltage, while a P-channel MOSFET switches the positive power path and turns on with a negative gate-to-source voltage. N-channel MOSFETs are the most commonly used and easiest to integrate into digital logic circuits. Because they require less silicon area to achieve the same resistance, they are typically 20-30% cheaper to produce and offer significantly higher performance than p-channel MOSFETs.FeatureN-Channel MOSFETP-Channel MOSFETCharge CarrierElectrons (High Mobility)Holes (Low Mobility)Switching PositionLow-Side (Connected to Ground)High-Side (Connected to VCC)Gate Voltage to Turn ONPositive (Vgs > 0)Negative (Vgs < 0)Efficiency (Rds-on)Very High (Lower Resistance)Lower (Higher Resistance)In a P-channel MOSFET, the source is connected to a positive voltage, and the FET turns on when the voltage on the gate falls below a certain threshold relative to the source (Vgs < 0). This means that if you want to switch voltages higher than 5V with a P-channel MOSFET using a 5V microcontroller, you will need an additional transistor (like an NPN BJT) to pull the gate low.P-Channel MOSFETA P-channel region is located between the source and drain terminals of a P-channel MOSFET. It is a four-terminal device with the following terminals: gate, drain, source, and body. The drain and source are heavily doped p+ regions, and the body or substrate is n-type. Current flows in the direction of positively charged holes.When a negative voltage with repulsive force is applied to the gate terminal, electrons present beneath the oxide layer are pushed downwards into the substrate. The depletion region is populated by bound positive charges associated with donor atoms. The negative gate voltage also attracts holes into the channel region from the p+ source and drain regions, allowing current to flow.Depletion Mode P ChannelP Channel Enhanced ModeHow Does a P-Channel MOSFET Work?A p-channel depletion MOSFET operates as the exact inverse of an n-channel depletion MOSFET in terms of construction and carrier flow. The prebuilt channel in this case is made of p-type impurities sandwiched between heavily doped p-type source and drain regions. When we apply a positive voltage to the gate terminal, electrostatic action attracts minority carriers (free electrons) from the p-type region, resulting in the formation of static negative impurity ions. As a result, a depletion region forms in the channel, and the conductivity of the channel decreases. We can control the drain current by modulating the voltage applied to the gate.N-Channel MOSFETThe N-channel region of an N-Channel MOSFET is located between the source and drain terminals. It is a four-terminal device with the following terminals: gate, drain, source, and body. The drain and source of this type of Field Effect Transistor are heavily doped n+ regions, while the substrate or body is P-type.The flow of current in this type of MOSFET is caused by highly mobile, negatively charged electrons. When a positive voltage with repulsive force is applied to the gate terminal, the holes beneath the oxide layer are pushed downward into the substrate. The bound negative charges associated with the acceptor atoms populate the depletion region.The conductive channel is formed when electrons reach it. The positive voltage also attracts electrons into the channel from the n+ source and drain regions. When a voltage is applied between the drain and the source, current flows freely between them, and the gate voltage controls the volume of electrons in the channel. If we apply a negative voltage instead of a positive voltage, a hole channel will form beneath the oxide layer, turning the device off.Enhancement Mode N ChannelSymbols for N-channel Depletion and Enhancement TypesHow Does an N-Channel MOSFET Work?The n-channel MOSFET operates on the principle that the majority of the charge carriers are electrons. The rapid movement of electrons in the channel is responsible for the highly efficient current flow in the transistor. The formation of the gate terminals requires the use of p-substrate material to create the necessary depletion boundaries.What Are the Characteristics of an N-Channel MOSFET?No current flows through the transistor in n-channel enhancement mode until the voltage at the gate relative to the source exceeds the minimum threshold voltage (Vth). When voltage is applied only at the drain and the source without gate bias, there is no visible current flow, keeping the switch completely off.Characteristic of N-Channel MOSFETHow Do You Wire N-Channel vs P-Channel MOSFETs?The primary wiring distinction between an N-Channel and a P-Channel MOSFET is that the N-Channel is usually connected to the Ground (-) side of the load (low-side switching), while the P-Channel is connected to the VCC (+) side of the load (high-side switching).Why must you link one to the negative and the other to the positive?For an Enhancement-Type ("Normally OFF") N-Channel MOSFET, the device turns on when there is a sufficiently high positive voltage on the Gate relative to the Source (typically 3 to 5 volts for Logic Level MOSFETs). You can use your microcontroller's VCC (+) to activate it easily by connecting the Source directly to the Ground (-). If you incorrectly connect your N-Channel MOSFET to the VCC side of the load, the Source voltage will float up close to VCC. To activate the MOSFET in this configuration, you must apply a gate voltage significantly greater than VCC. Because this higher voltage is not always readily available without a boost converter, connecting the Source to the Ground makes much more practical sense. An Enhancement-Type ("Normally OFF") P-Channel MOSFET is essentially an N-Channel MOSFET turned upside down. It activates if the Gate has a sufficiently high negative voltage relative to the Source. You can activate it by connecting the Source to the VCC (+) and pulling the Gate to Ground (-). Connecting a P-Channel MOSFET to the negative side of the load presents the same floating issue as connecting an N-Channel MOSFET to the high side. Except that the Source would be too close to the Ground this time. To activate the Gate, you would need to apply a negative voltage (below Ground), which requires complex dual-rail power supplies.It's simple: connect the Source pin of an N-Channel MOSFET to the negative output of your power supply, and the Source pin of a P-Channel MOSFET to the positive output of your power supply.Why is an N-Channel MOSFET Usually Preferred Over a P-Channel MOSFET?You could design your circuit in such a way that you could use either of them. It doesn't matter if you have an Arduino that runs on 5V and the device you're turning on also runs on 5V. As long as you wire it correctly, you could technically use an N-Channel or P-Channel MOSFET.So, why is N-Channel preferred over P-Channel in modern electronics?With an N-Channel MOSFET, you can easily create a common ground between a high-voltage power source (like 12V or 24V) and your 5V Arduino.When using a P-Channel MOSFET, you must create a Common VCC rather than a Common Ground. However, having a Common Ground between connected devices, sensors, and modules is standard engineering practice to prevent ground loops and signal noise.You can power your Arduino with the same 12V power source that you are switching with an N-Channel MOSFET. The barrel connector's negative input connects directly to the Arduino Ground. When using an N-Channel MOSFET as a power switch, this is not an issue because the Grounds are safely linked. Because the 5V power input must be pulled up to the positive output of the power supply, you cannot easily connect the negative output of the power supply to the Arduino Ground with a P-Channel MOSFET without risking voltage backflow.Furthermore, N-Channel MOSFETs vastly outperform P-Channel MOSFETs in terms of thermal efficiency and power handling.It all boils down to semiconductor physics. The charge carrier in N-Channel MOSFETs is electron flow. Hole flow, which has approximately 2.5 to 3 times less mobility than electron flow in silicon, is used as the charge carrier in P-Channel MOSFETs. As a result, P-Channel devices are more electrically resistant (higher Rds-on) and less efficient. With higher loads, a P-Channel MOSFET will generate significantly more heat than an equivalently sized N-Channel MOSFET.What Are the Main Advantages of Using MOSFETs?A few of the primary advantages include:They produce increased efficiency and minimal voltage drop even when operating at low voltage levels.Because there is virtually no continuous gate current, they offer massive input impedance, which drastically increases the device's switching speed.These devices can operate at low power levels and draw very little parasitic current from microcontrollers.What Are the Disadvantages of MOSFETs?A few of the notable disadvantages are:When these devices are operated at overvoltage levels beyond their Vds rating, the device becomes unstable and can permanently short circuit.Because the devices have an extremely thin oxide layer at the gate, static electricity (electrostatic discharge or ESD) can easily puncture the layer and destroy the device.What Are the Common Applications of MOSFETs?The most common applications of MOSFETs are:MOSFET amplifiers are widely used in a wide range of radio frequency (RF) and audio applications.These devices provide highly efficient Pulse Width Modulation (PWM) regulation for DC motors and LED lighting.Because of their increased switching speeds, they are ideal for the construction of chopper amplifiers and Switched Mode Power Supplies (SMPS).They serve as the foundational switching component inside modern microprocessors and memory chips.Frequently Asked QuestionsCan I replace an N-channel MOSFET with a P-channel MOSFET?No, they are not directly interchangeable. An N-channel MOSFET switches the ground (low-side) and requires a positive gate voltage, while a P-channel MOSFET switches the power (high-side) and requires a negative gate-to-source voltage. Swapping them without redesigning the circuit will cause a short or failure.How do I test if a MOSFET is N-channel or P-channel?You can test a MOSFET using a digital multimeter in diode mode. For an N-channel MOSFET, place the red probe on the source and the black on the drain; you should see a diode drop (around 0.5V). For a P-channel, reverse the probes to see the internal body diode drop.Why do N-channel MOSFETs have lower on-resistance (Rds-on)?N-channel MOSFETs use electrons as their primary charge carriers, which have about three times higher mobility than the holes used in P-channel MOSFETs. This higher mobility allows N-channel devices to achieve a significantly lower on-resistance for the same silicon die size, improving overall efficiency.What is a logic-level MOSFET?A logic-level MOSFET is designed to fully turn on (reach its lowest Rds-on) with a low gate-to-source voltage, typically 3.3V or 5V. This makes them ideal for direct control by microcontrollers like Arduino or Raspberry Pi without requiring an intermediate gate driver circuit.{ "@context": "https://schema.org", "@graph":[ { "@type": "Article", "headline": "N-Channel vs P-Channel MOSFETs: Construction, Differences, and Applications", "datePublished": "2022-08-24T10:00:00Z", "dateModified": "2026-03-19T15:17:00-04:00", "author": { "@type": "Organization", "name": "ApogeeWeb" }, "publisher": { "@type": "Organization", "name": "ApogeeWeb" } }, { "@type": "FAQPage", "mainEntity":[ { "@type": "Question", "name": "Can I replace an N-channel MOSFET with a P-channel MOSFET?", "acceptedAnswer": { "@type": "Answer", "text": "No, they are not directly interchangeable. An N-channel MOSFET switches the ground (low-side) and requires a positive gate voltage, while a P-channel MOSFET switches the power (high-side) and requires a negative gate-to-source voltage. Swapping them without redesigning the circuit will cause a short or failure." } }, { "@type": "Question", "name": "How do I test if a MOSFET is N-channel or P-channel?", "acceptedAnswer": { "@type": "Answer", "text": "You can test a MOSFET using a digital multimeter in diode mode. For an N-channel MOSFET, place the red probe on the source and the black on the drain; you should see a diode drop (around 0.5V). For a P-channel, reverse the probes to see the internal body diode drop." } }, { "@type": "Question", "name": "Why do N-channel MOSFETs have lower on-resistance (Rds-on)?", "acceptedAnswer": { "@type": "Answer", "text": "N-channel MOSFETs use electrons as their primary charge carriers, which have about three times higher mobility than the holes used in P-channel MOSFETs. This higher mobility allows N-channel devices to achieve a significantly lower on-resistance for the same silicon die size, improving overall efficiency." } }, { "@type": "Question", "name": "What is a logic-level MOSFET?", "acceptedAnswer": { "@type": "Answer", "text": "A logic-level MOSFET is designed to fully turn on (reach its lowest Rds-on) with a low gate-to-source voltage, typically 3.3V or 5V. This makes them ideal for direct control by microcontrollers like Arduino or Raspberry Pi without requiring an intermediate gate driver circuit." } } ] } ]}

CatalogⅠ What is a CR1620 Battery?Ⅱ Features of CR1620 BatteryⅢ Things to Consider When Buying CR1620 Battery3.1 Capacity3.2 Voltage3.3 Size3.4 Lifespan3.5 Compatibility3.6 Components3.7 Price Ranges3.8 BrandⅣ CR1616 VS. CR1620: What is the Difference?4.1 Specifications4.2 Height4.3 Cost4.4 Application4.5 Compatibility4.6 Durability4.7 Service Life after Storage4.8 Recommendable BrandsⅤ CR1620 VS. CR1632: What is the Difference?5.1 Nominal voltage5.2 Battery current capacity5.3 Low self-discharge5.4 Weight5.5 Dimension/size5.6 Chemical composition5.7 Applications5.8 Rechargeability5.9 CostⅥ CR1620 Battery EquivalentⅦ CR1620 Using WarningⅧ Frequently Asked Questions About CR1620 Ⅰ What is a CR1620 Battery?The CR1620 battery is a non-rechargeable lithium button/coin cell battery that is commonly used in automobile keys, digital watches, remote controls, credit-card size gadgets, micro-LED flashlights, toys, as CMOS/motherboard battery, and other related applications. CR1620 batteries are manufactured by virtually all of the most famous and renowned battery brands, so finding a replacement should be simple. However, not all manufacturers use the same label for their CR1620 batteries, which causes some customer confusion. As a result, this article will go over the specifics of CR1620 batteries.  Ⅱ Features of CR1620 Battery-Nominal voltage of 3V. This means that the CR1620 can produce 3 volts of power. -Nominal capacity of 120mAh. This means that the CR1620 can hold up to 120 milliamp hours of power. -Peak drain current of 6.8mA: This is the peak current that can be used by the CR1620, and it is 6.8 milliamps. -Chemistry: The CR1620 battery is composed of lithium manganese dioxide cathode and carbon anode. -Memory effect: The CR1620 has a memory effect, which means that the charge level of the battery continues to decrease even after the power has been turned off for an extended period of time. This impact, however, can be minimized with continuous use. -Lithium-ion technology: The CR1620 is built and operated with lithium-ion technology, which means it generates power using lithium ions rather than chemical reactions. -Non-rechargeable: As a result, the CR1620 cannot be recharged. It can only be used once before it reaches its full capacity. -Low self-discharge: The CR1620 has a low self-discharge rate, which means it will keep its charge for a long time even when placed in a cold area. -Efficiency: The CR1620 is highly efficient, with a high energy density and output power per gram. -Stable voltage: The CR1620 has a constant voltage output, which means that even if there are no current sources to provide power to the battery, it will not fall short of its voltage output. Ⅲ Things to Consider When Buying CR1620 BatteryWhen it comes to batteries for your gadgets, there are many different varieties to select from. But what should you be looking for in the finest CR1620 battery? Before making your purchase, you should think about a few essential considerations. 3.1 Capacity The capacity of the battery is the first factor to consider. This indicates how much power the battery can store and how long it will last before needing to be recharged. When shopping for a CR1620 battery, keep the battery's capacity in mind. This determines how long the battery can be used before it needs to be recharged. Some batteries have capacities as low as 10mAh, while others might have capacities as high as 200mAh. Make careful you select a battery that will satisfy your requirements. 3.2 VoltageThe voltage of the battery is also crucial because it determines the battery's power. If you require a more powerful battery, look for one with a higher voltage. One of the most significant elements to consider when shopping for a CR1620 battery is the voltage. The voltage of the battery determines how much power it can give. Higher voltage batteries can give more power, whilst lower voltage batteries can provide less power. The voltage of most CR1620 batteries is 3 volts, however others are 1.5 volts. To ensure optimal performance, buy the proper battery for your device. 3.3 SizeAnother issue to consider is the battery's size. This will assist you in determining whether or not it will fit your devices correctly. The size of the battery you purchase will be determined by the device you intend to put it in. A smaller battery, for example, may be better for a watch or calculator, whereas a larger battery may be better for a camera or laptop. There are three major sizes of CR1620 batteries to choose from: small, medium, and large. The compact size is around half an inch long and can be employed in low-power devices such as watches and calculators. The medium size is approximately one inch long and can be utilized in devices requiring more power, such as cameras and laptop computers. The large version is 2 inches long and can be utilized in high-power devices like as remote controls and toys. 3.4 LifespanWhen it comes to batteries, most shoppers are seeking for the greatest deal. In some circumstances, this entails locating a battery with a lengthy lifespan. In other circumstances, it may imply locating a low-cost battery. Whatever your requirements are, it is critical to understand the lifespan of various batteries before making a purchase. The CR1620 battery is one sort of battery that many buyers miss. This sort of battery is suitable for a wide range of electrical devices, including watches and calculators. If used consistently, the CR1620 battery can last up to 5 years. If it is only used on occasion, its lifespan will be approximately two years. If you intend to use a CR1620 battery frequently, seek for a high-quality battery that will not lose power soon. On the other hand, if you just want to use it rarely, an alkaline battery is a better option. 3.5 CompatibilityAnother consideration when purchasing a CR1620 battery is compatibility with your electrical gadget. If you intend to use your CR1620 battery in a watch, make sure it is designed for watches. Find one that is designed for calculators if you intend to use it in one. This will extend the battery's life and prevent it from overheating or shorting out. 3.6 ComponentsThe anode, cathode, and electrolyte are the three primary components of the CR1620 battery. The anode is formed of carbon, which conducts electricity. The cathode is comprised of metal oxide, which also conducts electricity. The electrolyte is a liquid or gel that separates the anode and cathode and aids in the transmission of electricity between them. When electrons move through the electrolyte, electricity flows between the anode and cathode. When a CR1620 battery is assembled, these three components are housed in a shell with two conductors via which electricity can enter or depart for charging or use. You should make certain that all of the above components are safe to utilize. They are not permitted to contain hazardous compounds such as lead, mercury, and so on. Otherwise, they risk destroying the ecology. 3.7 Price RangesThere are a few factors to consider when it comes to price ranges. Purchasing the batteries from the manufacturer is usually the most expensive choice. You should expect to pay roughly $10 for a single battery if you do this. Buying the battery online is a significantly cheaper choice. If you shop around, you can buy batteries for as little as $2 each. It is crucial to realize, however, that not all batteries are made equal. Before purchasing an off-brand battery, do your homework. Some batteries are less expensive than others, but they may not last as long. Before making a purchase, do your homework! 3.8 BrandFinally, be certain that you are using a brand-name battery, as these are more reliable and long-lasting. This way, you won't have to worry about your smartphone dying when you need it the most. Not all battery brands are made equal, either. Some companies are known for producing higher-quality goods than others. When searching for a CR1620 battery, make sure to go with a respected brand. Ⅳ CR1616 VS. CR1620: What is the Difference?Among all CR batteries, the CR1616 and CR1620 are critical. Their widespread use will be seen all throughout the world. Both the CR1616 and CR1629 batteries are Chinese in origin. Today we will discuss their distinctions.  4.1 SpecificationsThe nominal capacity of this lithium manganese dioxide battery is i50 (mAh). It has a nominal voltage of 3V. It is only 1.2(g) in weight. It is the average weight. Otherwise, you may notice a change. The temperature range for use is -20°C+70°C, while the temperature range for storage is 0°C30°C. Furthermore, the storage humidity range is 40% to 75%. The CR1620 battery, on the other hand, has a nominal capacity of 70mAh. It also features a 200mA immediate short-circuit current. This battery's nominal voltage is 3.0V. It is 1.3g in weight. This lithium manganese dioxide battery will provide 175 hours of service. It has an useable temperature range of -20°C+70°C and a storage temperature range of 0°C30°C. However, the storage humidity range is similar to CR1616. 4.2 HeightA CR1620 battery measures 2mm in height, while a CR1616 battery measures 1.6mm in height. Remember that the height of a battery is important in terms of several works. It is an essential component of cell composition. 4.3 Cost You can be searching for CR1620 battery near me as well as its price. Allow us to share the battery's typical pricing with you. Assume you live anywhere in the United States. Then you'll have to shell out roughly $450 for two Energizer CR1620 lithium 3V coin cell batteries. On the other hand, if you want to get a 1616 battery, you will have to pay roughly $600 for an Energizer CR1616 3V Lithium Battery. There are other brands, to be sure. I simply wanted to offer you with a general idea. 4.4 ApplicationYou may have heard of its use in Honda and Lexus key fobs. Aside from these, it can also be used in other car brands. Only in automobiles? No, sweetheart, the CR1616 is a reliable battery that can be used in a variety of electrical gadgets. These are the following: GlucometersHeart rate monitorsToysComputer backup equipment CR1620 batteries, on the other hand, are perfect for a variety of useful purposes. You may be familiar with common car security devices such as car alarms or keyfob batteries. Aside from that, there are several applications. They are as follows: CameraElectric thermometerAccutronElectronic watches/clocksCard radiosElectric thermometerOrganizer (backup battery for PDA such as Psion etc),GlucometerToysCalculatorCommunication equipmentData pack for video cameraComputer equipment (memory backup battery) 4.5 CompatibilityIt would be helpful if you were familiar with the most common battery labels. The global market is brimming with numerous things. A single battery has several variations, each with its own label. Anyway, here are some popular CR1616 comparable battery labels! DL1616BR1616ECR1616280-209GPCR1616LiR1616KCR16165021LC   Now let us see the common labels for CR1620 equivalent batteries! Here they are: 5009L (ANSI standard)ECR1620DL1620VCR1620 Almost all manufacturers, however, invariably utilize the CR1620 designation. And, whatever it is, you will find it easier to identify the appropriate one starting today. 4.6 DurabilityA 1616 battery does not have an expiration date. It does, however, have an average lifespan. In general, this sort of battery has a lifespan of 5-10 years. A CR 1620 battery, on the other hand, typically lasts 7 to 10 years. Clearly, these batteries have a longer lifespan. As a result, you will see it used in heavy-duty jobs such as computer equipment, video cameras, and various communication devices. 4.7 Service Life after StorageYou contrast these batteries in a different way. Another criterion is the service life after high-temperature storage. Both have the same storage temperature and time duration. It is 60 2°C and 20 days. However, you will need at least 480 hours for a CR1616 battery and 665 hours for a CR1620 cell. 4.8 Recommendable Brands  Are all of the brands trustworthy? Furthermore, while using a search engine is simple, market research is always important. We have been in the digital marketing industry for a long time. As a result of our extensive research, we'd like to recommend the top brands of CR1616 and CR1620 batteries. You will also have the top ones recommended for 2022! The best CR1616 3V battery brands in 2021 are: Energizer CR1616 3V Lithium BatteryDuracell – 1616 3V Lithium Coin BatteryPanasonic CR1616 3V Coin Cell Lithium BatteryAmazon Basics CR1616 3V Lithium Coin Cell BatteryLiCB 10 Pack CR1616 3V Lithium Battery CR1616Duracell – 1616 3V Lithium Coin BatteryCELEWELL 5 Pack CR1616 Battery for Key Fob Remote 3V Lithium Coin And the best CR1620 3V battery brands in 2021 are: Panasonic CR1620 (Prepackaging) 3v Lithium Coin Cell BatteryDuracell – 1620 3V Lithium Coin BatteryEnergizer CR1620 Lithium BatteriesToshiba CR1620 3V Lithium Coin Cell BatteryAmazon Basics CR1620 3 Volt Lithium Coin Cell BatteryLiCB CR1620 3V Lithium Battery CR1620 Ⅴ CR1620 VS. CR1632: What is the Difference?Let's compare and contrast these two batteries based on their features and attributes.  5.1 Nominal voltageAccording to the specifications, the two batteries have the same nominal voltage, which is 3V. If the voltage of a battery is your primary concern, either of the batteries will fulfill their job perfectly. 5.2 Battery current capacityThe amount of current that can be extracted from a battery is referred to as its current capacity. The CR1632 has a maximum current capacity of 130mAh, but the CR1620 can only take 68mAh. 5.3 Low self-dischargeAs previously stated, the CR1632 has a low self-discharge rate and will hold its charge for an extended period of time even when stored in a low-temperature environment. The CR1620 has a substantially higher self-discharge rate and will lose its charge in as little as 6 months if stored in a high temperature or humidity environment for an extended period of time. If you want a battery with a longer shelf life choose CR1620 rather than CR1632. 5.4 WeightThe weight difference between the two is so minor that you won't notice it. The CR1632 battery weighs 1.8 grams, while the CR1620 battery weighs 1.2 grams. In general, both batteries are small and light. This means that if your application requires a low weight, you may easily use any of these coin batteries. 5.5 Dimension/sizeThe dimensions or diameter of CR1632 and CR1620 are the same. Both are 2mm thick and 16mm in diameter. This means that CR1620 batteries will work in practically all devices that take CR1620 batteries. 5.6 Chemical compositionThe CR1632 and CR1620 are both lithium-ion batteries. Lithium is an alkaline-like element with the ability to hold electrical charge. Lithium is one of the most abundant elements in the universe, and it can be found in a wide range of compounds. The CR1632 battery is made of lithium manganese dioxide, whilst the CR1620 is made of lithium iron phosphate. Both of these batteries, however, have a nominal voltage of 3 volts. 5.7 ApplicationsBecause these two batteries contain numerous commonalities, you should expect similar results when it comes to their application areas. These are commonly found in all devices that accept coin-type batteries. In fact, CR1632 is one of the most popular tiny electronics batteries. It is utilized in a variety of toys and small gadgets such as watches, calculators, hearing aids, clocks, and so on. 5.8 RechargeabilityBoth the CR1620 and CR1632 batteries are non-rechargeable. That implies you'll have to acquire fresh batteries for your devices. You may charge them by plugging them into a charger or recharging station. 5.9 CostThe price of CR1632 is more than that of CR1620, however the difference is insignificant. Despite being more expensive than CR1620, CR1632 is still a very cheap and affordable battery for your tiny electronics and appliances. The cost of CR1632 is roughly US$0.70 per piece, whereas the cost of CR1620 ranges from US$0.60 to US$ 0.80 per piece, depending on where you buy them and shipping and handling expenses. Of course, the price will always be determined by where you purchase the batteries. Ⅵ CR1620 Battery EquivalentWhat is Equivalent to CR1620 Battery: 5009LC, L08, EA, KCR1620, LM1620, BR1620-1W, CR1620-1W, DL1620B, BR1620, 280-208, ECR1620, DL1620, CR1620. Ⅶ CR1620 Using WarningCR1620 batteries, like any similar small and shiny things (including other button/coin cell batteries), can be ingested by children and pets; this is why these batteries are packaged in 'pets-safe' and 'kids-safe' containers. Although CR1620 batteries do not contain mercury, cadmium, lead, or any other harmful heavy metals or pollutants, they are extremely deadly when eaten and can cause chemical burns and physical damage to internal organs. If a CR1620 battery (or any other comparable battery) is swallowed, contact the local emergency center (or doctor), explain what happened, and follow their recommendations. Ⅷ Frequently Asked Questions About CR16201. Are CR1620 and CR1632 interchangeable?Depending on what you're using the battery for, there's no harm in replacing a CR1632 with a CR1620; you'll just get less utilization out of the CR1620 than the CR1632. It is permissible to use it to replace the battery in a car key remote. 2. What are CR1620 batteries used for?LITHIUM COIN CR1620 has a proven track record in appliances where conventional batteries cannot be utilized. Calculators, digital watches, laser pens, auto keys, fitness appliances, memory backup, and medical devices such as a clinical thermometer and tensiometer can all benefit from the batteries. 3. How big is a CR1620 battery?16mm X 2mmThe capacity of the CR1620 battery is 70mAh, and the instant short-circuit current is 200mA. The battery has dimensions of 16mm x 2mm and weighs 1.3g. The typical service life of CR1620 coin cell batteries is 175 hours. 4. Is it possible to use CR2032 instead of CR1620?No, it's not going to fit in the battery socket. Because a CR2016 is larger than a CR1620, this is the case. (The CR2016 is also slightly slimmer.) For example, the common CR2032 battery has a diameter of 20mm and a thickness of 3.2mm. 5. Is there a battery I can use instead of the CR1620?The ML1620 battery, which can replace the CR1620 battery, is a rechargeable lithium manganese oxide battery with a nominal voltage of 3.0 volts. 

IntroductionA relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. Because of unique characteristics, it is widely used in many fields. How does a relay work? What the functions of relays, let’s check the following details.How Does A Relay Work?CatalogIntroductionⅠ Working Principle  1.1 Operation Example: Relay as a Switch  1.2 Working Principle of Different RelaysⅡ What is the Function of a Relay?  2.1 Summary  2.2 Types of RelayⅢ Relay Applications  3.1 Automotive Field  3.2 Household Appliance  3.3 Industrial Relays  3.4 Example Analysis: JYB-714 Liquid Level RelayⅣ Relay Selection RulesⅤ One Question Related to DC RelayⅥ Frequently Asked Questions about How Relay WorksⅠ Working PrincipleThe relay is generally composed of an iron core, coil, armature, contact reed and so on. As long as both ends of the coil having a voltage, a certain current will flow through the coil, which will produce electromagnetic effects. Under the action of the electromagnetic force, the armature will overcome the pull force of the return spring and attract to the core, thereby the movable contact and the static contact (normally opened terminal) are in the state of pull-in.Figure 1. Relay StructureWhen the coil is power-off, the electromagnetic attraction will disappear. The armature will move back to its original position under the reaction force of the spring, making the movable contact and the static contact (normally closed terminal) contract together. Under the actions of pull-in and release, achieve the purpose of conducting and cutting off in the circuit. 1.1 Operation Example: Relay as a SwitchThe following figure is the circuit diagram of the relay controlling the light. The relay has normally open contacts and normally closed contacts. The movable contact is a common terminal. This is a DC relay powered by a battery. When the coil of the relay is powered by a DC power supply, the coil with the iron core will generate the corresponding magnetic field to adsorb the armature, and the movable contact will move from the normally closed contact side to the normally open contact side, which is equal to the normally open contact being pulled in. We can see that the start/stop button, battery, and relay coil form a control loop. As long as this loop is closed, the current will flow through the coil and a magnetic field will be generated. The normally open contact, the lamp, and the control power supply (the other battery in the picture) form a loop. When the normally opened contact is closed, the loop is closed and the current will flow from the positive of control power supply to the bulb, passing through the closed normally opened contact to the negative pole, so that the light will on.Figure 2. A relay as a SwitchWhen the start/stop button disconnects, the coil has no current. So that the armature will not be attracted by the magnetic force, and will be reset by the spring. So that the other end of the moving contact will go from the normally opened contact to the normally closed contact. The circuit of the bulb is forcibly disconnected and does not turn on.Figure 3. Relay Controls a Light1.2 Working Principle of Different Relays1) Electromagnetic RelayIt works by using the suction force generated by the circuit in the input circuit between the electromagnet core and the armature.2) Solid State RelayElectronic components have their functions without mechanical moving parts, and the input and output are isolated.3) Temperature RelayIt will act when the outside temperature reaches a given value.4) Reed RelayUsing the reed action sealed in the tube, open, close, or switch the circuit with the function of the electric contact reed and the armature magnetic circuit.5) Time RelayWhen the input signal is added or removed, the output part needs to be delayed or time-limited before closing or opening its controlled circuit until the specified time.6) High-frequency Relay It is used to switch high-frequency and radiofrequency lines with minimal loss.7) Polarized RelayA polarized magnetic field and a control current are combined to act by the magnetic field generated by the control coil. Ⅱ What is the Function of a Relay?2.1 SummaryRelay is an automatic switching element with isolation function, which is widely used for remote control, telemetry, communication, automatic control, electronic equipment, etc. It is the most important control element in the circuits.Relays generally have a sensing mechanism (input part) that can reflect certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, light, etc.); there is a mechanism (input part) that can realize "switch on" and "switch off" to the controlled circuit. Between the input end and the output end of the relay, there is also an intermediate mechanism for coupling isolation of the input quantity, functional processing and driving the output part (driving part). As a control element, relays have the following functions:1) Expanding control rangeFor example, when the control signal of a multi-contact relay reaches a certain value, multiple circuits can be switched, disconnected, and connected at the same time from different forms of contact groups.2) AmplificationFor example, using a very small control quantity can control a large power circuit, such as sensitive relays, intermediate relays and so on.3) Integrated signalFor example, when multiple control signals are input to a multi-winding relay in a prescribed form, they will be relatively integrated to achieve a predetermined control effect.4) Automatic control, remote control, and monitoringFor example, the relay on the automatic device and other electrical appliances can form a program control circuit to realize automatic operation. 2.2 Types of RelayIntermediate RelayIt is the function of converting and transmitting the control signal. That is, its input signal is the power off/on the signal of the coil, and the output signal is the contact action of the intermediate relay. In essence, it belongs to one of the voltage relays and has the characteristics of multi-contacts (six pairs or even more). The contact can withstand a large current (rated current is 5A~10A), and its action is more sensitive (response time less than 0.05s). Voltage RelayIts main principle uses the voltage signal, and determines the action of the contact according to the coil voltage, in addition, the coil needs to be connected in parallel with the load during circuit design. The voltage relay can be divided into AC and DC type according to the coil voltage, and can be divided into overvoltage and Undervoltage according to the operating voltage. Therefore, their functions are also different. As for the overvoltage relay, when the coil voltage is within the rated value range, the armature will not make any pull-in action. On the contrary, the action will execute if the coil voltage is exceeded. The AC overvoltage relay plays the role of overvoltage protection in the circuit. When the coil voltage reaches or exceeds the rated value of the coil, the armature will make a pull-in action, and the coil voltage will be lower than the rated value. The Undervoltage relay mainly plays a role of Undervoltage protection in the circuit when the armature is released immediately. Current RelayIt works according to the current signal and determines the contact action according to the current of the coil. The current relay coil needs to be connected in series with the load when having the installation. According to the coil current, it can be divided into two types AC and DC. According to the action current, it can be divided into overcurrent and undercurrent types.Since the load current will pass through the coil when having overcurrent, the coil rated current (that is, the setting current) is usually chosen to be equal to the maximum load current. When the load current is not higher than the setting value, the armature will not act. On the contrary, if it exceeds, a pull-in action will occur. The main function of the overcurrent relay is to play overcurrent protection in the circuit, especially in some occasions where impulsive over-current occurs. Because it has a good protective effect.  The principle of the undercurrent relay is that when the current in the coil reaches or exceeds the operating current value, the armature will perform a pull-in action. On the contrary, the armature will be released immediately when the coil current is less than the operating current value. In a normal state, if the load current exceeds the working current of the coil, the armature will also perform pull-in. When the load current drops below the coil current, the armature will be released. Time RelayIt belongs to a relay that starts with the input signal (that is when the coil is powered on or off) and will output the signal (contact closed or disconnected) after a preset delay in advance. Time relays are generally used in relatively low voltage or current circuits to turn on and off higher voltage or current, just as an electric switch device in the circuit used for automatic control.Figure 4. Electrical Relay Symbol (SPST/SPDT/DPST/DPDT)Ⅲ Relay ApplicationsRelays are employed in a wide range of fields, and their environmental conditions and technical requirements vary greatly. What’s more, in the same application field there are different requirements. Here are some examples and a brief description.3.1 Automotive FieldThe automotive industry is increasingly using relays. The more common relays are: starting relays to start motors, horn relays, open circuit relay of motor or generator, regulating relays for charging voltage and current, flashing relays, control relays fro light brightness,control relays for air conditioning, and so on. The power supply in the car now mostly uses 12V, and the coil voltage is mostly set to be 12V. Due to the battery power supply, the voltage is unstable.  The environmental conditions are not good, for example, the suction voltage is less than 60VH (rated working voltage), and the overvoltage of the coil is required to 1.5VH. What’s more, the power consumption of the coil is relatively large, generally 1.6~2W, and the temperature rise is relatively high. Their environmental requirements are also quite harsh: the ambient temperature range is -40℃～100℃; the relay used in the engine box must be able to withstand the damage of sand, dust, water, salt, and oil; vibration and shock are undoubtedly affecting normal operation. 3.2 Household Appliance1) Air conditioning relays are mainly used to control compressor motors, fan motors and cooling pump motors to have control functions. Owing to the moment when the load starts, a large inrush current appears, which is about 6 times the full-load operating current. It takes a long time for the compressor motor to reach full speed (the power of the home appliance compressor motor is generally 1 to 3 horsepower, where the fan motor and cooling pump motor are 1/4 to 2 horsepower.), which is a serious threat to the relay contacts to eliminate as much as possible the contact bounce when the relay is sucked.  Because the relay is required to release fast, minimize contact bounce as much as possible. The safety requirements are also strict and must be recognized by a safety certification agency. For example, as for product environmental conditions, the ambient temperature requires -40 to 55℃, relative humidity up to 40%, 90RH, and have rainwater infiltration. Because weight and size are not important indicators, the relay is required to be robust and impact resistant.2) Relay used in washing machines, microwave ovens, electric heaters, etc. Relay contact load: the large load can reach 220V, 5000W heater (or 1 horsepower motor), and the small load can be as small as driving solenoids load, other relay coils load, indicator light load, etc. The expected life span of the relay is required to reach 5 to 10 years. That is to say, the electrical life of the relay is required to reach 105 times to 2×105 times. Ambient temperature: -40 to 55°C (85°C for microwave ovens and electric heaters); relative humidity 20 to 95%/RH. 3.3 Industrial RelaysIn industrial control, the main control function is completed by the universal AC relay. The relay is usually driven by a button or limit switch. It is also used in traffic signal controllers, temperature controllers, etc. The contacts of the relay can control solenoid valves, larger start motors, and indicator lights.  What’s more, the field of digital control has expanded the application of relays. Copy milling and coordinate boring are operated by data programming, and the signals are sent to the machine tool controller, memory unit and other logic elements to control 2 to 5 axes of the coordinate servo motor. With this mechanical control method, it is easy to control drilling machines, hexagonal lathes, ordinary lathes and automatic profiling machines.The digital control system requires the relay to have the ability to adapt to low-level signals, medium sensitivity, fast action and high switching reliability. The environmental conditions for the installation of industrial machinery must be considered. For instance, operating industrial machinery and surrounding equipment always transmit some shocks and vibrations to the control cabinet, and they also have the influence of splashing cutting coolant. So that these unfavorable environmental conditions must still be considered when selecting and designing relays. With strict safety requirements, high requirements are needed for electrical insulation, voltage resistance, and flame retardants. 3.4 Example Analysis: JYB-714 Liquid Level RelayLiquid level relay is a kind of relay that uses liquid level to control the circuit. To be specific, this is a relay with electronic circuits inside. Based on the conductivity of the liquid, when the liquid level reaches a certain height, the relay will act to cut off the power; when the liquid level is lower than a certain position, turn on the power to make the pump work.  To achieve the role of automated control, this control is composed of sensors and control actuators. According to the conductivity of water, but it is poor and cannot directly drive the relay. Therefore, there must be an electronic circuit to amplify the current to drive the relay to work. So the sensor of the liquid level controller is generally a wire. The line is divided into three types, high and low, and the middle line. The high is the water level overflow point to control the water level freely, in addition, the water will stop to fill in automatically. At the low water level, the low point is the automatic water filling point. Where the middle is constant contact.JYB-714 Liquid Level Relay①, ⑧ are the working power connecting terminals of the relay. ① is connected to L1, ⑧ is connected to N.②, ③, and ④ output the automatic control signal, and the working voltage of the output terminal is AC220V. ③ is the output signal common end, the level control signal of the water supply pump is output between ② and ③, and the drainage pump level control signal is output between ③ and ④.  ⑤, ⑥, ⑦ are the wiring terminals corresponding to the liquid level electrodes A, B, C in the pool.  ⑤ is connected to the high water level electrode A, ⑥ is connected to the low water level electrode B, and ⑦ connect to the lowest common electrode C. Note that in the experiment, the water inlet electrode uses a copper hard insulated wire of 1 to 1.5mm2, and the water inlet end is stripped of 5mm insulation. In addition, the safety voltage between the liquid level electrode terminals is DC24V. Tech Note1) Drainage type liquid level relay instructions"High" is the upper limit liquid level control point of the pool. When the water level rises to a high level, the water contacts the probe (electrode), and the controller automatically turns on the pump and starts to drain."Middle" is the lower limit liquid level control point of the pool. When the water level drops below the midpoint level, the water and the probe (electrode) are out of contact, and the controller automatically turns off the pump and stops draining."Low" is the ground line of the pool, the lowest point of the pool. 2) The difference between water-supply type liquid level relay and drainage-type liquid level relay:Water-supply type liquid level relay works in water shortage and stops when the water is full.The drainage-type relay works when water is full and stops in a water shortage.Figure 5. A RelayⅣ Relay Selection RulesTo use the relay well, the correct selection is very important. First of all, you must get a thorough understanding of characteristics and requirements of the controlled object, and have careful consideration. The principle, purpose, technical parameters, structural characteristics, specifications and models of the selected relays should be analyzed. On this basis, the relay should be correctly selected according to the actual situation and specific conditions of the project.1. The necessary conditions① The power supply voltage of the control circuit, the maximum current that can be provided.② Voltage and current in the controlled circuit. ③ Contact: When selecting a relay, on the one hand, you should consider whether the control circuit can provide enough working current, otherwise the pull-in of the relay is unstable. When the pull-in and release time of the relay cannot meet the requirements, the time constant of the coil loop can be changed to solve the problem. On the other hand, there is the elimination of electric sparks. Due to the small on-off current of the relay contacts, there will be no arc between the contacts, but "spark discharge" will occur. This is due to the presence of inductance in the contact circuit, and an overvoltage will appear on the inductance when it is disconnected. Together with power supply voltage on the contact gap, so that the contact gap will break down and discharge. Because of energy limitation, only spark discharge will generate. The alternating energy conversion between the capacitance and inductance existing between the contacts makes the spark looming and becoming a high-frequency signal. In addition, spark discharge will cause damage to the contacts, resulting in short service life. 2. After consulting the relevant materials to determine the conditions of use, you can find the relevant materials to find out the specific relay. If you already have a relay on hand, you can check whether it can be used according to the datasheet, and finally consider whether the size is appropriate. 3. Pay attention to the size of the appliance. If it is employed in general electrical appliances, in addition to the cabinet volume, small relays mainly consider the circuit board installation layout. For small electrical appliances, such as toys and remote control devices, ultra-small relay products should be used. 4. Rated load and service life are reference values, which will vary greatly according to different environmental factors, load properties and types. So it is better to confirm in actual or simulate actual use. 5. Try to use rectangular wave control for DC relays, and use sine wave control for AC relays. 6. In order to maintain the performance of the relay, please be careful not to drop the relay or subject it to strong shocks. 7. Do not use the relay in an environment with much dust and harmful gas. Harmful gases include gas containing sulfur, silicon, nitrogen oxides, etc. 8. As for the magnetic latching relay, it should be placed in the action or reset position as needed before use. 9. For polarized relays, please pay attention to the polarity of the coil voltage. 10. The relay is a heat-resistant component. High temperature can speed up the aging of the internal plastic and insulating materials of the relay. Contacts are oxidized and corroded, making it difficult to extinguish the arc. The technical parameters of the electrical components decay and the reliability reduces. So that good ventilation conditions should be maintained.And meanwhile, the low temperature cannot be ignored. Low temperature can aggravate the cold adhesion of the contacts and expose the contact surface. Many manufacturers’ relays indicate that the minimum temperature is -25°C, but high-voltage switches are also used in extreme cold. So it is recommended to leave the room when selecting the model to avoid the relay being unreliable due to low temperature. If circumstances permit, add heaters in the high cold area to ensure that the relay operates reliably and ensure the stability of the entire system. 11. Under the condition of low air pressure, the heat dissipation condition of the relay goes bad,  and the temperature of the coil rises, which changes the given pull-in and release parameters of the relay, affecting the normal operation of the relay. The low air pressure can also reduce the insulation resistance of the relay. It is difficult to extinguish the arc and is easy to melt the contacts and affect the reliability of the relay. It can be used normally at an altitude of fewer than 2000 meters, and it needs capacitance derated used at an altitude of more than 2000 meters. 12. Reduce the impact of mechanical stress on the relay. Mechanical force mainly refers to stress such as vibration, impact, and collision on the control system. The self-vibration of the circuit breaker in the high-voltage switch and the vibration caused by the opening and closing operations has a greater impact on the relay. An intermediate relay with a balanced armature mechanism should be selected. Electromagnetic relays have cantilevered beam structure, the natural frequency is low, oscillation and impact will cause resonance, resulting in the relay contact pressure to drop and contact instant disconnection or contact vibration, which will affect the reliability of the relay. It suggests that vibration measures should be taken to prevent resonance. Ⅴ One Question Related to DC Relay5.1 QuestionHow Does a DC relay work?5.2 AnswerA DC relay uses a single coil of wire wound around the iron core to make the electromagnet. When the DC coil is energized, the magnetism generated in the core is steady because the DC just keeps going. The steady magnetism keeps the lever attracted as long as the DC is flowing. Ⅵ Frequently Asked Questions about How Relay Works1. What is a relay and how it works?A relay is an electrically operated switch. They commonly use an electromagnet (coil) to operate their internal mechanical switching mechanism (contacts). When a relay contact is open, this will switch power ON for a circuit when the coil is activated. 2. Why relay is used?The switch may have any number of contacts in multiple contact forms, such as making contacts, break contacts or combinations thereof. Relays are used where it is necessary to control a circuit by an independent low-power signal, or where several circuits must be controlled by one signal. 3. How do you know if a relay is working?The only tool required to check a relay is a multimeter. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 positions in the fuse box where the relay plugs in (or wherever the relay is located). 4. What is the main function of the relay?Relays are electric switches that use electromagnetism to convert small electrical stimuli into larger currents. These conversions occur when electrical inputs activate electromagnets to either form or break existing circuits. 5. What is the difference between relay and switch?The main difference between Relay and Switch is that the Relay is an electrically operated switch and Switch is an electrical component that can break an electrical circuit. ... Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. 6. Are Relays AC or DC?A Dc relay coil has a resistance that limits the dc current. An AC coil relies on its impedance for governing the current. An AC relay will remain contact closed due to mechanical inertia and a little mechanical hysteresis and, the fact that an alternating north and south pole both attract the relay armature. 7. How a relay works in a car?Although there are various relay designs, the ones most commonly found in low voltage auto and marine applications are electro-mechanical relays that work by activating an electromagnet to pull a set of contacts to make or break a circuit. These are used extensively throughout vehicle electrical systems. 8. What happens when a relay fails?If the ignition relay shorts burns out or otherwise fails while the engine is operating it will cut off power to the fuel pump and ignition system. ... In some instances of a faulty relay the vehicle will be able to restart once the relay cools off, only to stall out once again after the relay overheats. 9. Does a relay need constant power?The answer to that one is No. Relays have a finite lifetime in terms of how many times they can open and close. And limit to how much current they can handle. But keeping a relay constantly energized does not wear it out. 10. Why is a relay better than a switch?Relays are a better choice for switching large currents (> 5A). Relays can switch many contacts at once. Disadvantages of relays: • Relays are bulkier than transistors for switching small currents. Relays cannot switch rapidly (except reed relays), transistors can switch many times per second. Recommended ReadingBasic Knowledge of Relay Electronics Tutorial with VideoThe Role of the Relay and Its Working PrincipleThe Types of Common Relay and How to Choose Relay?

IntroductionTime relay refers to a kind of relay whose output circuit needs to make an obvious change (or contact action) after adding (or removing) the input action signal in a specified and accurate time. It is an electrical component used in a circuit with a lower voltage or a smaller current to switch on or off a circuit with a higher voltage and larger current.  With the development of electronic technology, electronic time relays have become mainstream products in time relays. Electronic intelligent digital display time relays using large-scale integrated circuit technology have many working modes, which can not only achieve long delay time but also have high time-delay accuracy, small size, convenient adjustment and long service life, making the control system simpler and more reliable. The time relay also has the function of automatic monitoring. Time relay and other equipment together can form a program space route to realize the automatic operation of the equipment.Time Relay Basics ExplainedCatalogIntroductionⅠ Time Relay Basics  1.1 What is a Time Delay Relay?  1.2 Time-delay Relay Working Principle  1.3 Timer Relay Structure  1.4 Timer Relay Parameters  1.5 Four-type Time Relay Contacts Ⅱ Understanding Time Delay in Relay CircuitⅢ Time Relay Classifications  3.1 According to Working Principle  3.2 According to the Delay ModesⅣ How to Wire Time Relay?Ⅴ Time Relay ApplicationsⅥ Time Relay SelectionⅦ Timer Relay Using Instructions  7.1 General Ideas  7.2 Two Points for Attention in Using Time RelaysⅧ Case Study: Time Relay Switch in Light CircuitⅨ Frequently Asked Questions about Time Delay Relay BasicsⅠ Time Relay Basics1.1 What is a Time Delay Relay?The time relay is a very important component in the electrical control system. In many control systems, use the time relay to achieve delay control. Time relay is an automatic control electrical appliance that uses the principle of electromagnetic or mechanical action to delay the closing or opening of contacts. Its characteristic is that there is a delay from the time the attracting coil gets the signal to the action of the contact. The time relay is generally used to control the motor starting process with time function. As above mentioned, the main function of the time delay is as an executive device in simple program control. When it receives the start signal, it starts timing. After the timing ends, its working contact opens or closes to promote the subsequent circuit work. Generally speaking, the delay performance of the time relay can be adjusted within the range of design, so as to facilitate the adjustment of its delay time. In addition, a time relay alone may not be able to do close. After closing for a period of time, it will open again. It is a cycle of time-delay closing and opening. However, configuring a certain number of time relays and intermediate relays can do it. 1.2 Time-delay Relay Working PrincipleTime relay is widely used in remote control, telecommunication, automatic control and other electronic equipment, and is one of the most important control components. When the coil is energized, the armature and the pallet are attracted by the core and move down instantaneously, making the action contact close or open. However, the piston rod and the lever cannot fall with the armature at the same time, because the upper end of the piston rod is connected to the rubber film in the air chamber.  When the piston rod starts to move downward under the action of the released spring, the rubber film is concave downward. The air in the air chamber becomes thinner, causing the piston rod to be damped and slowly descend. After a certain period of time, the piston rod descends to a certain position, and then the delay contact action is pushed through the lever to make the moving contacts open and close. The time from when the coil is energized to when the delay contact completes the action is the delay time of the relay. The length of the delay time can be changed by adjusting the size of the air inlet hole of the air chamber with a screw. After the suction coil is de-energized, the relay relies on the spring to recover. And the air is quickly expelled through the air outlet. 1.3 Time Relay StructureFigure 1. Air-damping Time Relay1 Coil5 Push plate9 Weak Spring13 Adjusting Screw2 Iron Core6 Piston rod10 Rubber Film14 Air Inlet3 Armature7 Lever11 Air Chamber Wall15 Micro Switch4 Reaction Spring8 Spring12 Piston16 Micro Switch 1.4 Time Relay ParametersTechnical parameters include rated voltage, contact working current, contact type and quantity, delay time, accuracy, ambient temperature, mechanical life and electrical life, etc. Now take the SJ23 series air-type time relay as an example, its technical parameters are as follows:1) Rated control capacity: AC300VA, DC60W (30W delay contact assembly).2) Rated voltage level: AC380V, 220V; DC220V, 110V.3) Rated voltage of the coil: AC110V, 220V and 380V.4) Maximum operating current of the contact: 0.79A at AC380V, 0.27A (momentary) and 0.14A (delay) at DC220V.5) Delay repeat error: ≤9%.6) Hot-state pull-in voltage: no more than 85% of the rated voltage of the relay. When the voltage drops from the rated value to 10% of the rated value in cold-state, it can be reliably released. And it can reliably release after reaching 110% of the rated voltage.7) The mechanical life is not less than 1 million times, and the electrical life is 1 million times (the DC life of the delay contacts assembly is 500,000 times). 1.5 Four-type Time Relay ContactsFigure 2. Time Relay SymbolsNOTC (normally-open, timed-closed): When the coil is not energized, the NOTC contact is normally open. It is closed by energizing the relay coil, but only within a specified time after the coil is continuously energized. The moving direction of the contact (close or open) is the same as that of a standard normally open contact. Since the delay occurs in the direction in which the coil is energized, this type of contact is normally open and on-delay. NOTO (normally-open, timed-open): Unlike the NOTC contact, the timed action occurs when the coil is de-energized. Since the delay occurs when the coil is de-energized, this type of contact is normally open and off-delay. NCTO (normally-closed, timed-open): When the coil is not powered on, the NCTO contact is normally closed. By energizing the relay coil, the contact is opened, but only within a specified time after the coil is continuously energized. The movement direction of the contact (closed or opened) is the same as the standard normally closed contact, but there is a delay in the opening direction. NCTC (normally-closed, timed-closed): The NCTC contact is similar to NCTO contact, because when the coil is normally closed when in de-energized and opened by energizing the coil. Ⅱ Understanding Time Delay in Relay CircuitSet delay time of a relay. Generally speaking, the delay performance of the time relay can be adjusted within the range of design, so as to facilitate the adjustment of its delay time in circuit. Time Delay Relay Circuit (Power-Off)If you are using an on delay relay, the delay will start immediately after the input signal is obtained. After the delay is completed, the executive part will output the signal to the control circuit. When the input signal disappears, the relay will immediately return to the pre-action status. It is opposite to an off delay relay. When the input signal is obtained, the execution part immediately has an output signal. After the input signal disappears, the relay needs a certain time to restore to the state before the action.Figure 3. Timer Relay StructureⅢ Time Relay Classifications3.1 According to Working PrincipleAccording to different working principles, time relays can be divided into air damping time relays, electric time relays, electromagnetic time relays, electronic time relays, etc. (1) Air damping time relayThe type is obtained by using the principle of damping when air passes through the small hole. Its structure is composed of three parts: electromagnetic system, delay mechanism and contact. The electromagnetic mechanism is a double-port direct-acting type, the contact system is a micro switch, and the delay mechanism adopts an airbag damper. (2) Electronic time relayUtilize the principle that the capacitor voltage in the RC circuit can't jump, and can only change gradually according to the exponential law, that is, the delay is obtained by electrical damping characteristics.Features: Wide delay range, high precision (generally about 5%), small size, shock resistance and easy adjustment. (3) Electric time relayUse the miniature synchronous motor to drive the reduction gear train to obtain the time delay.Features: The delay range is wide, up to 72 hours, and the delay accuracy can reach 1%. At the same time, the delay value is not affected by voltage fluctuations and environmental temperature.Its delay range and accuracy are unmatched by other time relays. Its disadvantages are complex structure, large size, short life, high price, and accuracy is affected by the power frequency. (4) Electromagnetic time relayUse the principle of slow attenuation of the magnetic flux after the electromagnetic coil is cut off to delay the release of the armature of the magnetic system to obtain the delay action of contacts. It is characterized by a large contact capacity, so the control capacity is large. However, the delay time range is small, and the accuracy is slightly worse. So it is mainly used in the control of DC circuits. 3.2 According to the Delay ModesBased on it, time relays can be divided into two types: on-delay type and off-delay type.(1) The on delay type time relay starts to delay immediately after receiving the input signal. After the delay is completed, its execution part outputs the signal to manipulate the control circuit. When the input signal disappears, the relay immediately returns to the state before the action.(2) The off delay type time relay is just the opposite. When the input signal is obtained, the execution part immediately has an output signal. After the input signal disappears, the relay needs a certain delay to restore to the state before the action. Ⅳ How to Wire Time Relay?The time relay is a very important component in the electrical control system. There are power-on delay types and power-off delay types. Based on the action type, there are electronic type and electric type, etc. Between them, the electronic type uses the principle of capacitor charging and discharging combined with electronic components to achieve delay action. There are many electric styles by using air bags and springs.Figure 4. Time Relay Wiring Schematics Time Relay Wiring:1) Control wiring: Consider it as a DC relay.2) Work control: Although the control voltage is connected, whether it plays a control role is determined by the timer on the panel.3) Function understanding: It is a switch,single-pole double-throw, with an active point, just like the active arm of a common knife switch.4) Load wiring: Connect the neutral wire of the power supply or the negative terminal.5) Working principle: When the timer is invalid, it is equivalent to the normal light in the switch-off state. When timing, the relay will act and the electrical appliances will be energized to work, which is equivalent to the normal light in the switch-on state.Take the power-on delay time relay as an example:Figure 5. On Delay Relay Contacts Wiring Ⅴ Time Relay ApplicationsIn Flash ControlTwo-time relays cooperate with each other to provide constant frequency on/off pulses of the contacts, sending intermittent power to the light.  In Furnace Safety Purge ControlBefore the combustion furnace can be safely ignited, the fan must run for a certain period of time to clean out any flammable or explosive steam in the furnace chamber. The time relay provides the required time parts for the furnace control work.In Electric Soft-start Delay ControlIt is not necessary to start a large electric engine by switching full power from a completely stopped state, and can reduce voltage softly start with less inrush current.In Conveyor Belt Sequence DelayWhen multiple conveyor belts are arranged to transport materials, the conveyor belts must be started in the reverse order (the last one is first, the first one is last) to prevent materials from accumulating on the moving conveyor which may be stop or move slowly. Ⅵ Time Relay SelectionThe selection of time relay is mainly due to delay mode and parameter coordination. The following aspects should be considered when selecting.(1) Delay mode selectionIt should be selected according to the requirements of the control circuit. The reset time after the action is longer than the inherent action time, so as to avoid misoperation or even no delay. This is especially important in the occasions of repeating delay circuits and frequent operations. (2) Type selectionFor occasions where the delay accuracy is not high, cheaper electromagnetic or air damping time relays are always used. On the contrary, for occasions where the delay accuracy is high, electronic time relays can be used. (3) Coil voltage selectionAccording to the voltage of the control circuit, the voltage at which the relay attracts the coil is selected. (4) Selection of power supply parametersIn the occasions where the power supply voltage fluctuates greatly, it is better to use air damping or electric time relays than the transistor type. And in the occasions where the power frequency fluctuates, electric time relays should not be used. In addition, when the temperature changes greatly, air damping type should not be used. When selecting a time relay, pay attention to the current type and voltage level of its coil (or power supply), and other factors, such as delay mode, contact form, delay accuracy and installation method according to the control requirements.Ⅶ Timer Relay Using Instructions7.1 General Ideas1) Keep the time relay clean, otherwise, the error will increase.2) Before use, check whether the power supply voltage and frequency are consistent with the voltage and frequency of the time relay.3) Choose the control time of the time relay according to user requirements. Regardless of the type of time relay, as long as the timing time is equal to the set time, its output contacts will act to achieve the purpose of the timing control circuit.4) For DC products, pay attention to wiring according to the circuit diagram and pay attention to the polarity of the power supply.5) After the time relay is out of working state, it should be reset immediately for the next use. If the repeated use interval is less than the preset time, the control circuit will be abnormal. What’s more, the power-on delay type is automatically reset after power off; and the power-off delay type is automatically reset after power on.6) Try to avoid using it in places with obvious vibration, direct sunlight, humidity and soil contact. 7.2 Two Points for Attention in Using Time RelaysThree Key Points1) Starting point of timingOn one hand, when selecting the timing point of the power-on delay time relay, you should choose to supply power to the time relay when the timing signal is sent by the control circuit that needs to perform timing. On the other hand, when selecting the timing point of the power-off delay type time relay, you should choose to cut off the power supply of the time relay when the control circuit that needs to send out the timing signal, so that the timing can be performed.2) Ending point of timingThe timing endpoint has two meanings: one refers to the point at which the set time is equal to the timing time; the other refers to the point at which the contract operates.3) Reset point of timingThe reset of the time relay is to clear the last timing content for the next use. If it is not reset, an abnormality will occur the next time it is used. Special attention should be paid to: the interval between two uses should be greater than the reset time, which is particularly important in electric time relays. The relationship between the starting point, ending point and reset point of timing1) After the time relay is used, there is a reset problem. Therefore, most of the control circuits are in the next level circuit by the time relay output. After the timing completion signal is accurately obtained, it is used to cut off the power supply of the time relay (power-on delay type), or power the time relay (power-off delay type).2) In the upper and lower control circuits of the time relay, there are components that cannot work at the same time. If the time relay cannot accurately operate the upper and lower control circuits at these points, it will cause the device to operate abnormally. Ⅷ Case Study: Time Relay Switch in Light CircuitControl requirements: Light 1 and light 2 are on at the same time, and light 2 is off in 30 seconds after light 1 is off. When light 1 is on, light 2 can be off at any time.According to the control requirements, explain through the following circuit diagram.Figure 6. Time Relay Switch in Light Circuit1) Press SB2, the contactor KM is energized and self-locked, and at the same time KT is also energized, and KT closes.2) After KT is turned on, the intermediate relay KA is also energized to work.3) At the same time, contact KM and contact KA are also closed at the same time, light 1 and light 2 are on.4) When the stop button SB1 is pressed, the contactor KM powers off, the contact KM opens, and the light 1 is off at the same time. Because of the existence of the power-off delay relay, KT is still on as well as the light 2. It goes out after the timing set by the time relay.5) When light 1 is on, and contact KA1 is turned on at any time, the time relay resets. KT disconnects and the light off.This is the typical application of an off delay relay. However, in the actual circuit, the control logic may be more complicated than this, so we must deeply understand the working principle and application of the time relay. Ⅸ Frequently Asked Questions about Time Delay Relay Basics1. What is time-delay relay?Time-delay, or time-release relays, allow necessary actions to happen at specific times in an electrical apparatus because they, in essence, act as a timer. 2. How does a time delay relay work?Time delay relays control the flow of electrical power and can be used to control power to many different types of electrical loads. Combining electromechanical output relay capability with control circuitry, these relays are pre-engineered to perform up to eleven time delay functions. 3. What is time delay relay circuit?Time Delay Relays. Time-Delay Relay. Relays are switches that are controlled by a circuit. Relays, in essence, send messages that tell something to start. When a car is started, the ignition only indirectly interacts with the battery of the car because a relay is sending the signal that tells the car to start. 4. How does a time delay relay work?Upon application of input voltage, the time delay relay is ready to accept trigger signals. Upon application of the trigger signal, the relay is energized and the preset time begins. ... Continuous cycling of the trigger signal at a rate faster than the preset time will cause the relay to remain energized. 5. How do you make a time delay relay?These relays provide a “Time Delay” between the energizing or de-energizing of the coil and movement of the armature. Such relays are called Time Delay Relays. A Time Delay Relay consists of a normal electromechanical relay along with a control circuit to control the relay operation and timing. 6. What is off delay relay?Abbreviated “NOTO”, these relays close immediately upon coil energization and open after the coil has been de-energized for the time duration period. Also called normally-open, off delay relays. 3: Normally-closed, timed-open. 7. How does an off delay timer relay work?Operation of Off Delay FunctionUpon application of input voltage, the time delay relay is ready to accept a trigger. When the trigger is applied, the output is energized. Upon removal of the trigger, the time delay (t) begins. At the end of the time delay (t), the output is de-energized. 8. What is the difference between off delay and on delay timer?As for Timer ON Delay, Timer starts by turning ON the timer trigger bit, and the timer output bit turns ON when the setup time has passed. As for Timer OFF Delay, the timer output bit turns OFF when the setup time has passed after the timer input bit had turned OFF. 9. How do you test a timer relay?Burden TestAdjust the timer with high time delay for example: 2 minutes.Energize the relay with 125V and measure the dc current.Note down the current before timer operates.After 2 minutes relay will pick up. Note down the current after operation.Calculate the relay power (W) = 125v x measured current. 10. What is the function of an time delay relay?Typical time delay functions include on-delay, repeat cycle (starting off), interval, off-delay, retriggerable one shot, repeat cycle (starting on), pulse generator, one shot, on / off delay, and memory latch.

IntroductionSemiconductor diode, also known as crystal diode, has obvious unidirectional conductivity. It is a kind of electronic components widely used in electrical equipment for protection, rectification, switching, and many other applications. So it is pretty common to see diodes in daily electronic circuits, such as Zener diodes, light-emitting diodes, photodiodes, etc. Therefore, it is necessary to know how to test whether a diode is properly working or not.How to Test a Diode Using a MultimeterCatalogIntroductionⅠ Diode Basics1.1 To Figure Out Diode Anode and Cathode1.2 What Would Cause a Diode to Fail?1.3 Common Diode Failures AnalysisⅡ How to Test Diode with a Multimeter?2.1 Digital Multimeter and Analog Multimeter2.2 Common Diodes Testing Rules2.3 Testing Methods of Types of DiodesⅢ Example Analysis3.1 Test a Diode in Circuit3.2 Power-off and Power-on Testing Methods3.3 ConclusionⅠ Diode Basics1.1 To Figure Out Diode Anode and CathodeThe anode and cathode of diode can be distinguished by screen printing on PCB board, which are as shown in the following:1) The notched end is the cathode of diode.2) The end with a horizontal bar is the cathode.3) The end with white parallel bars is the cathode.4) One end of the triangle arrow is the cathode.5) The small end of the plug-in diode is the cathode, and another big end is the anode.1.2 What Would Cause a Diode to Fail?The common reasons for a diode failure are open circuit, short circuit and unstable voltage regulation. Among these three types of failures, there may be signs. For example, the power supply voltage rises, the supply voltage drops to zero or the output is unstable. Therefore, specific problems must be analyzed in detail for the diode test.The common measurement tool for diode is a multimeter, including on-circuit measurement (the diode is on the circuit board) and off-circuit measurement (the diode is not on the circuit board). As for the basic principle of diode measurement, the forward resistance and the reverse resistance of the PN junction are measured, and the basic judgment is based on the values of them. Therefore, to do a good job in diode test, it is necessary to understand the basic structure and working principle of diodes, and then to understand the main fault characteristics of the diode. 1.3 Common Diode Failures Analysis1) open circuitThis means that the positive and negative electrodes of the diode have been disconnected, and the forward and reverse resistance of the diode have become infinite. After the diode is open, the circuit is in an open state.2) voltage breakdownThis means that there is a path between the positive and negative electrodes of the diode, and the forward and reverse resistance are as large as or close to each other(but not infinite). After a diode breaks down, the action between the positive and negative electrodes may always exit, because there are different manifestations in different circuits.3) forward voltageIf the forward resistance of the diode is too large, the voltage drop of the signal on the diode will increase, which will cause the output signal to decrease, and the diode will be damaged due to the heat. After the forward resistance becomes larger, the unidirectional conductivity of the diode will become poor.4) reverse voltageThe reverse resistance of the diode becomes smaller, which means the unidirectional conductivity of the diode be effected.5) performance degradationUnder this circumstance, the diode does not have obvious failures such as open circuit or breakdown. However, when the situation is getting worse, the stability of the circuit will deteriorate or the output signal voltage of the circuit will drop. Ⅱ How to Test Diode with a Multimeter?2.1 Digital Multimeter and Analog MultimeterWhen using a digital multimeter to test a diode, the red probe connects with the anode and the black probe connects with the cathode. At this time, the measured resistance is the forward conduction resistance of the diode, which is just the opposite of the test result of an analog multimeter. 2.2 Common Diodes Testing Rules(1) The forward resistance of the low-power germanium diode is 300Ω～500Ω, and the silicon diode is lkΩ or more. The former reverse resistance is tens of thousand ohms, and the latter is above 500kΩ (the value of high-power diode is smaller).(2) The polarity of the diode can be judged according to the resistance values (small forward resistance and large reverse resistance). Set the multimeter to the ohm block (Usually use R×100 or R×1k block, do not use R×1 block or R×10k block. The R×1 block is in a large current, it is easy to burn the tube, while using R×10k block may cause the tube broken down with high voltage). Connect the two polarities of the diode with the test probes respectively, and measure the two resistance values. When the measured resistance value is smaller, the end connected to the black lead is the anode. In the same way, when the measured resistance value is larger, the end connected to the black probe is the cathode. If the measured reverse resistance is small, it means that the diode is short-circuited, on the contrary, if the forward resistance is large, it means that the tube is open. In both cases, the diode can’t be work normally.(3) Silicon diodes generally have a forward voltage drop of 0.6V～0.7V, and the forward voltage drop of a germanium diode is 0.IV～0.3V. By measuring the forward voltage of the diode, it can be judged that the tested diode is a silicon tube or a germanium tube. This method is to connect a resistor (lkΩ) behind the power supply, and then connect with the diode according to the polarity characteristic to make the diode forward conducting. At this time, use a multimeter to measure the tube voltage drop. In addition, it is more convenient if it is used in energized dynamic measurement. 2.3 Testing Methods of Types of DiodesZener DiodesHow to test a Zener diode? The following here is to give some ideas.(1) Generally use the low-resistance block to test the Zener diode with a multimeter. Since the battery in the meter is 1.5V, this voltage is not enough to make the Zener diode reverse breakdown. So the forward and reverse resistance should be the same as a normal diode.(2) Measurement of the voltage stabilization value Vz of the Zener diode. When measuring diode, the power supply voltage must be greater than the stable voltage of the tube under test. In this way, the high-resistance block of the multimeter (R×10k) must be used. At this time, the battery in the meter has a higher voltage. When the multimeter's range is set to high barrier, measure diode reverse resistance. If the measured resistance is Rx, the voltage regulation value of the Zener diode is:In the formula, n is the override of the gear used. For example, if the highest electrical barrier ofR0 is the central resistance of the multimeter.E0 is the highest battery voltage value of the multimeter used.Example: Use an MF50 multimeter to measure a 2CW14 diode.R0=10Ω, the highest electrical barrier is R×10k.E0=15V, the measured reverse resistance is 75kΩ, then its voltage regulation value is:If the measured resistance is very large (close to infinite), it means that the voltage Vz under test is greater than E0, therefore, tube will not break down. If the measured resistance is very small (0 or only a few ohms), it means that the test probes are connected reversely, and then just swap the test probes. Light-emitting Diodes (LED)A light-emitting diode is a semiconductor device that converts electrical energy into light energy. It has the characteristics of small size, low working voltage and low working current.(1) There is a PN junction inside the light-emitting diode, so LED has the same characteristic of unidirectional conductivity. Its detection is similar to the measurement of ordinary diodes.(2) Use the R×1k or R×10k gear, and the forward and reverse resistance values are measured. Generally, the forward resistance is less than 50kΩ, and the reverse resistance is greater than 200kΩ.(3) The working current of the light-emitting diode is an important parameter. If the working current is too small, the light-emitting diode will not light up, and it is too large, the light-emitting diode will be easily damaged.(4) The forward turn-on voltage of the light-emitting diode is 1.2V ~ 2.5V, and the reverse breakdown voltage is about 5V. PhotodiodesPhotodiode is a semiconductor device that can convert light intensity into electrical signals.(1) There is a window on the top of the photodiode that can inject light, and the light irradiates the die through it. Under the excitation of the light, a large number of photoelectric particles are generated in the photodiode, which greatly enhances its conductivity and reduces internal resistance.(2) The photodiode is similar to the Zener diode. It also works in the reverse state, with reverse voltage.(3) The forward resistance of the photodiode does not change with the light. Its reverse resistance is larger when there is no light, and becomes smaller when it is exposed to light. That is, the stronger the light, the smaller the reverse resistance. Without light, the reverse resistance will return to the original value.(4) According to the related principle, use a multimeter to measure the reverse resistance of the photodiode. Change the light intensity when measuring, and observe the change of the reverse resistance of the photodiode. If there is no change or less change of the reverse resistance when light changes, it indicates that the tube has failed. High-speed Switching DiodesThe method of detecting high-speed silicon switching diodes is the same as that of ordinary diodes. The difference is that the forward resistance of this tube is relatively large. Measuring with Rxlk block, the forward resistance value is 5k ~ 10k in general, and the reverse resistance value is infinite. Fast Recovery Diodes / Ultrafast Recovery DiodesDetecting fast recovery and ultra-fast recovery diodes with a multimeter is basically the same as that of detecting plastic-encapsulated silicon rectifier diodes. That is, first use the Rxlk block to test its unidirectional conductivity. Generally, the size of forward resistance is about 4 ~ 5k, and the reverse resistance is infinite. And then use the Rxl block to repeat the test, at this time, the forward resistance is several ohms, and the reverse resistance is still infinite. DIAC (Diode for Alternating Current) DiodesUse the Rxlk block, and measure the forward and reverse resistance values of diac, which should be infinite. If the test probes are exchanged to measure, the pointer swings to the right, which indicates that the test tube has a leakage fault. Another method is placing the multimeter in the DC voltage block. During the test, shake the megohmmeter, and the voltage value indicated by the multimeter is the VBO value of the tube. Then change the two pins of the tested tube, and measure the VBR value in the same way. Finally, compare VBO and VBR. The smaller the difference between the absolute values of the two, the better the symmetry of the diac diode. TVS DiodesFor the dual TVS, resistance values between the two pins should be infinite when the red and black test probes of multimeter are exchanged at random. Otherwise, the tube has poor performance or has been damaged. High-frequency Varistor Diodesa. Identify Diode PolarityThe difference between high-frequency varistor diodes and ordinary diodes is that their color code is different. It is generally black of ordinary diodes, while high-frequency varistor diodes’ is light. Its polarity rule is similar to that of ordinary diodes. That is, the end with the green ring is the cathode, otherwise it is the anode.b. Measure Forward and Reverse ResistanceThe specific method is the same as the method of measuring ordinary diodes. Using the Rxlk block of a AM-500 multimeter, the forward resistance is 5k～55k, and the reverse resistance is infinite. Varactor DiodesUsing Rx10k block, no matter how the red and black test leads are exchanged for measurement, the resistance between the two pins of the varactor diode should be infinite. During the measurement, if the multimeter swings slightly to the right or the resistance value is zero, it means that the varactor diode under test has a leakage fault or has been broken down. No matter the loss of varactor diode capacity or internal open-circuit fault, it is impossible to detect them with a multimeter. When necessary, the replacement method can be used for inspection to make judgment. Infrared Light Emitting Diodes (IRED)Put the multimeter in the Rxlk block and measure the forward and reverse resistance of the IRED diode. Generally, the forward resistance should be about 30k, and the reverse resistance should be above 500k. It means the tube can work normally. The larger the reverse resistance, the better. IR Receiver Diodesa. Appearance Identification: Diode Cathode / Anode(1) Common infrared receiving diodes are black in appearance. In addition, there is a small oblique plane at the top of the tube body of the infrared receiving diode. Usually, the pin with one end of the oblique plane is the negative pole and the other end is the positive pole.(2) Use the Rxlk block to test the resistances between two pins. When a diode works normally, the resistance value of two pins are different. And exchange the test leads several times to get some pairs of values. According to the smaller resistance value, the pin connected to the red probe is the cathode, and the pin connected to the black probe is the anode.b. Performance DetectionUse a multimeter to measure the forward and reverse resistance of the infrared receiving diode. According to the resistance values, whether the diode is damaged can be judged preliminarily. Laser DiodesUse the Rxlk block of multimeter, and determine the order of the pins of the laser diode according to the method of detecting ordinary diodes. Because the forward voltage drop of the laser diode is larger than that of the ordinary diode, when detecting the forward resistance, the pointer of the multimeter is slightly deflected to the right, and the reverse resistance is infinite. Unijunction Transistor (UJT)a. Discrimination of ElectrodesBased on the R×1k block, use two meter pens to measure the forward and reverse resistance between any two of the three electrodes ( base B1 and base B2, and emitter E) of the ujt diode. The measured resistance values between the two electrodes are both 2~10kΩ, in addition, B1 and B2 will be different.b. Performance JudgmentThe performance of an ujt diode can be judged by measuring whether the resistance between its pins is normal. Use the R×1k barrier, the black test lead connect to the emitter E, and the red test lead connect to the two base electrodes in turn. Normally, a resistance value should be several thousand to ten thousand ohms. On the contrary, the red test lead connects to the emitter E, and the black test lead connects to the two base electrodes in turn, and the resistance should be infinite under normal conditions. The forward and reverse resistance values between the two bases are both in the range of 2~10kΩ. If they differ greatly from the normal value, the diode is damaged. Ⅲ Example Analysis3.1 Test a Diode in Circuita. Diode Test UsingAnalog MultimeterThe following measurements are all based on silicon diodes. If it is a germanium diode, the forward and reverse resistance of the diode will decrease.1) Measure forward resistance FRThe following figure is a wiring schematic diagram for measuring the forward resistance of a diode with an analog multimeter:Give the result as follows:IndicatorDescriptionUse the R×1k block to measure the diode, the forward resistance is several thousand ohms, and the pointer indicates stability. If the pointer swings slightly, it indicates that the thermal stability of the diode is poor.If the pointer indicates hundreds of kiloohms when measuring the forward resistance, it means that the diode is open.If the pointer indicates tens of kiloohms, it indicates that the diode has a large forward resistance and poor diode performance. Description of measurement of forward resistance:Forward Resistance (FR)DescriptionThousands of ohmsNormalZero or much less than a few thousand ohmsBreakdownHundreds of kilosLarge FR, the diode is openDozens of kilohmsLarge FR, bad forward characteristicsThe pointer is unstablePoor stability 2) Measure reverse resistance RRThe following figure is a wiring schematic diagram for measuring the reverse resistance of a diode with an analog multimeter:Give the result as follows:IndicatorDescriptionWhen measuring the reverse resistance, the value should be several hundred kiloohms. The larger the resistance value is, the better the indicator should be stable.If the reverse resistance is only a few thousand ohms, it means that the diode has broken down and has lost its unidirectional conductivity. Description of measurement of reverse resistanceReverse ResistanceDescriptionHundreds of kilosNormalZeroBreakdownMuch less than a few hundred thousand ohmsDiode’s reverse characteristic is not good.Pointer does not moveThe diode is open. Note: The reverse resistance of some diodes is very large, at this time, it is not certain that the diode is open, so that its forward resistance should be measured. If the value is normal, it means that the diode is not open.Pointer is unstableThe pointer cannot be stabilized at a certain resistance value during measurement, indicating that the diode has poor stability. 3.2 Power-off and Power-on Testing MethodsDiode in-circuit measurement is divided into two situations: Power-off and Power-on statea. Power-off MeasurementThere are something should be noted the method of this test.The influence of the external circuit on the test result is the same as the resistance and capacitance measured of internal circuit. And the influence of the measured forward resistance by the external circuit is lower than the reverse resistance.If there is any doubt about the measuring result, the diode should be removed from the circuit and measured separately. b. Power- on MeasurementWhen the circuit board is powered on, the test point is the tube voltage drop. Because the diode has a very important characteristic: when it is turned on, the tube voltage drop is basically unchanged. So the voltage drop is normal after being turned on, that is to say, the diode is normal.Measurement method: The diagram below shows the connection diagram of the tube voltage drop after the diode in the DC circuit. Setting multimeter in DC voltage 1 V block, the red probe is connected to the cathode of the diode, and the voltage indicated is the forward voltage drop of the diode. Diode forward voltage drop measurement results are analyzed as follows:DiodeDescriptionSilicon diode0.6VThe diode is normal and in a forward conducting state.> 0.6VThe diode is not in the conducting state.Close to 0The diode is in a breakdown state, the current in the loop will increase.Germanium diode0.2VThe diode is normal and in a forward conducting state.> 0.2VThe diode is off or is faulty.Close to 0In the breakdown state, the loop current increases significantly, without unidirectional conductivity. 3.3 ConclusionThe following points should be noted when measuring diodes:1) The diode in AC is in the cut-off state, because the diode is in the reverse state, and the reverse voltage at both ends is very large. The average voltage across the diode measured by the DC block is negative at this time.2) Use different blocks of the same multimeter to measure positive and negative resistance of one diode, their values will different. The forward and reverse resistances of the same diode measured with different multimeters are also different.3) When measuring the forward resistance of a diode, if the pointer cannot stop at a certain resistance value and constantly swings, it indicates that the thermal stability of the diode is not good.4) Some multimeters will provide a “diode check” function that displays the actual forward voltage of the diode when its conducting current. Such meters typically indicate a slightly lower forward voltage than what is “nominal state” for a diode, due to the very small amount of current used during the measurement. Frequently Asked Questions about Diode Test1. What is a diode test?A diode is best tested by measuring the voltage drop across the diode when it is forward-biased. ... A multimeter's Diode Test mode produces a small voltage between test leads. The multimeter then displays the voltage drop when the test leads are connected across a diode when forward-biased. 2. How do you test a rectifier diode?Touch the red (positive) probe of the multimeter to the positive terminal of the diode closet to the welder case interior. Touch the black (negative) probe of the multimeter to the negative terminal of the same diode. The multimeter should read a resistance between 0 and 1 ohm, or the diode is faulty. 3. How can you tell if a diode is positive or negative?Sometimes it's easiest to just use a multimeter to test for polarity. Turn the multimeter to the diode setting (usually indicated by a diode symbol), and touch each probe to one of the LED terminals. If the LED lights up, the positive probe is touching the anode, and the negative probe is touching the cathode. 4. How do you test a Schottky diode?Connect the red positive test lead to the anode of the Schottky diode and the black common test lead to the cathode of the diode. Listen for a “beep” or a “buzz” from the multimeter. If the Schottky diode responds as expected, the multimeter will sound a tone. 5. Can I test a diode in circuit?A diode is best tested by measuring the voltage drop across the diode when it is forward-biased. A forward-biased diode acts as a closed switch, permitting current to flow. A multimeter's Diode Test mode produces a small voltage between test leads. ... Voltage may be present in the circuit due to charged capacitors. 6. How do you check a diode?Diode PolarityThe polarity of both diodes is indicated with a stripe on one end of the body. The stripe corresponds to the line in the schematic symbol, indicating the cathode. The other end (no stripe) is the anode, indicated by the triangle in the schematic symbol. 7. What happens when a diode fails?However, a failed diode can short out too. In this case, the diode will exhibit a small resistance in both directions. The common reasons for a diode failure are excessive forward current and a large reverse voltage. Usually, large reverse voltage leads to a shorted diode while overcurrent makes it fail open. 8. How can you tell if a diode is blown?Turn the dial to “diode test” mode.This level of current is high enough to produce a reading, yet not so high that the diode will fail. It may also be labeled as “diode check” on your multimeter and is usually indicated by a small diode symbol. The diode symbol will look like a triangle pointing towards a line.