The Kynix Blog

Do you know graphene? Graphene is made of a single layer of carbon atoms that are bonded together in a repeating pattern of hexagons,it is one million times thinner than paper,so thin that it is actually considered two dimensional. Nowadays more and more electronic components are made of graphene such as solar cells,transistors or transparent screens cause it can help computing performance continue to grow.After a brief introduction of graphene,let's go into the subject--graphene sensors.  As far as we concern,graphene's ability to detect a variety of chemical and biological molecules would seem to make it a perfect match for sensors,however, graphene is hard to fashion the material into a transistor that can be turned on and off cause it's a conductor and lacks an inherent band gap. In order to make a sensor out of graphene, you need to use multiple layers of the material, which leads to high levels of electronic noise and reduces its effectiveness. Now, an international team of researchers has proposed a graphene-based semiconductor device that reduces electronic noise when its electric charge is neutral (referred to as its neutrality point). The group achieved this neutrality point without the need for bulky magnetic equipment that had previously prevented these approaches from being used in portable sensor applications.The researchers used their new sensing scheme to detect HIV-related DNA hybridization at picomolar concentrations.Scientists have fabricated a charge detector out of graphene that can detect very small amounts of charges close to its surface. The sensing principle of the device relies on charge species detection through the field-effect, which brings about a change in electrical conductance of graphene upon adsorption of a charged molecule on the sensor surface. According to Wangyang Fu, the author of the paper and a postdoc at the University of Leiden in the Netherlands,"Graphene is perfect for such application,it's unique among other solid state materials in that all carbon atoms are located on the surface,making the graphene surface highly sensitive for detection of changes in the environment." However, Fu notes that our ability to create practical electrochemically gated graphene-based field-effect transistors to detect charged species also requires a small amount of electronic noise, the existence of which fundamentally limits a sensor’s resolution."I believe we have discovered an elegant and simple approach to improve the sensitivity of next generation graphene electronic biochemical sensor devices,” said Fu. “Our device is able to function at its low-noise neutrality point without the need for complicated magnetic equipment that other approaches using graphene have depended upon.”Fu added.  "The electronic noise can be reduced without compromising the sensing response, enabling significant improvement to the signal-to-noise ratio compared to that of a conventionally operated graphene transistor to measure conductance." Fu added. This noise reduction and maintaining of the sensing response is achieved by making use of one of the unique properties of graphene field-effect transistors: its ambipolar (being both n- or p-type) behavior near the neutrality point.The neutrality point manifests itself in graphene as the lowest point of conductance in the material and is the result of graphene’s unique electronic band structure. At this low conductance point, the graphene sensors can operate at a lower noise level. While this doesn’t compromise the sensing response, it does lower the signal-to-noise ratio of the device, resulting in an overall improved sensing response.Another feature of the latest device is the use of so-called in-situ 'electrochemical cleaning' to ensure a clean graphene surface, which is a new technique meant to enable graphene electronic biosensors to provide reliable performance. While they were able to test their sensing scheme on HIV, more work must be done before this device could find its way into the next generation of biochemical sensors. First of all, Fu believes that there is a need to scale up the miniaturized graphene electronic arrays. In addition, microfluidic or nanofludic liquid handling should also be integrated into the arrays.He says there will also be a need for on-site electrochemical cleaning on each of the devices and the more surface functionalization to suit different cases of biomolecule detection. “Finally, on-chip read-out circuits and false detection evaluations are needed to evaluate sensor performance under different conditions,” he adds.\ In continuing research, Fu and his colleagues intend to adopt this low-noise technology for other single molecule detection methods and evaluate the sensor performances when scaled up. Finally,let's look forward to seeing the new era of new sensor soon. 

In this article, we will provide you the basic information of relay: what is a relay? What types of relays are there? What are their characteristics? How to maintain the common faults of the relay? With these questions, let us find the answers in the article together.     Catalog     I. What is a Relay?     1.1 Electrical Symbol     1.2 Contact Form     1.3 Functions of Relay II. Relay Classification III. Main Types of Relay IV. How to Test a Relay V. Influencing Factors of Relay Reliability VI. Maintenance of Common Faults of Relay VII. Example Explanation: Delay Relays FAQ   I. What is a Relay? This video will explain what is a relay, and how does a relay works with basic information about construction and different types of relay.   Relay is a kind of electric control device. When the change of input quantity (excitation quantity) reaches the prescribed requirement, the controlled quantity will be changed step by step in the electric output circuit. It has an interactive relationship between the control system (also known as the input loop) and the controlled system (also known as the output loop). Usually used in an automatic control circuit, it is a kind of automatic switch which uses a small current to control the operation of a large current. Therefore, it can play the role of automatic regulation, safety protection, conversion circuit, and so on.   1.1 Electrical Symbol A relay is composed of two parts: coil and contact group, the graphic symbol of the relay in a circuit diagram also includes two parts: a box for coil and a set of contact symbols for contact combination. When the contact circuit is relatively simple, the contact group is often drawn directly on one side of the circle frame, which is called centralized representation.   Relay coils are represented by a rectangular symbol in the circuit, and if the relay has two coils, draw two side-by-side boxes. The contacts of relays are represented in two ways: one is to draw them directly on the side of the box, which is more intuitive. The other is to draw each contact point into its own control circuit according to the need for circuit connection. Usually, the contact of the same relay is marked with the same text symbol, and the contact group is numbered to show the difference.   1.2 Contact Form There are three basic forms of contact for relays: 1. The two contacts are disconnected when power off, and the two contacts are closed when power on.   2. The two contacts are closed when power off and the two contacts are disconnected when the power on.    3. The contact group has three contact points, that is, a moving contact in the middle and a static contact in the upper and lower parts of the contact group, respectively. When the coil is power-off, the dynamic contact is disconnected from one of the static contacts and connected with the other. After the coil is power-on, the dynamic contact moves, the connecting contacts state is opposite to the power-off state to achieve the purpose of conversion. Such contact groups are called switching contacts.      1.3 Functions of Relay Relay is an automatic switching element with an isolation function. It is widely used in remote control, telemetry, communication, automatic control, electromechanical integration, and power electronic equipment. It is one of the most important control components.   The relay generally has induction parts (input section) that can reflect a certain input variable (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, light, etc.); an executing part (output section) capable of realizing power-on and power-off state of the controlled circuit. Between the input port and the output port of the relay, there is also an intermediate mechanism (driving section) for coupling the input, the function processing, and the driving of the output.   As a control element, relays generally have the following functions:   1) Expand the control range: for example, when the control signal of the multi-contact relay reaches a certain value, the multi-circuit can be switched on and off at the same time according to the different connecting forms of the contact group.   2) Amplification: a very small volume can control a large power circuit, such as sensitive relays, intermediate relays, etc.   3) Synthesis signal: when a plurality of control signals input multiple winding relays in the prescribed form, a predetermined control effect can be achieved by comparing and synthesizing.   4) Automatic, remote control, monitoring: relays on the automatic device, together with other electrical appliances, can form a program control circuit to achieve automatic operation.   II. Relay Classification   1. According to the working principle or structural characteristics of relays: 1) Electromagnetic relay: an electrical relay that is driven by the suction of an input circuit between an electromagnet core and an armature. 2) Solid relay: a relay in which electronic components perform their functions without mechanical movement, and the input and output are isolated. 3) Temperature relay: a relay that operates when the external temperature reaches a certain value. 4) Reed relay: a relay operates by a reed that is sealed in a tube and has a dual action caused by the electricity action on the reed and the armature. 5) Time relay: When the input signal is added or removed, the output part needs to be delayed or limited to a specified time to close off. 6) High-frequency relay: a relay used for switching a high frequency, a radio frequency circuit which had a minimum loss. 7) Polarization relay: a relay driven by magnetic field synthesis caused by a polarized magnetic field and a controlled current acting through the magnetic field generated by the control coil. The direction of the operating relay depends on the direction of the current flowing through the control coil. 8) Other types of relay: optical relay, sound relay, thermal relay, instrument relay, Hall effect relay, differential relay, etc.   2. According to shape size of relays: 1)miniature relay  2)subminiature relay 3)small miniature relay Note: for sealed or enclosed relays, the size is the maximum of the three vertical dimensions of the relay body, excluding the dimensions of mounting, leading end, rib pressing, edge pressing, flanging, and sealing solder joint.   3. According to the load of the relays: 1) micro power relay 2) small power relay 3) medium power relay 4) high power relay    4. According to the protective characteristics of relays: 1) sealed relay  2) enclosed relay 3) unenclosed/ open relay   5. According to the principle of action: 1) electromagnetic type 2) induction type 3) rectifier type 4) electronic type 5) dig type   6. According to the physical quantity of the reaction: 1) current relay 2) voltage relay 3) power relay 4) impedance relay  5) frequency relay 6) gas relay   7. According to the role of relays in the protection circuit: 1) starting relay  2) measuring relay  3) time relay 4) auxiliary/intermediate relay 5) signal relay 6) exit relay    III. Main Types of Relay   1) electromagnetic relay As long as a certain voltage is added at both ends of the coil, a certain current will flow through the coil, producing an electromagnetic effect, and the armature will contact the iron core under the action of electromagnetic force attraction, thus driving the armature dynamic contact and static contact (normally open contact) suction. When the coil is powered off, the electromagnetic suction also disappears, and the armature will return to its original position in the reaction force of the spring and release the dynamic contact from the original static contact (normally closed contact). In this way to achieve the purpose of switching on and off. In addition, it can be distinguished the "normal open and closed contacts of the relay.   Note: The static contact in the broken state when the coil is powered off is known as the "normal open-contact"; the static contact in the on-state is called the "normal closed-contact". Relays generally have two circuits, a low-voltage control circuit, and a high-voltage working circuit.   2) solid-state relay  A solid-state relay is a kind of four-terminal device with two connection terminals as input and the other two as output. In the middle, an isolation device is used to realize the electrical isolation of the input and output.   Solid-state relays can be divided into AC type and DC type according to the type of load power supply. According to the switch, type can be divided into normal open type and normally closed type. According to the isolation type, it can be divided into hybrid type, transformer isolation type, and photoelectric isolation type, and the photoelectric isolation type is the most.   3) thermal reed relay A thermal reed relay is a new type of thermosensitive switch which uses thermosensitive magnetic material to detect and control temperature. It consists of a temperature-sensitive magnetic ring, constant magnetic ring, reed tube, heat conduction mounting sheet, a plastic substrate, and other accessories. Thermal reed relays do not use coil excitation but are driven by magnetic forces generated by constant magnetic rings. In addition, whether the constant magnetic ring can provide magnetic force to drive the reed tube is determined by the temperature control characteristic of the temperature sensing magnetic ring.     4) reed relay Reed relay is a kind of coil sensing device, which uses a coil to produce a magnetic field to drive a magnetic reed tube. In addition, the characteristics of reed relays include small size, lightweight, fast reaction speed, short jump time, and so on.   When a whole piece of ferromagnetic metal or other conductive material is close to it, turn on or turn off the circuit. Reed relay consists of a permanent magnet and a reed tube. Both of them fixed to a bracket without magnetism or magnetic conduction. Take the line of the permanent magnet's north-south pole as the axis, which should be coincident or basically coincident with the axis of the reed. From far to near, adjust the distance between the permanent magnet and the reed tube, and fix the position of the magnet when it happens to move (turning off for normally open reed tube and turning on for normally closed reed tube). At this point, when there's a whole piece of magnetic material, and when the iron plate is close to the magnet and the reed tube at the same time, the reed tube will move again and return to the state without magnetic field action; when the iron plate leaves, the spring tube will move in the opposite direction. The reed relay has a strong structure, sealed contact, and high durability. It can be used as a position limiting switch for mechanical equipment, and can also be used to detect whether iron doors, windows, etc.    5) optical relay An optical relay is a semiconductor relay used in AC/ DC, refers to the integration of light-emitting and light-receiving devices. The input side and the output side are electrically insulated, but the signal can be transmitted through the optical. Its characteristics are semi-permanent, micro-current, high impedance, insulating, voltage-resistance, ultra-small, optical-transmission, contact-free, and so on.   It is mainly used in measuring equipment, communication equipment, security equipment, medical equipment, and so on. 6) time relay Time relay is a kind of control apparatus that uses electromagnetic principle or mechanical principle to realize time delay control. There are many kinds of it, such as air damping type, power-driven type, and electronic type.   Air damping time relay is often used in AC circuit, which uses the principle of air throttling through orifice compensation to obtain delay action. It consists of an electromagnetic system, delay mechanism, and contact. Time relay can be divided into two types: power-on delay type and power-off delay type.   The time delay range of the air-damping time relay is large (0.4~60s and 0.4~180s). Its structure is simple, and its accuracy is low. When the coil is electrified (voltage specification is ac380v, ac220v or dc220v, dc24v, etc.), the armature and bracket are attracted by the iron core and moved down instantly, so that the instantaneous action contact is turned on or off, and meanwhile, the piston rod and lever cannot fall with the armature at the same time, because the upper end of the rod is attached to the rubber film in the air chamber, and when the rod begins to move downward under the action of the released spring, the rubber film falls downward. Air becomes thin in the upper air chamber and the damping piston rod drops slowly. After a certain period of time, the piston rod drops to a certain position, then pushes the delay contact action through the lever, causing the dynamic break contact to break and the dynamic close contact turned off. From the coil to the delay contact to complete the action, this time is the delay time of the relay. The delay time can be changed by adjusting the size of the air chamber inlet hole. After the suction coil is powered off, the relay is restored by the action of the recovery spring, and the air was ejected quickly through the vent hole. 7) auxiliary relay a. characteristics of auxiliary relay:   The relay is composed of several high-quality sealed small relays with low coil voltage, which is damp-proof, dust-proof, non-breaking, high reliability, and overcomes the shortcomings of the electromagnetic auxiliary relay wire which is too thin and easy to break. Low power consumption, low-temperature rise, no need to attach high-power resistance, easy installation and connection, large capacity of a relay contact, long working life, easy to observe on the spot, and so on. The delay only needs to be adjusted by the dial switch on the panel, the delay precision is high, and the delay range can be set freely in 0.02S~ 5.00S.   Purpose of intermediate relay: auxiliary relay is used in various protection and automatic control lines to increase the number of contacts and the capacity of contacts in the protection and control loop.   b. classification of auxiliary relays:   static auxiliary relay   delay auxiliary relay   electromagnetic auxiliary relay   elevator auxiliary relay   rail auxiliary relay   c. auxiliary relay principle   When the coil is electrified, the moving iron core is absorbed under the action of the electromagnetic force, and the moving contact action is driven so that the normally closed contact is separated and the normally open contact is closed. When the coil is powered off and the moving iron core drives the dynamic contact to reset under the action of the spring. The working principle of the relay is that when a certain input (such as voltage, current, temperature, velocity, pressure, etc.) reaches a predetermined value, it operates. In order to change the working state of the control circuit, so as to achieve the established purpose of control or protection. In this process, the relay mainly plays a role in the transmission of the signal.   d. function of the auxiliary relay   The general circuit is often divided into two parts of the main circuit and a control circuit. The relay is mainly used for a control circuit, and the contactor is mainly used for the main circuit. Through the relay, using one control signal can control the other one or several signals, and the control of starting, stopping, linkage, and so on. The main control object is a contactor, the contact of the contactor is relatively large, and the carrying capacity is strong, but the control of weak current too strong electricity can be realized through the contactor, and a control object is an electric appliance.   1. Replace small contactor   The contact of the auxiliary relay has a certain load capacity. When the load capacity is small, it can be used instead of the small contractor, such as the electric shutter and the control of some small appliances. This advantage is that not only can play the purpose of control, but also can save space so that the electrical control part of the more refined.   2. Increase the number of contacts   This is the most common use of auxiliary relays, for example, in a circuit control system where a contact needs to control multiple contactors or other components, adding an auxiliary relay to the line.   3. Increase contact capacity   We know that although the contact capacity of the auxiliary relay is not very large, it also has a certain capacity with load, and the current required for its drive is very small. Therefore, the auxiliary relay can be used to expand the contact capacity. For example, it is not possible to use induction switches directly and the output of the transistor to control the heavy load of electrical components. In fact, the auxiliary relay is used in the control line, and the other load is controlled by the auxiliary relay to enlarge the control capacity.   4. Convert pin type   In the industrial control circuit, it is often necessary to use the normally closed contact of the contactor to achieve the control purpose. However, the normally closed contacts carried by the contractor are not enough to achieve the control task. At this time, an auxiliary relay can be parallel to the original contactor coil, and the corresponding components can be controlled by the normally closed contact of the auxiliary relay, and the contact type can be transformed to achieve the desired control purpose.   5. As a switch In some control circuits, intermediate relays are often used to turn on and off some electrical components, such as automatic demagnetization circuits common in color televisions or displays, and transistor controls the on and off of intermediate relays, which are controlled by the opening and closing of their contacts, such as color televisions or displays. So as to control the demagnetization coil on-off action.   6. Switching voltage   7. Eliminating interference in the circuit   8. Power direction relay   An electrical appliance that causes the controlled output circuit to be switched on or off when the input (such as voltage, current, temperature, etc.) reaches a specified value. It can be divided into two categories of electrical volume (such as current, voltage, frequency, power, etc.) relay and non-electrical volume (such as temperature, pressure, speed, etc.) relay. It has the advantages of fast movement, stable work, long service life, small volume, and so on. Widely used in power protection, automation, motion, remote control, measurement, and communication devices.       Common Types   1. overcurrent relay The overcurrent relay is a relay that operates from the current beyond its set value and can be used as a system line and overload protection. The most commonly used is an induction type overcurrent relay, which is opposite to the rotating disk of aluminum or copper by an electromagnet. The rotating disc is rotated by means of the electromagnetic induction principle so as to achieve the protective effect.   action principles:   The inductive overcurrent relay uses the secondary current of the current transformer to generate a magnetic field in the relay to cause the disk to rotate, but the current flowing through the relay must be greater than the current value of a certain current to rotate.   2. overvoltage relay  Overvoltage relay, its main purpose is that when the abnormal voltage of the system rises to more than 120% rating, the overvoltage relay operates so that the circuit breaker can jump off and protect the electric equipment from damage. The construction and operation principle of induction overvoltage relay are similar to those of overcurrent relay, except the main loop.   3. under voltage relay The under voltage relay is constructed in the same way as the overvoltage relay, except that the inner contact and the turntable turn immediately when the voltage is applied.   4. ground overvoltage relay The grounding overvoltage relay has the same structure as the overvoltage relay, and uses a three-phase three-wire non-grounding system, and is connected to the earthing transformer with an open triangle earthing to detect zero-phase voltage.   5. grounding overcurrent relay Grounding overcurrent relay, abbreviated as GCR, is a kind of high-voltage line earthing protection relay.   Main uses:   1) grounding overcurrent protection of high resistance grounding system.   2) grounding protection of generator stator winding.   3) layer short circuit protection of phase-separated generator.   4) overheat protection of grounding transformer.   6. selective grounding relay Selective grounding relay, also called directional grounding relay, is used in non-grounding systems to protect distribution lines. In addition, it can also be used in overhead lines and cable systems.   Selective grounding relay: if a zero-phase sequence current is detected by a grounding voltage transformer when a line is grounded, the selective grounding relay can accurately detect the fault line and alert it and disconnect it according to the requirement. And then continue to send electricity to the normal operating line.   7. free-phase relay In the three-phase line, phase-failure relay or phase-failure protection relay will burn out the single-phase operation of the motor if it does not cut off the line immediately when there is a one-wire break in the power supply end and causes the single-phase.   8. percentage differential relay A percentage differential relay is used as the AC motor of the transformer. Alternator with differential protection and over-current protection relay used as the protection devices, and when abnormal current generated by external fault flows over protection equipment, if current on the transformer is unbalanced or inconsistent with the characteristics of the current transformer, in these cases, this phenomenon will extend several times and cause failure operation to the relay.     IV. How to Test a Relay Relay is the key device in the intelligent prepaid electric energy meter, the life of the relay determines the life of the meter to a certain extent, thus the performance of the relay is very important to the operation of the intelligent prepaid electric energy meter. There are many manufacturers of relays around the world. Their production scale is quite different, the technical level and performance parameters are very different. Therefore, the manufacturers of electric energy meters must have a set of perfect testing devices when detecting and selecting relays. To ensure the quality of the meter. At the same time, the national power grid has also strengthened the sampling detection of the relay performance parameters in the intelligent electric energy meter, which also needs the corresponding testing equipment to check the quality of the meter produced by different manufacturers. However, at present, relay testing equipment is not only a single test item, but detection process also can not be automated completely, the detection data needs manual processing and analysis, the detection results are random, artificial, and the detection efficiency is low, in addition, there is no guarantee of safety.   According to the test requirements of relay performance parameters, the test items can be divided into two categories: one is the test items without load current, such as operating value, contact resistance, service life; the other, test items with load current, such as contact voltage, electrical life, overload capacity.   1.Measuring coil resistance: the multimeter R×10Ω barrier can be used to measure the resistance value of the relay coil, so as to judge whether there is an open circuit phenomenon in the coil. The resistance value of the relay coil is closely related to its working voltage and current. And the service voltage and working current can be calculated by the resistance value of the coil.   2. Contact resistance measurement: using the resistance barrier of the multimeter, the resistance value of the normally closed contact and the moving point resistance should be 0, and the resistance value of the normally open contact and the moving point shall be infinitely large. From this, you can distinguish between the normally closed contact and the normally open contact.   3. Measure the pull-in voltage and current: using an adjustable voltage stabilizing power supply and ammeter, input a set of voltages to the relay, and connect the ammeter in the power supply circuit to monitor. Slowly raise the power supply voltage and note down the pull-in voltage and current when the relay absorbs sound. To be accurate, you can try a few more times and get the average value. Measurement of release voltage and discharge current: it is also like the above-mentioned connection test, when the relay suction, then gradually reduce the power supply voltage, when heard the relay again release sound, note the voltage and current at this time, in addition, you can also try more than a few times to get an average release voltage and current. Generally, the release voltage of the relay is about 10% of the pull-in voltage, and it will not work properly if the release voltage is too small (less than 1/ 10 of the pull-in voltage), which will affect the stability of the circuit and the device operation.   1. Understand the necessary conditions firstly.   1) The power supply voltage of the control circuit can provide the maximum current.  2) Voltage and current in the controlled circuit. 3) The requiring contacts on the controlled circuit. When the relay is selected, the power supply voltage of the general control circuit can be used as the basic factor for selection. The control circuit should provide sufficient working currently for the relay, otherwise, the relay absorption is unstable.   2. After consulting the relevant information to determine the applying conditions, you can find out the type and specification number of the relays required. If you already have a relay on hand, you can check whether it can be used against the data. Finally, consider whether the size is appropriate.   3. Pay attention to the volume of the apparatus. For general electrical appliances, consider the volume of the chassis and the layout of the circuit board installation. For small electrical appliances, such as toys, remote control devices should select ultra-small relay products.     The main test items are briefly described as follows:    (1) Operating value: The voltage required for relay action.    (2) Contact resistance: When electric contact closes, the resistance value between two contacts.   (3) Mechanical life: In the case of the mechanical part without damage, the relay switching times.   (4) Contact voltage: When the electric shock is closed, a certain load current is applied in the electric shock circuit, at this time, the voltage value between the contacts.    (5) Electric life: When the rated voltage is applied on both ends of the relay drive coil and the rated resistive load is applied in the contact circuit, the reliable operation times of the relay under the condition of duty cycle 1:4 less than 300 cycles per hour.    (6) Overload capacity: When the rated voltage is applied on both ends of the relay drive coil and 1.5 times rated load is applied in the contact circuit, the reliable operation times of the relay under the condition of (10 ±1) times/ minute (operation frequency). V. Influencing Factors of Relay Reliability   1.The influence of environment on relay reliability: the average fault interval time of relay working in GB and SF is the highest, reaching 820000h, while in the NU environment, it is only 60000h.   2.The effect of quality grade on relay reliability: the average failure interval of the A1 relay is 3660000h, while that of the C class relay is 110000, the difference between them is 33 times. It can be seen that the quality level of the relay has a great impact on its reliable performance.   3.The effect of the contact form on the reliability of relay: the contact form of the relay will also affect its reliability. The reliability of the single-throw relay is higher than that of the double-throw relay with the same number of tools, and the reliability decreases gradually with the increase of tool number, in addition, the reliability of a single-throw relay is higher than that of the double-throw relay with the same number of cutters. The average failure interval of a single-pole, single-throw relay is 5.5 times that of a four-pole double-throw relay.   4.The influence of structures on relay reliability: there are 24 types of relay structures, and all of them have an influence on the reliability of the relay.   5.Effect of temperature on the reliability of relay: the operating temperature range of the relay is between -25℃ and 70℃. With the increase of temperature, the average time between failures of the relay gradually decreases.   6.The effect of operating rate on relay reliability: with the increase of relay operating rate, the average fault interval time decreases exponentially. Therefore, if the designed circuit requires the relay to operate at a very high speed, it is necessary to carefully detect the relay in order to replace it in time for circuit maintenance.   7.The effect of the current ratio on the reliability of the relay: the so-called current ratio is the ratio of the operating load current of the relay to the rated load current. The current ratio has a great influence on the reliability of the relay, especially when the current ratio is greater than 0.1, the average fault interval time is rapidly reduced, and the current ratio is less than 0.1, the average fault interval time is basically unchanged, therefore, the load with a larger current rating is selected to reduce the current ratio when the circuit is designed because this ensures that the relay and even the entire circuit are not reduced in reliability due to the fluctuation of the operating current. VI. Maintenance of Common Faults of Relay   a. Maintenance of the sensing mechanism For electromagnetic (voltage, current, intermediate) relay, its sensing mechanism is the electromagnetic system. The fault of the electromagnetic system is mainly focused on the coil and the moving and static iron core.   1) coil fault Coil faults are usually caused by coil insulation damage; mechanical injuries form a turn-to-turn short circuit or grounding. Because the power supply voltage is too low, and dynamic, static core contact does not connect tightly, resulting in the current through the coil is too large, the coil heated to burn. The coil should be rewound during the repair. If the armature is not sucked after the coil is electrified, it may be that the wire connection of the coil is removed, so that the coil is short-circuited, therefore, the joint should be re-welded.   2) iron core fault The main fault of the iron core is that the armature can not be absorbed after the power on, which may be caused by the broken coil, having impurities between the moving and static iron core, and the low voltage of the power supply, thus repair should be differentiated. After the power on, the armature noise is big, this may be due to moving or static core contact surface is not smooth, or there is oil on the surface. During repair, the coil should be removed, filing or flattening the contact surface, and oil should be cleaned. Noise may be due to short-circuit or ring fracture, replacing new short-circuit ring to repair. After power loss, if the armature cannot be released immediately, possibly because the moving armature is stuck, the air gap of the iron core is too small, and the spring strain and the contact surface of the iron core have been polluted by oil. Taking maintenance should be differentiated according to the cause of the fault, or adjust the size of the air gap, or replace the springs, or use gasoline cleaning oil.   For the thermal relay, the sensing mechanism is the thermal component, and the common fault is that the thermal component burns out, or operation failures of the thermal element and does not operate.   (1) Thermal component burnout. This may be due to a short circuit on the load side or the high frequency of action of the thermal element. The thermal components should be replaced during maintenance and the setting value should be adjusted again. (2) Operation failure of thermal component. This may be due to the setting value is too small, the operation without overload, or the strong impact and vibration influence, make its action mechanism loosening and tripping. (3) No operation of thermal component. This may be due to the setting value is too small to lose the thermal element overload protection function. During maintenance, the setting current should be adjusted according to the overload working current.   b. Inspection and repair of executing parts Most relay actuators are contact systems. Through its "power on" and "power off" to complete a certain control function. Contact system faults generally caused by contact overheating, wear, melting soldering, and so on. The main reasons for contact overheating are insufficient capacity, insufficient contact pressure, surface oxidation or uncleanliness, etc. The main cause of wear is that the contact capacity is too small, the arc temperature is too high to cause contact metal oxidation, and so on. The main cause of contact melting soldering is that the arc temperature is too high, or the contact is seriously moved, and so on.   The order of maintenance of the contacts is as follows:   1) Open the outer cover and check the contact surface. 2) If the contact surface is oxidized, it is not necessary for the silver contact to be processed, and the oxide layer on the surface of the Cu contact may be lightly scraped with a file or a knife with a knife. 3) If the contact surface is not clean, clean it with gasoline or carbon tetrachloride. 4) If there is a burning trace on the surface of the contact, it is not necessary to repair the silver contact, and the copper contact should be repaired by a file or with a knife. Sand cloth or sandpaper is not allowed to be used for refurbishment, to avoid poor contact due to the residual stand. 5) Contact should be replaced if it welded. If the contact capacity is too small, replace the relay with a larger capacity. 6) If the contact pressure is insufficient, adjust the spring or replace the spring to increase the pressure, if the pressure is insufficient, the contact should be replaced.   c. Maintenance of intermediate part   1) In that air-type time relay, the intermediate part is mainly an airbag. The common faults are time delays. This may be because the airbag is not tight or air-leak, the action delay is shortened, and even the delay is not delayed; it is also possible that the air passage of the airbag is blocked so that the action delay is prolonged. In terms of repair, the former shall reassemble or replace the new airbag, and the latter should open the air chamber and remove the blockage. 2) For the speed relay, its rubberwood pendulum belongs to the intermediate part. If the motor can not stop braking during reverse braking, it is possible that the tilting rod of rubberwood is broken, and it should be replaced when overhauled.     VII. Example Explanation: Delay Relays RF Cafe has said "Relays are a topic that never goes out of date even with the advent of fully solid state relays that use semiconductors in the conduction path,there are still many applications that only mechanical contacts can satisfy." in April 1967 electornics world. It is true that there are switching diode arrays that can handle very high powers,but they are typically expensive compare with relays. Today, let's talk about something about time-delay relays.     What is time delay relays? Time delay relays are simply control relays with a time delay built in. Their purpose is to control an event based on time. The difference between relays and time delay relays is when the output contacts open & close: on a control relay, it happens when voltage is applied and removed from the coil; on time delay relays, the contacts can open or close before or after some time delay. Time delay relays have an important influence in industrial contor logic circuits. There are some examples following:   Flashing light control (time on, time off): two time-delay relays are used in conjunction with one another to provide a constant-frequency on/off pulsing of contacts for sending intermittent power to a lamp. Motor soft-start delay control: Instead of starting large electric motors by switching full power from a dead stop condition, reduced voltage can be switched for a “softer” start and less inrush current. After a prescribed time delay (provided by a time-delay relay), full power is applied. Furnace safety purge control: Before a combustion-type furnace can be safely lit, the air fan must be run for a specified amount of time to “purge” the furnace chamber of any potentially flammable or explosive vapors. A time-delay relay provides the furnace control logic with this necessary time element.   How does time delay relay work? Time delay relays can provide simple, reliable, and economical control. Adjusting the delay time is often as simple as turning a knob. Providing time-delayed switching to start a motor, control a load, or affect a process, TDRs are typically used in industrial applications and OEM equipment. Additionally, they play an important role for targeted logic needs, such as in a small panel or in sub-panels. They have a variety of features and operating characteristics, such as compactness, economy, simplicity, and ease-of-use.Time delay relays not only can be available as plug-in devices but aslo as single-function,single-time-range devices traditionally.   All in all, with an on-delay timer, timing begins when voltage is applied. When the time has expired, the contacts close — and remain closed until voltage is removed from the coil.   Time delay relays circuit and working     See the above circuit diagram, time delay relay circuit contains an electromechanical relay and driver circuit, this circuit decides the time delay to give power supply to the electromechanical relay coil by the way to the load connected to the relay.   This circuit is divided into two sections. The first section is time delay elements such as voltage divider resistor series and two electrolytic capacitors. The second section is a relay with an indicator LED. Resistor R1, potentiometer, and R2 connected in series and across to the DC input supply, the output of the variable resistor (potentiometer) is connected to the C1 capacitor and reverse-biased Zener diode then C2 capacitor finally to the base of transistor SL100. 12V Relay is connected with the collector terminal of SL100 transistor and Bicolor LED terminal green is connected with the emitter of Q1 and terminal Red is connected across collector.   When the supply given to this circuit depends on the value of the Potentiometer small level voltage passed to C1 and it gets charged when its completed and above the cutoff limit of the Zener diode, Voltage passed to the C2 capacitor and it gets charge, finally the base-emitter voltage limit of Q1 transistor reached by the C2 then Q1 gets turn ON and Relay coil gets complete DC supply then Relay energized for to complete the above process it takes some time delay depends on Potentiometer value, C1-C2 charge time and Zener diode breakdown voltage hence we can achieve few seconds to few minutes time delay.   By changing the Potentiometer value or C1-C2 value we can achieve different time delay levels. We can use this circuit to turn ON or turn OFF some sensitive time delay required electrical applications.     How to select a delay relay? Selecting a relay, there are many factors that need to consider including data on thermal,motor-driven, pneumatic, RC, slugged, hydraulic, escapement, and solid-state types.   The fantastic growth of the field of automatic industrial control has increased the demand for new and more versatile devices to perform the basic electrical switching functions required. The use of time-delay relays has grown rapidly to keep pace with the demand for the basic function which they can perform: that of obtaining a predetermined delay from one switch operation to another.     (A) Delay on energization. (B) Delay on de-energization. Time-delay relays perform in a manner quite similar to a standard relay in that they have contacts that open and close when power is applied and removed from the input terminals. The basic difference is that a delay is incorporated into the contact opening or dosing. Time-delay relays are used in a wide range of applications: from determining how full your coffee cup will be when you put a dime in a vending machine, to shutting off the cutting oil on a milling machine. The most popular time-delay relay is the delay on operation, or de-energization, in which the normally open load switching contacts transfer at a predetermined time after power is applied to the input. The contacts drop out immediately upon the removal of the input power   Often a time delay on release, or de-energization, is required. In this case, the normally open load switching contacts operate immediately when the input power is applied and remain in this position as long as the input power remains "on". Upon removal of this power the timing begins, and after a predetermined delay, the contacts drop out. Several variations on these two basic timing modes are used, such as interval "on", automatic recycle, combined "on" and "off" timers, and sequence timers. Many of these can be made by simple connections of the two basic types.   FAQ   1. What is Relay and its uses? Relays are switches that open and close circuits electromechanically or electronically. Relays control one electrical circuit by opening and closing contacts in another circuit. ... In addition, relays are also widely used to switch starting coils, heating elements, pilot lights and audible alarms.   2. What is the relay device? Relay is an asynchronous, screen-free walkie talkie system that allows parents to stay in touch with their kids at the push of a button. Relay is a Republic Wireless product, and makes use of the carrier's cell phone network (via T-Mobile and Sprint).    3. What is Relay and its types? Relays are electrically operated switches. They are used to control a circuit by a separate low-power signal or to control several circuits with one signal. ... The three main types of relays are electromechanical, solid-state, and reed. This overload protection relay reacts to overheating.   4. What is the working principle of relay? Relay works on the principle of electromagnetic induction. When the electromagnet is applied with some current it induces a magnetic field around it. Above image shows working of the relay . A switch is used to apply DC current to the load.   5. Does relay important? Converting a small electrical input into a high-current output is no easy feat, but this task is necessary to efficiently operate a wide range of standard appliances and vehicles. Many circuits achieve these conversions through the use of relays, which are indispensable in all kinds of electronic equipment.   6. What are the 5 applications of relay? Applications of Relays in Electronic Circuits: Relay Drive by Means of a Transistor. Relay Drive by Means of SCR. Relay Drive from External Contacts. LED Series and Parallel Connections. Electronic Circuit Drive by Means of a Relay. Power Source Circuit. PC Board Design Considerations. 7. What is difference between relay and circuit breaker? The Relay is a switching and sensing device, but the Circuit breaker is an isolating or disconnecting device. Relays operate on low power input voltage. ... The Relay is used to control or select one among many circuits, whereas Circuit Breaker is one per circuit. Relay acts an electrical amplifier for discrete signal.   8. How fast can a relay switch? 5 to 15 ms. While the mechanical construction of electromechanical relays allows for much flexibility in switching capability, they have one important limitation: speed. When compared to other relays, electromechanical relays are relatively slow devices -- typical models can switch and settle in 5 to 15 ms.   9. Why do I need a relay for LED lights? Relays can be used to switch a low-current trigger to high current, switch a circuit on or off, reverse polarity, and much more. When adding LED lights, such as off-road light bars, driving/work lights, or other auxiliary lights to a vehicle, you must add a circuit to power the light adequately.   10. What is the major application of relays in our daily lives? The typical applications of electromechanical relays include motor control, automotive applications such as an electrical fuel pump, industrial applications where control of high voltages and currents is intended, controlling large power loads, and so on.   You May Also Like: Making a Arduino Variable Timer Relay How to Drive Thermostat by Using Solid State Relay Product Recommendation: CMRD6055 CB-1001B-70 G6K-2F-Y-TR DC24

The global lamp market has undergone tremedous changes over the last several years. Even government regulation,declining packaged LED and other component prices, and technological advancements have all played a major role in the continued penetration of LED into the overall market. Obvioulsy, LED lamps are the future of lighting, and there is a new invention using LEDs has been pushing out that Osram,a lighting company that offers innovative and sustainable lighting solutions, has revealed that he will stitch LEDs into workwear.  About this amazing news,Osram has taken a first step toward weaving smart lighting into clothes, announcing workwear that lights up with LEDs, while strongly hinting that interactive apparel is coming including a cycling jacket that illuminates when you hit the brakes, and lights that flash when your pulse rate rises too high. At the same time,Osram decided to stitching LEDs into safety vests and work jackets,and choosing Fvrth,a Germany-based safety and sportswear company uvex to operate with.Osram's first stab at textile illumination stops short of interactivity. It simply focuses on giving visibility to workers on job sites. “The textile illumination is incorporated into the safety clothing and ensures greater visibility and hence safety in day-to-day work, for example, on construction sites or in road traffic,” Osram said. “The key advantage of the new technology: Reflector strips on conventional work clothing only reflect incident light, while the light modules ensure active illumination at all times, thus improving safety when working in the dark or in poor visibility conditions.” Osram has been testing the technology for some time.The company used it to help illuminate ice hockey players, sticks, and pucks in an outdoor night game nearly10,000 ft high in the German Alps last year, for example. With sportswear as part of the mix, Osram plans to eventually add sensors that will enable integrated LEDs to respond to physical stimuli, providing health alerts, safety measures, and more.“This will in the future allow various applications to be controlled using an app,” Osram said. “Possible examples include sports clothing that warns the wearer about a high pulse rate via the light guides, or a cycling jacket with an integrated brake light.” Like many lighting companies, Osram is trying to establish LED lights and luminaires as nodes and backbones of information technology networks.While some industry observers expect that one day, OLED technology will prevail for integrated textile illumination, Osram has chosen instead to stitch LEDs, as have other illuminated clothing providers. OLED (organic light-emitting diode) is a patch of material that emits light in response to a current, whereas LEDs are single light points. Osram told LEDs Magazine that it has no plans to use OLEDs for lighting textiles. 

This article introduces stepper motor at full length.There are five parts of this article--the definition of stepper motor; types of steppers; how a stepper motor work; how to select and the basic wiring.  CatalogI. What is a Stepper Motor?II. Types of Stepper MotorsIII. How Does a Stepper Motor WorkIV. How to Select a Stepper motorV. Basic Wiring of Stepper MotorFAQI. What is a Stepper Motor? A Stepper Motor or a step motor is a brushless, synchronous motor which divides a full rotation into a number of steps. Unlike a brushless DC motor which rotates continuously when a fixed DC voltage is applied to it, a step motor rotates in discrete step angles. The Stepper Motors therefore are manufactured with steps per revolution of 12, 24, 72, 144, 180, and 200, resulting in stepping angles of 30, 15, 5, 2.5, 2, and 1.8 degrees per step. The stepper motor can be controlled with or without feedback.   II. Types of Stepper MotorThere are a wide variety of stepper types, some of which require very specialized drivers. By construction the step motors come into three broad classes: 1.Permanent Magnet StepperPermanent magnet motors tend to "cog" as you twist the rotor with your fingers, while variable reluctance motors almost spin freely (although they may cog slightly because of residual magnetization in the rotor). You can also distinguish between the two varieties with an ohmmeter. Variable reluctance motors usually have three (sometimes four) windings, with a common return, while permanent magnet motors usually have two independent windings, with or without center taps. Center-tapped windings are used in unipolar permanent magnet motors. 2.Variable Reluctance StepperJust as resistance determines the flow of electric current, reluctance determines the flow of magnetic flux. In a variable reluctance (VR) stepper, the rotor turns at a specific angle to minimize the reluctance between opposite windings in the stator. The primary advantage of VR steppers is that they have an excellent angular resolution. The primary disadvantage is low torque. 3. Hybrid Step MotorHybrid stepper motors provide excellent performance in areas of torque, speed, and step resolution. This type of motor provides a combination of the best features available on both the PM and VR types of stepper motors. Permanent magnet and hybrid stepper motors are two types of the most commonly used stepper motors. Permanent magnet and hybrid stepper motors are two types of the most commonly used stepper motors. III. How Does a Stepper Motor Work Stepper motors consist of a permanent magnetic rotating shaft, called the rotor, and electromagnets on the stationary portion that surrounds the motor called the stator. Figure above illustrates one complete rotation of a stepper motor. At position 1, we can see that the rotor is beginning at the upper electromagnet, which is currently active (has voltage applied to it). To move the rotor clockwise (CW), the upper electromagnet is deactivated and the right electromagnet is activated, causing the rotor to move 90 degrees CW, aligning itself with the active magnet. This process is repeated in the same manner at the south and west electromagnets until we once again reach the starting position.  In the above example, we used a motor with a resolution of 90 degrees for demonstration purposes. In reality, this would not be a very practical motor for most applications. The average stepper motor's resolution -- the number of degrees rotated per pulse -- is much higher than this. For example, a motor with a resolution of 5 degrees would move its rotor 5 degrees per step, thereby requiring 72 pulses (steps) to complete a full 360-degree rotation. You may double the resolution of some motors by a process known as "half-stepping". Instead of switching the next electromagnet in the rotation on one at a time, with half-stepping you turn on both electromagnets, causing an equal attraction between, thereby doubling the resolution. As you can see in Figure 2, in the first position only the upper electromagnet is active, and the rotor is drawn completely to it. In position 2, both the top and right electromagnets are active, causing the rotor to position itself between the two active poles. Finally, in position 3, the top magnet is deactivated and the rotor is drawn all the way right. This process can then be repeated for the entire rotation.  IV. How to Select a Stepper Motor Selecting between a servo motor and a stepper motor can be quite a challenge involving the balancing of several design factors. Cost considerations, torque, speed, acceleration, and drive circuitry all play a role in selecting the best motor for your application.  At first, we need to know the basic differences between stepper and servo motors.   Stepper and servo motors differ in two key ways, in their basic construction and how they are controlled.  Stepper motors have a large number of poles, magnetic pairs of north and south poles generated either by a permanent magnet or an electric current, typically 50 to 100 poles. In comparison, servo motors have very few poles, often 4 to 12 in total. Each pole offers a natural stopping point for the motor shaft.  Driving a stepper motor to a precise position is much simpler than driving a servo motor. With a stepper motor, a single drive pulse will move the motor shaft one step, from one pole to the next. Since the step size of a given motor is fixed at a certain amount of rotation, moving to a precise position is simply a matter of sending the right number of pulses. In contrast servo motors read the difference between the current encoder position and the position they were commanded to and just the current required to move to the correct position.The greater number of poles allows a stepper motor to move accurately and precisely between each pole and allows a stepper to be operated without any position feedback for many applications. Servo motors often require a position encoder to keep track of the position of the motor shaft, especially if precise movements are required. Note that with today's digital electronics, stepper motors are much easier to control than servo motors. All in all, Selecting the best motor for your application depends on a few key design criteria for your system including cost, positional accuracy requirements, torque requirements, drive power availability, and acceleration requirements. Overall, servo motors are best for high speed, high torque applications while stepper motors are better suited for lower acceleration, high holding torque applications. V. Basic Wiring of Stepper Motor  Stepper motors are available in two basic wiring configurations, bipolar and unipolar. Unipolar motors have one winding with a center tap for each phase. This allows the motor direction to be reversed easily by changing which section of the phase is powered rather than reversing the flow of current. This allows the control circuitry to be very simple. Unipolar motors typically have six leads, three for each phase, but can also be found with five leads, with the center tap of both phases internally connected. Unipolar motors can be easily controlled with a microcontroller or stepper motor controller and are very affordable.  Bipolar motors have one or two windings without a center tap for each phase. In order for the direction of rotation to be reversed on a bipolar motor, the current direction needs to be reversed. This requirement makes the driving circuitry more complicated and is generally implemented with an H-bridge control arrangement or an H-bridge motor driver. While more complicated to drive, bipolar motors are much stronger for the same weight and size. Bipolar motors can be configured with series or parallel windings, allowing them to be driven with the lower current in series or higher inductance and greater torque in parallel. Bipolar motors generally have four or eight leads, two or four per phase, allowing them to be distinguished from the five and six-lead unipolar motors. FAQ 1. What is a stepper motor used for?The stepper motor is used for precise positioning with a motor, such as hard disk drives, robotics, antennas, telescopes, and some toys. Stepper motors cannot run at high speeds, but have a high holding torque. 2. What is a stepper motor and how does it work?Stepper motors are DC motors that move in discrete steps. They have multiple coils that are organized in groups called "phases". By energizing each phase in sequence, the motor will rotate, one step at a time. With a computer controlled stepping you can achieve very precise positioning and/or speed control. 3. What is the working principle of stepper motor?The basic working principle of the stepper motor is the following: By energizing one or more of the stator phases, a magnetic field is generated by the current flowing in the coil and the rotor aligns with this field. 4. Are stepper motors AC or DC?Stepper motors are DC motors that move in discrete steps. They have multiple coils that are organized in groups called "phases". By energizing each phase in sequence, the motor will rotate, one step at a time. With a computer controlled stepping you can achieve very precise positioning and/or speed control. 5. How long do stepper motors last?4.8 yearsThe typical lifetime for a stepper motor is 10,000 operating hours. This approximates to 4.8 years; given the stepper motor operates one eight-hour shift per day. The lifetime of a stepper motor may vary in regards to user application and how rigorous the stepper motor is run. 6. Do stepper motors need drivers?Stepper motors require a driver. There are usually 200 steps per revolution or 1.8 degrees per step (but they also can be “micro-stepped”). In general, you use an H-driver to reverse a DC motor, but it can also be done with a DPDT relay. 7. Do stepper motors go bad?Stepper motors very rarely go bad. It's possible, like a bearing fails. More often the wiring goes bad, or the stepper driver, or the driver overheats. 8. Why is it called stepper motor?Stepper motors are so named because each pulse of electricity turns the motor one step. Stepper motors are controlled by a driver, which sends the pulses into the motor causing it to turn. 9. What are the three types of stepper motor?There are three main types of stepper motors:Permanent Magnet Stepper. Variable Reluctance Stepper.Hybrid Syncronous Stepper. 10. How is stepper motor different from DC motor?The stepper motor operates in open loop whereas Direct current motor operates in closed loop. Stepper are are easy to control with the help of microprocessors and other controlling devices. Control of DC motor is not easy. ... DC motor has a continuous displacement and can be controlled accurately and positioned exactly.  11. Do stepper motors have brushes?Stepper motors are different from ordinary DC motors in at least four important ways. The first difference you notice is that they have no brushes or commutator (the parts of a DC motor that reverse the electrical current and keep the rotor—the rotating part of a motor—constantly turning in the same direction). 12. What voltage is a stepper motor?Stepper motors have a rated voltage and current. A typical stepper motor like our NEMA 17 might have a rated voltage of 2.8 Volts and a maximum current of 1.68 Amps. This basically means if you hook it up to 2.8 Volts it will draw 1.68 Amps. 13. Why do stepper motors fail?One of the major problems with a stepper motor is complete motor failure. This problem is caused by excessive current being sent to the device by the power supply. A short circuit in the wiring from the power supply to the motor cause this problem with the stepper motor. Some application will cause this short circuit. 14. Can stepper motors run continuously?Stepper motors fall somewhere in between a regular DC motor and a servo motor. They have the advantage that they can be positioned accurately, moved forward or backwards one 'step' at a time, but they can also rotate continuously. 15. How do I choose a stepper motor driver?A simple way to choose a stepper drive is to look for four things — voltage, current, microstepping, and maximum step pulse rate. Ensure that the drive can handle a wide range of current so that you can test the system at different voltage levels to fit your application.  

As the development of socialty and technology,wearables are becoming an essential part of the tech world.They not only measure all manner of vital data,but alsw are somewhat of a styly trend.Because of the big need of wearables, A new chemical sensor designed for particularly hazardous applications -- "Smart ring" has been invented. This "smart ring" can detect invisible threats to the wearer, scanning for explosives and nerve-agents that may be present in vapour or liquid form. The technology is designed to be affordable and portable, to provide rapid alerts of any possible security threats nearby. According to IDC, 24.7 million devices were purchased in the first quarter of this year alone, with Fitbit and smartwatches, etc. accounting for the lion’s share of sales,these data have clearly explained that the wearables market is worth billions. These cool, colorful wristbands and watches measure your heart rate and blood pressure, count the number of steps you take and can even stop you from snoring. Specialist wearable devices which can alert you to chemical or biological threats in the environment are considerably less lucrative.Currently, wearables come in a number of non-invasive forms, from wristbands and headbands to tattoos. However, equipping such devices with advanced sensors would be a costly process, making them difficult to produce, the researchers explain. By putting the sensors in a ring, however, they say they’ve managed to create a device that’s both wearable and affordable. The ring can perform voltammetry and chronoamperometric analyses, and uses interchangeable screen-printed sensing electrodes that can quickly detect different chemicals. What's more,that could all be about to change as demand is steadily growing. In order to be successful though, the sensors will have to be compact, non-invasive and affordable. Researchers at the University of California, San Diego, have therefore integrated their “chemical alarm” into a ring which sits neatly and fashionably on your finger. The 3D-printed housing contains an electrochemical sensor cap and the electronics for the data processing and wireless communication to a smartphone or laptop.  Use "Smart ring" to measure electric currents The ring can perform voltammetry and chronoamperometric analyses. The first is an electroanalytical method for the qualitative and quantitative analysis of the chemical composition of substances using current-potential curves. Chemical components lead to a sudden rise in current in the event of voltage which is typical for them. In chronoamperometry, however, chemical substances are identified using characteristic current-time curves. Together, both processes cover a broad spectrum of chemical threats. Researchers have already tested the prototype with explosive mixtures and neurotoxic substances both in gaseous and liquid form, and the ring reacted very sensitively and selectively. Applications could be relatively easily expanded in the future to include dangerous environmental conditions of all kinds. In addition to individuals who work in safety and security sensitive environments, the police and the military as well as airport and train station staff could, in particular, benefit from using the sensor ring.  "Smart" ring's Function: The ring contains an electrochemical sensor cap and a small circuit boardCan detect chemical and biological threats, send data to a smartphone or laptopThe researchers say it can provide rapid alerts of possible security threats This could include explosive material or nerve-agents in vapour or liquid form  

This is a good day because kynix will share an interesting project with you -- Luminous Halloween Costume !  Halloween is coming soon and I know at least that some of you are still procrastinationg you costume build. That's ok,I would share a fun and easy luminous Halloween costume that takes almost no time to buildstill impresses the pants off your friendsis appropriate for all ages So at first,we should prepare some components as follow: Knit Hat in Red, Green, Blue or White,etcBlack T-shirtElectrical TapeHot Glue Gun and GlueSoldering IronSolderQduino Mini Dev BoardWS2812 LED StripLiPo Battery Next,let's start to make it. The first step,I made the shirt which will represent the anode and cathode of the LED.Ake the electrical tape and cut it into two pieces. One should be about 2 inches shorter than your shirt, and the other about 4 inches shorter. On each piece cut one edge into a point. Then place them on the shirt parallel to each other, pointing downward from the collar. Set this aside. The second step, place the hat on whoever will be wearing the costume — or someone with a head similar in size. Fold up the bottom to make a small lip. Starting in the back, hot glue the LED strip to the hat, wrapping it around the hat from the bottom and moving up. Cut the LED strip when there is about 1 to 2 inches of hat left at the top. Next,take the hat off and count the number of LEDs on it. After that,we need to use the program provided below to program Qduino.You will need to make two small edits. First, update numPix variable to the number of LEDs on your hat. Then find the four colorWipe commands in the loop function. You will notice that I have included red, green, blue and white. Comment out the lines that are not the same color as your hat. If you have not already, you will need to install Adafruit’s Neopixel Library and the Qduino board into your board manager in Arduino. For more instructions on how to do this, please visit this Qduino Hookup Guide and our Arduino Library Installation tutorial. Upload your program using the code below://Melissa Felderman for SparkFun Electronics. Functions have been taken from the adafruit neopixel library example code.  #include <Adafruit_NeoPixel.h> #define PIN 2 int numPix=150; Adafruit_NeoPixel strip = Adafruit_NeoPixel(numPix, PIN, NEO_GRB + NEO_KHZ800); void setup() { strip.begin();  strip.show(); // Initialize all pixels to 'off'} void loop() {  // comment out all lines except the color you want on your hat.  colorWipe(strip.Color(255, 0, 0), 50); // Red  colorWipe(strip.Color(0, 255, 0), 50); // Green  colorWipe(strip.Color(0, 0, 255), 50); // Blue  colorWipe(strip.Color(0, 0, 0), 50); // White } // Fill the dots one after the other with a colorvoid colorWipe(uint32_t c, uint8_t wait) {  for(uint16_t i=0; i<strip.numPixels(); i++) {    strip.setPixelColor(i, c);    strip.show();    delay(wait);  }} Finally,Solder the LED strip’s leads to the Qduino. The DIN lead should go to D2 on the Qduino, VCC to VCC, and GND to GND. Pop in a LiPo battery to your Qduino and turn on to test.  Put on the black shirt and then the hat. Fold the bottom edge over again to make a lip. Hide the Qduino and LiPo inside, and then turn it on. Now you are a luminous human!