The k3021p is a 1channel 6pin nonzero crossing phototriac output optocoupler consists of a phototriac optically coupled to a gallium arsenide infraredemitting diode. The opto coupler may not have sufficient ctr current transfer ratio to drive the relay coil. Would it make sense then to use the optocoupler or a diode would suffice since i would not be able to achieve circuit isolation with the former anyway. I have varied the r1 and r2 values from 100 ohms up to 10 kohms and varied the input v1 from 0 to 10 v but the output either remains at some constant value in the mv or it is equal to v2. Optocoupler tutorial about how optocouplers and optoisolators use light to. You can keep improving your circuit, like adding an optocoupler, and play with the circuit to turnonoff the relay using a high or low digital signal from.
K3021p optoisolator triac output 5300vrms 1 channel 6dip from vishay semiconductor opto division. I am using a microcntroller to drive the optocoupler which in turn drives the gate of the triac. The coil of the relay needs a large current around 150ma to drive the relay, which an arduino cannot provide. As shown in the following circuit diagram, the relay driver may consist a npn transistor or a pnp transistor. Since the output is driven by a triac we can drive loads upto 400v and the triac can conduct in both directions hence controlling ac loads will not be a problem. Hi everyone, actually i have made a simple optocoupler moc3021 driven triac for lamp on off. K3021p vishay semiconductor opto division isolators. This time delay relay circuit can be used to time delay for the load, to be connected to the relay output to run after a specified time.
The following post describes how to drive a relay by using an isolated method, or through an optocoupler device. The driven relay can then operate as a switch in the circuit which can open or close, according to the needs of the circuit and its operation. The wellestablished relaydriving circuit uses an optocoupler to isolate the grounds and noise coupling between the lowvoltage digitalcontrol signal circuit. Relays are one of the most important components in electronic circuits. It can also be connected to ground with an external resistor for a higher degree of control over switching sensitivity. Why are relays so frequently driven by optocouplers. A better device is the fairchild cny17f4 that has a ctr range of 160. In this article we will comprehensively study a transistor relay driver circuit and learn how to design its configuration by calculating the parameters through formulas.
As well as the standard common emitter configuration for a relay switch circuit, the relay coil can also be connected to the emitter terminal of the transistor to form an emitter follower circuit. In this project the npn transistor 2n2222 drives the relay when the npn junction gets saturated. The problem is that when i am trying to switch a relay according to the attached circuit, relay doesnt toggle. Technical data pushbutton limit switch sensor optocoupler relay or optocoupler plc motor contactor motor. Optocouplers and optoisolators can be used on their own, or to switch a range of other larger electronic devices such as transistors and triacs providing the required electrical isolation between a lower voltage control signal, for example one from an arduino or microcontroller, and a much higher voltage or mains current output signal. Driving an electromechanical relay from a lowvoltage digital io line is a common situation, but there are.
K3021p vishay datasheet and cad model download octopart. In part 1 we looked at a number of bipolar transistor and mosfet driver circuits. Examplein terms of usage say a person wants to turn on 500 kw motor, he could simply. It can be controlled directly by microcontroller raspberry pi, arduino, 8051, avr, pic, dsp, arm, arm, msp430 ttl logic. Use them in any sector of industry including process technology and power engineering, railway applications and machine engineering, as well as general control cabinet construction. K3020p, k3020pg series optocoupler, phototriac output. Now i am trying to use optocoupler pc817 as a switch in place of transistor. This is a 5v 4channel relay interface module, for controlling various appliances, and other equipments with large current. Here we have used 12v 10amp relay in this pcb board, but you can also use 5v. I am dealing first time with optocouplers so kindly tell my mistakes. But the circuit shown in figure 2 is completely isolated from. The phototransistor can be used to switch current in the output circuit. I have some optocouplers to isolate mcus power and power supply for the relays to control leds, dc and ac drivers.
Whether relay sockets or pluggable relay and optocoupler modules, wagos array of relays and optocouplers offer a solution for any requirement. The input signal is connected directly to the base, while the output is taken from the emitter load as shown. Now a question arises, why do we need the extra bit of circuit to drive the relay. A relay driver circuit is a circuit which can drive, or operate, a relay so that it can function appropriately in a circuit. Optocoupler, phototriac output, nonzero crossing, 400 vdrm.
Here we have used a 12v 10amp relay in this pcb board, you can also use 5v relays. A lot of these seem to use an optocoupler, driver transistor and a relay to drive the load example on amazon. Optocoupler, phototriac output, nonzero crossing, 400 vdrm description the k3020p, k3020pg series consists of a phototriac optically coupled to a gallium arsenide infraredemitting diode in a 6lead plastic dual inline package. Buy vishay, k3021p phototriac output optocoupler, through hole, 6pin dip k3021p. All the relay driver circuits above are the pulse output of the digital circuit to control a transistor works and drive relay as an onoff switch for circuit or external devices next, to using it now selected to suit the circuit. Microcontroller cannot drive relay directly because required current for driving relay is much more then the current supply by microcontroller. Circuit options explore issues, solutions for relay drivers. Figure 14 shows how to interface two ttl circuits, using an optocoupler circuit that provides a noninverting action. Then consider using a latching relay and explore using a pchannel or an nchannel mosfet. And optocoupler will be triggered by the active low signal. The nonzero crossing functionality enables full wave control.
In this 4channel relay driver circuit we have used an optocoupler whic his triggered by active low signal, to trigger the npn transistor which further drives the relay. Optocoupler, phototriac output, nonzero crossing, 400 v. Here we have used 12v 10amp relay in this pcb board, but you can also use 5v relays. Although on measuring voltage with multimeter, it shows 12 v, but doesnt toggle it. Featuring galvanic and electrical noise isolation, the. Diy arduino relay driver shield use arduino for projects. In this 3channel relay driver circuit, we have used an optocoupler to trigger the npn transistor which further drives the relay. This is the same circuit ive seen on other websites describing how to use the 4n25. Note that the optocouplers must have a ctr current transfer ratio greater than 100% or else the circuit cannot latch. K3021p vishay, optocoupler, triac output, dip farnell. They had a flaw of having to be electrically connected to low voltage digital circuits. Relay coil and sensitive logic circuits optimized to switch relays of 12 v rail capable of driving relay coils rated up to 6. Hi in the attached diagram, can the relay be powered the blue ovals from the same source as the pic.
Im wanting to control two 12v relays by means of an npn transistor, and will. Typical relay current driver circuit use an optocoupler connected to a transistor which then drives the relay. Pricing and availability on millions of electronic components from digikey. K3021p vishay, k3021p phototriac output optocoupler. This is my 4th tutorial on how to drive a relay not a relay module with an arduino. Latchingnonlatching relay driver circuit with darlington optocoupler. The circuit shown in figure 1 will drive the relay through optocoupler in same circuit with same power supply. Lets look at an older circuits ive used in the past. It provides isolation between control circuit and power switching and save the control circuit from highvoltage transient or surge voltage usually generated from inductive load like motor, relay etc. The most distinct part of optocoupler as a switch is to isolate low voltage circuit from high voltage circuit. Interfacing optocoupler with arduino engineering projects. In this project, we will show how to connect an optocoupler chip to a circuit. On the relay driver, you do show the clamp diode across the phototransistor it should go across the relay coil. Driving relay directly from optocoupler, what is best.
These simple optocoupler relay driver circuits can be used in variety of electronic projects. The load is switched on and off using the relay s metal contacts that move when the coil is energized. Moc3021 is a zerocrossing triac driven optocoupler or optoisolator. Compare pricing for vishay k3021p across 20 distributors and discover alternative parts, cad models, technical specifications, datasheets, and more on octopart. An overview of transistor driver circuits for use with microcontrollers with sample circuits. Vishay semiconductor opto division has several brands around the world that may alttemate names for k3021p due to regional differences or acquisition. How to connect a relay through an optocoupler homemade.
I have a question about controlling relays by using optocoupler. The question was asked by one of the interested members of this blog, miss vineetha. Relay drivers gate drivers are available at mouser electronics. Introduction of optocouplers types, working and applications. Ti uln2003lv sink driver features 7 low output impedance drivers to support low voltage relay and inductive coil applications. Optoisolated transistor drivers microcontroller interfacing. It is suitable for use with the high current triac driver and switch small ac loads. The 4n37 has a minimum ctr of 100% and maximum of 200%. There are hundreds of tutorial available on how to use a relay module but i could not find a good one that shows how.
The idea is to use a power lamp whose activation requires mains ac. When using logic signals to control a relay, a driver circuit must be used to boost the current needed to energize the relay s electromagnetic coil. The circuit shown below is a typical circuit used for ac load control from microcontroller, one led can be connected in series with moc3021, led to indicate when high is given from micro controller such that we can know that current is flowing in internal led of the optocoupler. It is possible for one not to function if the ctr falls too close to 100%. This interfacing is possible thanks to abbs relays and optocouplers ranges, which offer wide adaptation in both voltage from 5 to 400 v and current from 107 to 16 a as well as high isolation between input and output from 2 to 4 kv. The limitation of this type circuit is due to the collectoremitter breakdown voltage of the optocoupler and the gatesource breakdown voltage vgs on the mosfet. Instead, use it to turn on a driver transistor that has lots of gain like the 2n4401. Here, the optocoupler led and currentlimiting resistor r1 are connected between the 5v positive supply rail and the outputdriving terminal of the ttl device rather than between the ttl output and ground, because ttl outputs.
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