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Questions tagged [triac]

A TRIAC is a component often used to control high power currents, both as a switch and as a "dimmer"-like construction for controlling lamps or electric engines.

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Triac switch cause of heating

As a newbie to hardware design, I'm having some trouble picking components. I want to switch a 24V AC Solenoid valve using a triac. According to my research/experience, transistors heat up during use. ...
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34 views

How to connect power phototriac's gate pin?

I have inherited a design that uses a power phototriac (basically an optotriac with a built-in TRIAC) -- the VO2223B -- that includes a pin to access the power TRIAC's gate (pin 5 below). The ...
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1answer
35 views

Questions regarding eliminating hysteresis in ac dimmer

In the following circuit it says: “This hysteresis effect can be eliminated however, using the circuit from a detailed application note from Littelfuse shown in Fig. 6.4.4. Here the capacitor C1 is ...
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47 views

Driving Triac With MOC3021 for 12 v ac

i am using triac bt136 with moc3021 to drive 12vac but i found the problem is it possible to drive the triac on 12vac i made the circuit as shown in link on 12 vac but i didn't get any exact sine ...
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Use a TRIAC to connect/disconnect a capacitor to a PSC motor

In the image above, we see a PSC motor, with its 3 terminals, connected to a control board. This board has a RUN capacitor always connected to the motor. When the motor has to turn, the board applies ...
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53 views

BT136 TRIAC not closing on LOW signal to the MOC3021

I am trying to make an AC dimmer. I am following this schematics for my circuit, Circuit Link as you can see in the below picture that I am able to turn the signal on after a short while of zero ...
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37 views

Can't get my led bulb to turn on using triac and optocoupler

I have made the below circuit but my LED bulb won't turn on, although circuit works fine if replace the led bulb with a small led and ac supply with 5v dc supply. Can someone guide me in a right ...
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48 views

Problem with TRIAC simulation

I am trying to simulate a triac with MOC3020 but the MOC3020 does not output to drive the gate. The schematics is shown below: The waveform follows: Waveform with updated duty cycle to allow LED to ...
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64 views

Light dimmer circuit using triac gives fluctuating dimming

Light dimming using triac and optocoupler is very common and basic circuit, I have successfully tested the dimming for 1 channel (1 triac, 1 opto-coupler) now I want to add one more light dimmer with ...
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1answer
124 views

SSRs influenced by physical proximity?

This is part of a two-head EVSE. The two solid-state relays are used to drive contactors that supply high current power to the vehicles. I used to use a MOC3040 based triac circuit for this job, but ...
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65 views

Help for voltage is being passed trough load, even triac is OFF condition

We are using below circuit for home automation. We are facing problem when 5v battery is not passing to the circuit,but even 1 volt is being passed trough load, even triac is OFF condition.. Please ...
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BTA16 triac snubber and operation quadrant

I am working on a dimming circuit to be operated by an ESP8266. I have read a lot on this over internet and got a working circuit as well. But myself I am not satisfied with my understanding of ...
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61 views

Mains AC overvoltage protection using a TRIAC

I am trying to design a circuit that protects 127V appliances if plugged in a 220V socket (in Brazil 127 and 220V sockets have the same shape and it's easy to plug a 127V appliances in a 220V socket ...
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61 views

Best TRIAC for zero cross detection

I already asked this question Triac BT 136 getting shorted when load is given to T1. When I referred this link, I understood rate effect is the root cause for our problem. To avoid this either we ...
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102 views

Triac BT 136 getting shorted when load is given to T1

We have a optocoupler switching circuit which triggers the TRIAC with ZCD. Everything is working fine with all inputs. Connection is T2 as a input T1 as output Gate as Trigger from Optocoupler As ...
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71 views

TRIAC and Driver is heating up

I am trying to do a dimmer and below is my schematic. Before doing an actual PCB, I did a proto on a veroboard and the circuit works perfectly. Now when I did a PCB and got it back from the ...
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hump on rectified signal and inconsistency on gate signal

Following is the image of my circuit, I am working at the moment. This is not my own circuit but I am trying to understand and work on it. Following is the signal I am getting at Gate2. What could ...
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How to safely switch a big inductive load with a Triac using a capacitor snubber?

I am building a Spot Welder with a big powerful transformer. I have to switch a big inductive load of 70mH (input of a transformer) The switching will be done with an SSR (Opto Triac Zero crossing SSR-...
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188 views

Calculate Angle for Triac Phase Control

Triac-based phase control of the mains power into resistive load. According to this post, https://www.physicsforums.com/threads/how-to-calculate-rms-voltage-from-triac-phase-angle.572668/#post-...
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64 views

Pulse skip modulation vs Phase cutting for AC inductive loads?

What is preferred and safe mode for controlling power to an Inductive AC load when driven by a Triac? I am using a microcontroller with zero crossing optocoupler to drive the control signal and the ...
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57 views

Low current control of triac speed controller?

I'm using a cheap Chinese commercial triac speed controller to control a universal motor that pulls considerable amperage (where "considerable" is no more than 15 amps at 117 volts). I would like to ...
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123 views

What components do I need to add to the power circuit for this ESP8266 project?

I'm planning to make some controllers for each of the electrical heaters in my house. The heaters use a pilot wire to control their mode of operation: I'm following this project to control the pilot ...
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86 views

MOC3021 optocoupler not working ( or not working , a bit confused )

My Understanding As far as my understanding of MOC3021 optocoupler goes, it should latch pins 4 and 6 whenever there's a current flow between pins 1 and 3. The Confusion Image 1 - D1 not glowing ...
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221 views

Can i get away with a pcb heatsink for a triac?

so, i have a bunch of to-220 L4006L5TP triacs laying around and i have to design an AC phase control pcb, reading the datasheet i saw that the Rθ(J-A) is 50°C/W, the Rθ(J-C) is 3.3°C/W and the voltage ...
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193 views

Overvoltage protection circuitry choice

I need to design a input overvoltage protection for a 45W DC-DC converter rated for a 9-24V wall wart input (so, 45W / 9V = 5A input current at max). So far I've seen two approaches (schematics below):...
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113 views

A question about triac output of zero crossing SSR relay

In a zero crossing SSR if the output is a triac, would the gate be fired/triggered every 180° or would the gate be applied a constant voltage all the time? I'm asking because in both cases the load ...
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115 views

How series resistors influence clearance-creepage requirements?

simulate this circuit – Schematic created using CircuitLab I'm designing a circuit which should leak some amount of current from AC line to PE. The question is regarding clearance-creepage ...
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Relays vs. thyristors: What is best for swiching 230 V lights on and off rapidly (~ 5 Hz)?

I am building my own disco/party lights. 230 V/60 W bulbs, and ideally I would like to switch them on and off at 5 Hz. I was planning on a simple setup with an Arduino controlling the lights. My ...
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1answer
107 views

Operating a 24VAC solenoid with a Triac. Protecting with TVS DIODE, RC Snubber or both?

As part of a project I am controlling 24VAC solenoid sprinkler valves like this https://rayshobby.net/wordpress/understanding-24vac-sprinkler-valves/ using a triac (BT1308W) http://www.mouser.com/ds/2/...
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124 views

Overvoltage protection for AC relay dilemma

I am currently designing a safety-related device that has to open a relay when a certain event occurs. During most of its life, this relay will be closed, and only open if the safety event occurs, ...
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720 views

Why does this washing machine have microprocessor pins directly connected to the main AC power?

I'm studying the attached washing machine partial schematic at the point in which the main microcontroller activates 2 water elecrovalves. I would ask: It seems the microcontroller pins 36 and 40 are ...
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3answers
124 views

Triac Dimmer Supplying a Purely Inductive load

I was asked a question in my lab viva today, on a triac switch supplying a fixed value inductor of 0.2 henry. How will the current and voltage of the inductor vary, if the triac's firing angle was ...
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2answers
262 views

Difference between TRIACs holding and Latching current

I am reading wikipedia page of TRIAC. While reading, I got struck with holding and latching current definition. They look ...
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2answers
54 views

How are small triacs able to “switch” or control high power AC loads

I am currently looking ways to control or siwtch a max 220v 35A load. Simple magnetic relay rated for such load would work, but i am exploring the other alternatives too. here i stumbled into triacs, ...
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1answer
158 views

Triggering of TRIAC for Crowbar Protection

I am reading the datasheet of TRIAC (T1235T-8G). I am not sure how to trigger the TRIAC and what do they mean by ...
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1answer
86 views

Potentiometer is Heating [closed]

I have this light dimmer circuit, when I plug it into the AC, the dimmer works fine but I noticed that the heat in potentiometer is increasing, is there any workaround to fix this problem?
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51 views

Driving multiple loads with a single TRIAC and multiple optoisolators

I simulated this circuit in multisim. It is working fine. However, I am just curious to know if it is possible to drive multiple loads with multiple opto-isolators with single TRIAC? Something like ...
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1answer
160 views

TRIAC won't turn on/turn off

I'm trying to make simple lamp switching circuit to work, but it just doesn't want to work as intended - question is, why? I'm using MOC3021 random phase optotriac with BT136/600E sensitive gate ...
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388 views

Triac Equivalent or Substitute

I have a schematic which uses a triac, for example a BT136. Please have a look at the attached schematic (this is a schematic for a soldering station) What parameters from the datasheet we should ...
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1answer
243 views

Arduino PID and AC controlling

I'm trying to make my own PID temperature controller using Arduino. Arduino PID library outputs a PWM signal. I need to control 230VAC using this PWM like a triac phase angle controlling. If I use a ...
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1answer
75 views

My triac turns on when gate attached to vcc (good)… but also when connected to ground (bad)

I'm still really new at working with triacs and understanding them, but I want to make a circuit that allows a microcontroller to turn on/off an AC signal (very low power, not mains, don't worry) to ...
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1answer
188 views

Problem with Solid State Relay based on MOC3061

I was experimenting the circuit below. In the load, I placed the input of a full bridge rectifier. The issue is that the power triac is never activated. Sounds like the zero cross is not working. Is ...
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1answer
138 views

Control 24VAC solenoid with arduino using a octocopuler and a Triac

Following a previous question I implemented the following schematic on my PCB. The schematic : My PCB: I have been unable to make it work, if I measure the voltage on j13 it's allways 25v, i know ...
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1answer
126 views

TRIAC not turning off correctly

I am using this circuit with a BTA16 TRIAC: The load is a 110/12 V transformer. I am getting spikes in the output. Note: CH1 is the secondary of the transformer (load), CH2 is the MOC3021 input. ...
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1answer
38 views

Multiple lights dimming using single TRIAC zero detcetion module

We know well we can dim single lights using single TRIAC module with the help of PWM signals from controller. My question is, I want to control the lights which are placed on hall. Let us consider 15-...
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1answer
119 views

Bridge Rectifier as Load for an SSR Circuit

Somehow, I wanted to control the power to a bridge rectifier. I had two ideas in my mind: 1- Using a PCB mounted power relay driven by a transistor (is isolation maintained?) 2- Using a SSR, i.e, a ...
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74 views

Understanding this TRIAC circuit

I have an inquiry about the circuit below: When a high signal is continuously given to the transistor, it enables the optotriac with zero crossing. The optotriac enables the power triac, and the AC ...
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1answer
268 views

RobotDyn dimmer controlled by ESP 07 only results in flickers

I use a dimmer module connected to an ESP07 which has Node MCU firmware. I'm using the Z-C interrupt to skip sinusoidal pulses, however I only obtain flickering instead of dimming. The light is bulb ...
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1answer
408 views

Driving a 24VAC solenoid with arduino using a octocopuler and a triac

Following a previous question I have redesigned my schematic: I'm trying to energize a solenoid used to open and close a 24VAC sprinkler valve I have the following questions : 1) The GPIO leg can ...
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73 views

Would it be a good idea to use a TRIAC as a crowbar in this application?

The idea here is to sense when the electrodes of the transformers secondary make contact which would be sensed by the optocoupler and trigger the SCRs to switch ON the transformer for spot welding. ...