Questions tagged [triac]

A TRIAC is a three-terminal semiconductor component that conducts current in both directions when triggered. It is often used to control high-power AC currents, both as a switch and for "dimmers" for controlling lamps or electric engines.

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LED light bulb is flickering when switched on

I am a Physics Major student and have to do a project in our end sem. Since we read a lot of theory and workings and very less practicals, I am a bit weak in electronics. So here is the problem. Our ...
Mrinmoy Sarkar's user avatar
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MOC3083 + replacing triac with 3Q one + no snubber

This is famous circuit from the MOC308x datasheet which many people use and refer to: I have recently asked related question on the usage of the BT136. I would like to understand how this circuit ...
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MOC3021M + JST16A-600B TRIAC Circuit problem: Resistor blowing up

let me clarify first than I'm no expert in electronics, so, I could be doing something really stupid here. I want to replace the control board of my kitchen extractor motor with a custom version that ...
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Why is this light-dimming configuration flickering? Why is it not stable?

My question is why is this configuration showing an unstable flickering voltage accross the light bulb? Were incorrect capicitance values used? Observing the oscilloscope, I note that there is some ...
Zipho Lunika's user avatar
2 votes
2 answers
167 views

Heater circuit using series resistors

The subject seems to be very easy and simple but performing research and looking at the real devices I get more and more questions. Let's take this article as a basis. It has the following circuit: ...
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Structure of a thyristor

In the test of the thyristor (BT151S-500L) that I removed from the contactor driver (in the multimeter diode test phase), I saw that the gate-cathode voltage drop was 236mV, but the cathode-gate ...
Jundullah's user avatar
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TRIAC Controlled Motor circuit: PWM logic doubt

I'm working on the logic board of my kitchen air extractor. I wanted to "hijack" the controls (physical buttons) to be able to control those with an ESP8266. While I was analyzing the ...
KnF's user avatar
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Fan dimmer using MOC3021 and TRIAC suddenly stopped working. Cannot find possible reason. The circuit worked fine for two days

I am trying to control speed of a fan using MOC3021, BT136 and zero crossing detector. The circuit worked fine for 2 days and then suddenly stopped working. I am unable to find the problem in the ...
Aditi Kumari's user avatar
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Triac flickers when I apply main power

I am building an ESP32-based AC mains power switch by using TRIAC BT136-600D (common triac). My first issue is my load didn't turn off the load (lamp) properly at 30%-40% brightness, and when triac ...
Asif Uz Zaman's user avatar
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Protecting Triac + Relay from surges

I am having 3 triacs and 3 relays that are used to control heater elements in triangle configuration. Atleast the triacs need some kind of surge protection since they can only handle 800V and surges/...
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What is the purpose of diodes on the gate of a silicon bilateral switch (SBS) TRIAC trigger circuit

Here is a typical TRIAC SBS trigger circuit to control a resistive load. This example is from the BS08A datasheet but there are plenty of others. What is the purpose of the D1,D2 and R3? It appears to ...
Teemu Ikonen's user avatar
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What is a bridge rectifier doing in this TRIAC regulator?

Recently I purchased a TRIAC-based mains regulator and took a look inside. It's a very typical TRIAC regulator, except it contains a bridge rectifier (DB207S), the purpose of which is not clear to me ...
Борат Сагдиев's user avatar
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Troubleshooting Vacuum Roller Motor

I am trying to repair a vacuum so that the carpet roller will work again (motor does not run). I have disassembled the head of the vacuum and found what is probably a fairly simple electronics board ...
IronJaguar2276's user avatar
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What is this glass bulb containing three parallel electrodes?

I'm trying to figure out what the glass component on the PCB is. Maybe some sort of vacuum tube? Maybe a triac? It's got three leads, and appears to have three parallel electrodes inside the glass ...
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Can a MOC3032M optocoupler be used to generate a DC PWM signal?

I'm trying to make a circuit that can output an 80 Hz PWM signal. I'm planning to use an Arduino to switch an optocoupler that will control the duty cycle. Here is my circuit: After building the ...
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How on Earth can a solid state relay be constructed?

Relays are very handy components. Relays allow current to both directions on the controlled load circuit so they can be used for both AC and DC. However, relays have a finite lifetime if connected/...
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RCD snubber circuit

I'm designing a timed fan switch using an 800V 25A (overkill) TRIAC with an RCD snubber circuit with 120VAC source. The circuit is shown at the TRIAC shut off at I_hold of 50mA. The load current at ...
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MOC3021 stopped working

I am trying to make a dimmer circuit using an MOC3021 and a BT136. I used a zero crossing detector with a 4N35. The dimming is controlled with a processor. Initially the circuit worked fine, but ...
Aditi Kumari's user avatar
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1 answer
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TRIAC controlled fan output on furnace control board not working

At board power-on, the fan output connector has mains (230V AC) voltage without the fan connected, that drops to ~2V AC with the fan connected. At power-on, on the attached display, the board shows a ...
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Triac dimming light is affected by other non dimmable load

When I am using one dimmable light turning on/off is working OK and dimmable is OK. But when I’m using other non-dimmable load turn on/off, then dimmable light is on/off for the 1 s. Is there any ...
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TRIAC driver circuit - MOC3021

I have created a TRIAC AC dimmer circuit using an MOC3021 and I am facing the problem that the output is always on. Please help me rectify the issue. Please see the image of the circuit and Zero PCB I ...
Rahul Goyal's user avatar
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Schematic of a simple zero-crossing triac switch

I have a triac in a 60Hz 120V power line (as is often done for dimming) and want it to only switch on the power when the AC voltage is low (widely between -40V and +40V would even be fine). This is ...
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Triac Not Triggering in Q3

I tried simulating this circuit in LTSpice, but, if I'm interpreting this correctly, the triac isn't triggering in Q3.The gate current reaches -360mA when I would expect the triac to enter Q3. I'm not ...
user120632's user avatar
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2 answers
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What's the circuitry inside triac driver optocouplers?

When looking through datasheets I can't find a single one that shows the inner circuit of a triac driver optocoupler, all I get is this common diagram: What that zero crossing circuit looks like? how ...
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How to Get Started with Triacs

I'm interested in building a solid state relay module at home using a triac. I know the safety risks associated with this project. I'm also aware of the cheap SSR modules capable of the same things. ...
user120632's user avatar
6 votes
3 answers
321 views

RC snubber causing latch in relay

I'm driving an RT314730 relay directly with an MOC3063: simulate this circuit – Schematic created using CircuitLab The problem is when SW1 is open the relay latches. I tried 10nF instead of ...
ElectronSurf's user avatar
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3 votes
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Is it possible to drive a relay with 220VAC coil without a triac?

Can I drive this relay RT314730 directly with MOC3041M? I want to save some space and money.
ElectronSurf's user avatar
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Power supply board failure: could it have been cause by a misoriented triac?

I have this power supply board from a Honeywell HPA300 air filter that has a burned out triac (BT3) in this row of 4 side by side triacs (...
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Reverse engineering water heater power control board

I am trying to reverse engineer a water heater power control board that I have found in a hot water dispenser. In the original machine, it powers a 2000 W heater (which I will keep) and is connected ...
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Two SCR thyristor modules using gates tied together to trigger

When I tie the gates of a MCC 95-16 together, it conducts AC at decreasing gate milliamps as I raise input voltage. Is this acceptable to power a microwave transformer? My zero crossing opto driver at ...
callmemac's user avatar
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TRIAC and zero cross detection

I am working on an IoT project to control the speed of my ceiling fan through my mobile. The problem is that the TRIAC and the fan speed circuit just won't work when it is on a PCB. I know it sounds ...
De PuP's user avatar
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Controlling multiple TRIACs using one optoisolator

I was wondering if it's possible to control multiple TRIACs using only a single Optoisolator. All the loads are resistive. here is the schematic of what I am trying to achieve. I have tried to do some ...
Mohamed El-Sayed's user avatar
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Circuit Design For HDMI Shut Off

I am building a device that will turn on/off the HDMI to a monitor. This will allow a microcontroller to flip the monitor on and off. I tried a basic design that switches the 5V, DDC/CECGround, and ...
Joel Danowitz's user avatar
2 votes
1 answer
131 views

Switching only one AC side live/netural using Triac/SCR

I was wondering if Triacs/SCRs can be used for switching only one side of AC (neutral or live), or whether there are other component that I can use for this. The load is an AC motor, and the current ...
Mohamed El-Sayed's user avatar
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1 answer
122 views

PWM from the Robodyn AC light dimmer

I am currently conducting a test on a Robodyn AC light dimmer product, and I want to check the PWM trigger output from the controller. Due to equipment limitations, I am only checking the trigger from ...
Angga Amalul Ahli's user avatar
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Controlling TRIAC with PWM from microcontroller

I am looking to control a mains heater with a microcontroller. It seems like most solutions use an optocoupler to signal the microcontroller at a zero crossing and another optocoupler to trigger the ...
Levi Applebaum's user avatar
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0 answers
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Triac Equivalence

I was troubleshooting an infant radiant warmer having little output voltage to the radiator power outlet and I did a continuity test on a triac and it's a dead component. I don't know the equivalence ...
Smart 's user avatar
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3 answers
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Why does my voltage regulator always output maximum voltage? [closed]

I bought a cheap AC-AC voltage regulator from AliExpress (marked as being a 4000w SCR) very similar to the one toredown in this article. As one commenter points out, the output voltage remains at ...
Danny Beckett's user avatar
2 votes
1 answer
137 views

MOC3041 typical SSR circuit, when snubber is applied, triac never turns off

I am trying to make this circuit: I got reference from this site, which is very useful, thanking them for info; https://components101.com/ics/moc3041-zero-cross-triac-driven-optoisolator Despite all ...
Amol Vaidya's user avatar
4 votes
3 answers
1k views

Are heat sinks necessary for a Triac even in low current circuit?

Triacs tend to get hot in circuit when operating. The temperature can be determined with estimated output current. In my understanding, with low current output, a Triac can operate within maximum ...
jjk's user avatar
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1 answer
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How to suppress back-EMF in TRIAC-based AC power control system? I am using an inductive load

I have designed a AC power control using TRIAC, facing issues while driving an inductive load. In the above attached waveform, I have fired at 15% of half cycle (both positive and negative). The issue ...
Pradeep Wagre's user avatar
1 vote
0 answers
183 views

Detailed calculations for DIY SSR (solid state relay) circuit

I just want to understand the calculations for a DIY SSR project. I do know the components required but I don't know how to calculate resistance values for this circuit. Also, what is the output of ...
realprocess's user avatar
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3 answers
56 views

Help with a VCR for Triac dimmer circuit

I’d like to replace the potentiometer component (RV1) of a typical triac dimmer circuit with a voltage controlled resistor. The DC control voltage has a range of probably about 1 mV - 2.5 V. It seems ...
Eli Y's user avatar
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Is this RC Snubber functional?

I had made this circuit which is basically works somehow as a UPS (when there is a power failure from the mains (220 VAC) the inverter line turns on and keeps the load on) and yes I had tested the ...
Hazardous Voltage's user avatar
1 vote
1 answer
114 views

How to drive TRIAC from MCU with supply referenced to low-voltage AC "hot"?

I have a requirement to drive a triac from the MCU powered by a DC/DC converter. The AC supply is typ 24 VAC @ Rc terminal with respect to C terminal. The triac is driven as follows. The MCU GND is ...
Kaush's user avatar
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Why are R1 and C4 connected in parallel to output in the following dimmer circuit?

I'm trying to understand the following dimmer circuit I found from this website: https://electronoobs.com/eng_circuitos_tut80.php: Why are R1 and C4 connected parallel to the Triac? I have read some ...
jjk's user avatar
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Do I need a snubber in a snubberless triac?

I am trying to make this circuit and using the Triac as a switch. I am using in this one a BTA06, although I will upgrade it to a BTA12 so it can handle 220 V 1000 W easily. It will be implemented in ...
Hazardous Voltage's user avatar
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Does this IC have an optocoupler and a triac built into it?

I am trying to use triac to switch an AC signal using a DC input on the gate terminal from a microcontroller. From my understanding you need a optocoupler when the DC to AC levels vary by a bit. So I ...
Alex's user avatar
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Triac Phase angle control Heating method

I purchased a soldering station (Product Link: Tenma 2064549. Just for give more idea. Not for taking about the product.) few years ago and replaced the heating element. After replacing heating ...
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Question about MOC3052 and BTA12 usage schematic

Hello , I would like to know your comments about Figure-1 and Figure-2 in this design, which I intend to use to drive a 3-Phase 1.5KVA Asynchronous motor. In Figure-1, R2 and C1 are used to avoid ...
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