A TRIAC is an 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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Traic switching in 3+ quadrant

I am controlling fan speed using Triac phase control with a circuit similar to this. The problem that i am facing is that my triac burned out after using it for 2 3 days and after burning it will ...
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36 views

Stress test on triac - BT139

I am working on this project. The project involves phase control of an ac appliance such as a fan or dimmable bulbs. My circuit was getting affected severely due to nearby electrical sparks most ...
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99 views

AC fan speed control (using Arduino)

I wanted to control a 220V, 50Hz AC ceiling FAN using PWM output from an Arduino microcontroller and I have referred to several resources regarding this. Resources I referred ...
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69 views

Why do we prefer zero-crossing optotriacs for driving triacs?

I usually see a special type of optotriac which has internal zero-crossing detection circuit in it. This type of optotriac is generally used for driving triacs. But, I don't understand its necessity. ...
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27 views

How to correctly simulate Zero Cross Detector Circuit?

I am trying to simulate a circuit for Zero Cross Detection. The end goal is triac phase control. My simulation using proteus hangs up and with message "Simulation is not running in real time" and ...
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82 views

Wired Or of Triacs don't seem to work

I am trying to make a full sine wave from two half waves wire-ORng through triacs However, as long as the triac output terminals (MT1 for both) are not shorted, the signals seem fine. When I short ...
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57 views

High Voltage Triac Control

I'm trying to control a universal motor run from a 240V power supply using a micro-controller. There is a existing PCB that uses a potentiometer to vary the speed that I am trying to replace. I've ...
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2answers
62 views

Triac circuit confusion

X1Iz.png I have the following questions about the above circuit: -Why are we even using a trica/diac combo above. Why would a circuit consisting of just the fuse, switch and primary not be ...
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40 views

Switching 150kHz mains for an LC load

I'd like some input on whether or not to use a mechanical relay or some form of SCR setup to change the capacitance in my LC circuit that is currently operating at around 170V, 1A at 150kHz. (Not ...
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2answers
79 views

Arduino Dimmer Shield Schematics Interpretation

I've read so much about Thyristors, Triacs and Rectifiers on the last days that I'm almost understanding my schematic, but I'm not there yet - I need some help. Overview: I'm making a home automation ...
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124 views

Why do we use a diac for triggering a triac?

I mean, Wouldn't it be possible to give a gate pulse on triac directly? I have seen in many phase control application circuits like fan speed control,the usage of diacs to trigger a triac.
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155 views

Short circuit protect for Triac

I'm going to use this circuit to control some lamps. As I know a short circuit would cause the Triac to burn very fast and I need a way to protect it. Using fast fuse is cool but I need to know If any ...
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160 views

Turn a mains light on slowly

I've been looking at creating a simple circuit to slowly turn a halogen daylight bulb on over about 30 minutes as soon as power is supplied to simulate dawn. I've got a 240VAC 42W halogen bulb that ...
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130 views

Will replacing the MOC3024 with MOC3021 make any change

I'm student of 10th grade and new to electronics I'm trying to make a switch to control appliances which runs on AC mains and I don't want to use any relay see the circuit diagram from the link to ...
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137 views

Filtering out TRIAC's triggering current spike on the mains

I've got my 2KW heater controlled by a home-made dimmer, on 230V/50Hz mains. It's using the common TRIAC delayed command process. The TRIAC (BTA24-800BW) is a snubber-less kind, drived by an (non zero ...
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2answers
684 views

Do I need zero-crossing detection for controlling a heater?

I need to control a heater element (about 500W) using arduino. For switching part I would go with zero-crossing SSR or zero-crossing optoisolator and triac (the second seems to be cheaper). The ...
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105 views

Driver for triac

Can you explain this schematic: Especially part where are optotriac and triac. I can't understand why if turn on optotriac \ then main triac will be open. Because I made a real scheme and ...
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251 views

Water pump with opto-isolator MOC3063M and triac BT137

I have designed a circuit for water pump. Please correct me if I am wrong with schematics. The idea is to to switch on/off AC motor pump with 230V and 7.5A, when water is detected. I have used ...
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154 views

Dimming SSR Circuit - Verification

I am designing an SSR circuit for the purpose of controlling Christmas lights. Specifically I have the following two goals. Switching & Dimming incandescent strings Switching LED strings - I ...
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181 views

Triac power switching

Given the circuit below: (I simply plan to switch the light bulb on/off and I will later add an optotriac to the gate.) As I understand, the circuit should work in this configuration, and the ...
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238 views

TRIAC turning on asymetrically by itself when it gets warm

I've got a simple triac phase angle controller which is very similar to the MOC3021 data sheet app circuit. Most of the time everything is fine. The circuit looks like this: The triac is a ...
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5answers
472 views

How to throttle power consumption of a heating coil?

Which is an appropriate but simple electrical circuit to reduce the energy (power) consumed by a heating coil which has an AC feeding without generating an asymmetric load (large DC component, e.g. ...
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2answers
170 views

How to replace the rectangle(DIP) bridge rectifier with round one.

I want to make an AC dimmer and the circuit diagram from the instructables uses a bridge rectifier which is in DIP package and rectangle in shape and the rectifier which I have is round one, so how ...
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56 views

triac DC ground and AC live

In this example of using a 3Q triac, could the AC voltage flow into the DC terminal?
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222 views

How fast should a Triac be switched for a dimming application?

I want to create a dimmer using a Triac - it will have a duty cycle where it is on for x% of the time, and then off for Y% of the time - my question is how often should this on/off cycle happen? I ...
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415 views

Snubber causing more problems than benefits

When designing and building a simple motor controller i used 2 snubber circuits, one to protect the main triac and another one the smooth the communication between the phototriac and the main triac. ...
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448 views

Where should I place the capacitor in this TL431 + TRIAC crowbar circuit?

I'm building a replacement power supply for my C64 and want to add some protection against overvoltage. For that purpose, I tried to find a suitable crowbar circuit that would short-circuit the supply ...
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97 views

Controlling AC devices using ATmega8

I have an microcontroller ATmega8, TRIAC MOC3083 and thyristor M166P. I need to develop and device which will turn on/off lamp(220V). But while I'm developing I don't want work with AC 220V now, DC ...
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68 views

Snubberless TRIAC not turning on in negative cycle

I have a simple circuit with a MOC and Snubberless TRIAC. I am using the ST Snubberless Library for my simulation. I cannot understand why the TRIAC does not turn on in the negative half cycle, even ...
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294 views

Standard Relay vs SSR vs TRIAC for Switching CFLs

I'm confused weather I should go for a standard electromechanical relay (EMR) or a sold state relay (SSR) to switch CFLs @ 220V with 100W max load. This is for a commercial product with the following ...
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102 views

Lamp flickers if dimmed up to an extent

I used circuit shown in this instructable to make an AC dimmer but everything goes fine if not dimmed much but then it starts flickering because of voltage fluctuation. ...
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86 views

Using triacs to switch more complex equipment than just motors and lights?

Obviously triacs have been well known to be used in applications which don't really require a perfect sine wave to function. However, what about say a triac to switch on and off more complicated ...
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683 views

Controlling a 1000W radiant heating element with dimmers

First I would like to mention that I am a stranger to electrical components and I come from a mechanical engineering background so please keep that in mind when answering my question. I am trying to ...
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146 views

Device to switch a 220VAC/40A resistive load

I need to switch a 220VAC/40A resistive load. I only need on/off switching, no phase control. I would like to avoid mechanical (moving parts) components if at all possible because of reliability ...
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176 views

Triac motor controller

I have build a circuit with the purpose of driving a ~1000VA AC motor. The motor controller fires a triac only at zero crossings. The circuit is as follows: simulate this circuit – ...
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3answers
315 views

Light activated switch - avoid flicker when turning on

I have a small light bulb (3W LED, E27/110V) that I am controlling using based on ambient brightness (it comes on when it is dark, and goes off when it is light). The circuit uses a BT136 triac, a ...
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570 views

Design of “simple” 1000W AC motor/ heating element controller

I have been working on designing a circuit which can reliable control the on/off cycles of a 1000W (vacuum cleaner) Motor and a 1000W Cartridge heating element. It should be noted that the motor and ...
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2answers
148 views

Voltage drop across 3Quadrant triac

I am going to start off with the disclaimer that I have a Software Engineering background and very little electrical engineering background. I am using a 3q triac on a breadboard circuit. My gate ...
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2answers
290 views

Simple light bulb operated by button and optoisolator triac

I'm new to the world of electronics and I have a quite simple question. Can I control my light bulb with something like this schema? Power source is regular AC 230V (~320Vrms) source. Here is ...
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1answer
104 views

TRIAC with AC plug

I would like to do a small project where I could control an AC PLUGusing a digital signal. To do that, I would need to attach a TRIAC circuit into the AC plug. All it has inside is a fuse so this part ...
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1k views

Solid State Relay Vs Triac

The general and simplified view of my circuit is something like that: Using a microcontroller I want to select between two sound signal sources (S1 or S2). S1 is a signal that comes from a ...
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106 views

Measuring the output of a phase control triac

I have an air compressor I'm trying to troubleshoot and I'm trying to determine if the problem is with a small circuit board with a triac. The board takes as input an ac wall outlet (US) and outputs ...
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97 views

Activating Triac, signal conditioning

I need help with the following circuitry. Basically it is a correction of a bug in one of my company's products, an automatic glass door controller. What it is meant to do is when I give the lock ...
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2answers
170 views

Any negatives using a Triac to transmit square wave?

I want to use a TRIAC as a switch to open a gate to transfer a 9600 baud rate square wave (for a uart communication between two avrs). Currently I'm using dc relay, but I'd like to use the Triac to ...
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450 views

Control AC load with microcontroller. TRIAC behaviour problem

As per the title of this question i'm trying to control an ac resistive load. So far i had little success and i'm experiencing "strange", to me at least, behaviour from the triac(s) i tried. first of ...
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854 views

MOC3010 & BT136 with Arduino as trigger to power AC light

I've spend days debugging this circuit and have exhausted all possible solutions. I'm trying to use an Arduino PWM pin to light a 120V AC lightbulb. In order to do this I'm using a MOC3010 ...
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161 views

Missing phase 3-quadrant TRIAC-based solid state relay for 3-phase engine

First of all, I'm a simple mechatronics technician student first time posting here, so please don't mind if I say something that seems completely stupid, since I consider myself to be a total newbie ...
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1answer
314 views

will snubber pass voltage thourgh it?

We are doing home automation project. In that we are using triac for ac switching and snubber circuit (R=100ohm, c=10nf) for its protection. Here we have inductive and resistive load, for inductive ...
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2k views

LTSpice, MAC97A8 TRIAC model, Vgs error

I'm having some difficulty getting LTSpice to like a TRIAC model. The specific error it throws is "Missing model definition for VGT-0.65". The trouble is that VGT is a subcircuit parameter, not a ...
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570 views

Controlling Triac w/optocoupler, need some help with optocoupler datasheet

Loads: Some baseboard heaters (1500W max, some motors, 12A max). I have no experience using Triacs and optocouplers. Triac: T3035H-6T, Datasheet: ...