Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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.

Further reading:

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Triac versus Relay

What are the scenarios where Triacs can not replace a relay or vice-versa?
Daniel Grillo
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Why are relays still used in electric ovens?

I bought a new electric fan oven recently. It has a digital thermostat and control system. Yet much to my surprise, I can hear a relay clicking on and off inside it to control the power to its heating element. The oven is rated at 4kW (230V). I…
nigel222
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Choosing TRIAC snubber resistor for multi-purpose switching

I'm designing a circuit to switch a 240V AC load and haven't done a lot with AC power control before. I'm planning to use a Fairchild MC3043-M optically coupled TRIAC driver along with a BT138-600 NXP BT138-600 TRIAC. Referring to the following…
PeterJ
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What does a TRIAC do?

I'm hoping someone on here can give me a simple explanation of what a TRIAC does. To give this request some context, I'm an embedded systems software engineer, so I interface with hardware, but I have no formal training in it. I was looking over a…
Mike
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What's the difference between 3 and 4 quadrant triacs?

I'm looking at triac datasheets, in particular this datasheet for BTA16 series triac. The "electrical characteristics" section is split into two parts: snubberless/logic level (3 quadrants) and standard (4 quadrants). I have no idea what this is…
Roman Starkov
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Using an RC snubber with a triac. Is this design safe? (simulation included)

I'm designing an ac switch for a washing machine motor. No speed control is intended, only a switch to turn the motor on for 10 seconds and off for 10 seconds. I'm using a MOC3063 zero-detecting triac driver and a BT137-600E triac. This circuit was…
hadez
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What does the "proportional symbol" (∝) mean when used as a time unit prefix?

In several datasheets for electronic components, I have seen a ∝ symbol used as a prefix for a time unit, usually seconds, writing as ∝s. As far as I know ∝ is not a valid SI prefix, so what does it mean? What unit is ∝s? Comparing different…
Pep
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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 original plan was to use relays, more specifically…
Aksel
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Difference between Zero-Crossing Optoisolator and Regular Optoisolator

I am trying to find any documentation on what the purpose is of a Zero-Crossing Circuit TRIAC Optoisolator. The datasheets don't explain the concept well enough. If you do answer, please include references or explain how you found out. Thank you!
Daniel Donnelly
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Controlling High Voltage device with Arduino

I want to control lava lamps using Arduino. I think it shouldn't be hard project, but I have no experience with hardware projects so I'm not sure witch design will feet best for me. I consider using S202T01 Series Solid State Relays (I already have…
Maciek Sawicki
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Validate Triac circuit

I'm designing a device to switch a heating device driven by mains power. I've done quite a lot of research and realize there's a lot of information out there but as i'm dealing with potentially deadly AC i'd like to validate my design before…
Antti
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Digital Dimmer With Microcontroller

I want to build a digital dimmer for resistive Loads. I have found this circuit for that: The input voltage is 220VAC 50Hz. The red box in the picture is for Zero Crossing Detection. When the AC voltage crosses the zero, the Microcontroller will…
Mehrdad Kamelzadeh
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Difference between optoisolator(optocoupler) and solid state relay?

I have been looking into relays and optoisolators. I am aware that there are different optoisolators, with some having a transistor on the detector side which allows current to flow in one direction whilst there are others with triacs on the…
Jaimin
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How does the circuit of a basic variable speed electric drill work?

I am trying to 'automate' the control of an electric drill motor that I'm taking from a garden variety variable speed drill (from Harbor Freight.) It has a universal AC motor which I basically understand, a DPDT switch to reverse direction and a…
Cool Pontiac
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Why Snub an Optoisolator?

I am using an optocoupler and a power triac to switch 120VAC supply to an ~108 watt fan. The datasheet for my optocoupler requires me to snub the optocoupler output when I'm switching an inductive load (which I'm guessing an AC fan is). Why? I can…
Isaac Sutherland
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