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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Variable Plug Outlet 110~120 VAC [on hold]

I have a lamp in my newborn son's room, and like many lamps, it's on/off switch makes noise, which he does not always like to hear when falling asleep. Do they already make some sort of TRIAC style ...
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60 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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59 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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62 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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1answer
73 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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1answer
35 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
121 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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89 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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49 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
113 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
70 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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3answers
365 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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43 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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67 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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133 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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205 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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342 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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116 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
178 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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788 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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1answer
254 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: ...
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128 views

Relay/TRIAC for water heater switching

I'm designing a remote controlled switch for my water heater and I am bothered by the following questions: Should the switch be DPST, or can I just switch the phase line (dangerous?) ? can I do it ...
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258 views

Problems running a triac dimmer off a UPS

I built a circuit (like the one below) to control an incandescent light bulb from an Arduino controller for the digital input. I did not use the zero crossing part of the circuit and mine is ...
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340 views

Triac and Optoisolator not turning on lightbulb

I'm trying to switch on a lamp using a microcontroller. I've wired the schematic below using a 5v power supply instead of the microcontroller for now and the first time I turned on the lamp the ...
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1answer
137 views

Triac substitute for BTA12 600TW?

Can I safely use a Triac at a higher specification than designed? e.g. for a BTA12 600TW, could I safely use a BTA18 800TW i.e. where the volt & amp values are larger than the spec?Thanks for any ...
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314 views

Using optoisolator and triac with mcu to switch light on/off--need low power alternative

I'm using the schematic below to control a lamp (light bulb) with a microcontroller and I'm running the mcu (and moc3010) off of AA batteries. I just realized the moc3010 has an LED in it that needs ...
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288 views

Can a triac which is driven by another triac be used for switching AC continuously?

MOC3041, BTA06 I am considering cascading two triacs like this in order to make a solid state relay. I'm not going to control the phase angle of the voltage on load as done in dimmers. I only want ...
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1answer
557 views

why does the microcontroller pin driving optocoupler is giving 2V even if it is set?

I have interfaced pin 1^1 of Atmel AT89S51 to optocoupler MOC3041 IC, I set this pin to logic high. I have connected 220 ohm resistor and red led and then pin 1 of the optocoupler and after that ...
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2answers
544 views

Heater buzzing in AC triac circuit

The problem is that my 1200 watt conventional heating element is creating a mechanical buzzing noise. Shown below is a schematic of my setup: PD4 is the output from a 5v microcontroller and is ...
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2answers
92 views

Digitally Switching a Single Source into 128 Channels

I have a device I'm building that uses a single high-precision current source (driven by a DAC for various arbitrary waveforms) to drive one of 128 channels. The current level will be on the order of ...
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1answer
390 views

Controlling multiple triacs with microcontroller for light dimming: where to use optoisolators

I want to control (dim) multiple mains lights using triacs and a microcontroller. (One triac per light). I want to keep both the costs and component count as low as possible. Is it necessary to have ...
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1answer
263 views

Isolated vs non-isolated triacs

Bt136-600 is an example of a non-isolated triac, while BTA08 is an example of an insulated triac. What is the difference between an isolated and non-isolated triac? They seem to have the same symbol ...
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1k views

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 ...
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378 views

TRIAC gate resistor keeps getting burned

R85 in the following circuit keeps getting burned out when the photo-triac is turned on. It may last for a few minutes before burning out. It is a smallish 1/10 W resistor, while R83 is in DIP ...
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296 views

Mains triac safety circuit design

I am investigating using a triac instead of a relay to control 250V 10A devices. However all the 600V 16A triacs come in TO-220 packages. According to AS/NZS 3100 and AS/NZS 60335.1 I need at least ...
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623 views

TRIAC switching problem

I have a speed control circuit for a 230V AC motor. It has a BTA16 TRIAC for phase control and it is driven by an optocoupler MOC3021. The trigger signal is coming from a PIC16F676 microcontroller. ...
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1answer
313 views

Using a triac to switch audio signal for laser maze

So I'm building a laser maze for a science project for high schools, where we have lots of mirrors and the laser bounces around the room, when it hits the detector I want music from a source to switch ...
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1answer
530 views

How to design a snubber for optotriac

I've seen in several places this snubber circuit composed of 2.4K and C1 in this particular case. My question is - what's the purpose of this network exactly and how are the values for the ...
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1answer
194 views

What should I take in account when using a more powerful triac?

I'm familiar with simple dimmer circuit, now I want to build a more powerful triac unit to use with a high power heater. The resistance of my heater is made of 9\$\Omega\$ 3mm diameter nichrome ...
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1answer
510 views

Mixing AC and DC power in a circuit

This is likely a noob question, apologies if the answer is obvious. I'm trying to control a furnace using a 3.3V microcontroller. The furnace operates by connecting a common 21V AC "hot" line to one ...
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685 views

How do I select an optoisolator to both provide zero crossing to a uC and controll a triac?

This application note states that zero crossing detection can be achieved in an AVR with just a couple of resistors. However, it forgoes galvanic isolation and this is not acceptable for me. I would ...
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2answers
305 views

Triac connection for my project

TRIAC can be connected in series of 230 V. Shall I use mutivibrator for giving gate triggering this TRIAC? Also, how can I turn off this triggering by giving an external signal?
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4answers
951 views

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 ...
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2answers
290 views

Help me understand triac maximum current and when to use a heatsink

Datasheets list , under Absolute Maximum Ratings RMS on-state current = 16 A, for example. 1)How do I know if this is free air maximum current or properly heatsinked? 2)How can two triacs in ...
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1answer
263 views

How do I limit the maximum power, delivered to a heater, through a triac?

I am using the following circuit to turn ON/OFF a heater. Works like a charm. However, I would like to limit the maximum power delivered to the heater. The reasons for this are: the heater is a ...
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13k views

Choose 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 ...
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2answers
393 views

Can electronics be damaged by plugging into a lighting dimmer circuit?

So my stupid room is wired so all of the lower receptacles are driven from the electronic wall dimmer. Stupid me plugged in my brand spanking new brother laser printer into the lower receptacle. It ...
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1answer
350 views

Why do they add a TRIAC after an MCP3020 optocoupler?

I have a relay circuit (I use it instead of a relay) that uses a MCP3020, which I think does the physical separation of the two circuits (it's a LED and a photo cell inside a chip) and a BTA08 TRIAC. ...
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201 views

Triac datasheet values

I have a Triac that I want to use to control low voltage (~16 V) AC. The data sheet is found here. It specifies that the peak gate voltage is 5 V with a peak current rating of 2 A (which seems quite ...
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242 views

Calculating max wattage load for opto-triac

Are there any guidelines? Do the guidelines differ depending on resistive/inductive/reactive loads? For example, the Vishay VO2223A is rated up to 1A. At 110V it seems it can switch up to a 1 A x ...