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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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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1answer
600 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 ...
2
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1answer
743 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
860 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
94 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
577 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 ...
2
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1answer
423 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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1answer
2k 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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2answers
636 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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3answers
449 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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1answer
1k 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
425 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 ...
3
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1answer
854 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 ...
3
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1answer
258 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 ...
2
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1answer
814 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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1answer
940 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
409 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
1k 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
485 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
343 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 ...
10
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2answers
15k views

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 ...
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2answers
542 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
436 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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1answer
269 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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1answer
266 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 ...
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3answers
2k views

What is the holding current on a triac?

What does the Holding Current characteristic mean on a triac? What does this mean for switching loads less than the Holding Current? For example the Sharp S108T02 has a max 50 mA Holding Current.
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1answer
2k views

is there any spice model for optoisolator triac driver circuit?

I have to design a phase angle dimmer using a triac. For this, I have read How do I drive a TRIAC from a microcontroller (for low voltages)? This forum really turns out to give me a good solution ...
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3answers
5k views

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 ...
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1answer
2k views

simple triac current limiter

I have a 20 liter electric storage water heater which has a 230V AC, 2KW electric heating element. The heating element is failing frequently primarily due to bad quality of water inducing faster ...
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3answers
6k views

TRIAC dimmer, circuit design help (resistive load)

Okay guys, I've been tasked with making a light-dimming control system for a 240V heat lamp dissipating around 250W. I need to adjust the heat output on the lamp by control from a microprocessor. I'm ...
4
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1answer
340 views

Sometimes the triac actuator doesn't turn off

The TRIAC actuator of a DC motor through a bridge rectifier. I activate a DC motor from the mains through a TRIAC (BTA16) in series with a 10 Ohms resistor for the inrush current limitation, in ...
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3answers
945 views

Multiple motor speed control with a single triac

I have a requirement where I have to control the speed of 10 motors. The motors are 230V AC single phase motors. The speed of the motors need to be increased or decreased using a electronic controller ...
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2answers
354 views

I need help matching parts

Link1: http://ww1.microchip.com/downloads/en/appnotes/00954A.pdf Link2: http://arduino.cc/playground/Code/ACPhaseControl Simple version: I want to use a picMicro 5v microcontroller combined with the ...
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1answer
453 views

Do multi-channel opto-triacs with common pins exist?

I am designing a circuit with many (4-128) copies of the same component. It's a 4-pin opto-isolator with opto-triac output. I am aware that the pin spacing and package width can't be much less in ...
2
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2answers
825 views

Questions regarding Triac Driver circuit

Sparkfun's EL Escudo Dos breakout board uses this circuit for an EL wire driver channel, with R2 = R3 = 330. I was wondering what the function of R2 and R3 is? Are they required? What would happen ...
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19k views

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 ...
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3answers
330 views

TRIAC Dimming for LED Buck controller circuits

How can you create a solution for a LED constant current driver that can handle TRIAC dimming? Can you convert the waveform into a PWM and is there a simple solution?
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6answers
7k views

How do I get proportional 240V AC output from an Arduino-based PID controller to “dim” a rice cooker for a Sous-Vide project?

I'm making a PID controller for Sous-Vide, using an Arduino. I'm trying to decide how to control the output. Using an SSR as an on-off switch on 240V AC will probably give me the result I'm looking ...
6
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2answers
15k views

How do I drive a TRIAC from a microcontroller (for low voltages)?

As a followup to this question, I would like to figure out how exactly one might go about driving a TRIAC from a microcontroller (for low-voltage applications, such as 24VAC). Imagine a scenario where ...
5
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5answers
3k views

What would a professional use to switch sprinkler solenoids?

As evidenced by several previous questions of mine, I'm working a project to design a sprinkler controller. This involves driving one of 16 solenoids (well, probably only one at a time...) based on a ...
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3answers
5k views

Trouble with triac driven dimmer circuit

I have a dimmer circuit that produces the following wave forms. Red: Triac Gate Signal Yellow: 120v 60Hz AC Wave (not triac output) I would assume that given this signal, the triac should flip on ...
5
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1answer
2k views

Troubleshooting a Triac Motor Control Circuit

I have a Xytronic 988 soldering station. It has a regular soldering iron on the left and an iron with a vacuum pump on the right. It has served me well over the years and one day when I was swapping ...
2
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1answer
2k views

Arduino triggering a TRIAC for EL Wire, no optoisolator

I have been researching and looking up how to control EL wire online and I will be using the same layout as the EL Escudo shield from Sparkfun but just for one strand. Basically: Arduino (+ resistor) ...
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4answers
1k views

Optotriac doesn't turn off

I'm using an opto triac, specifically the MOC3041, with a zero crossing circuit to switch the Tx pinout on an RS-232 interface. I have no problems turning it on, but after I unload the input (no ...
3
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1answer
2k views

Modding a dremel to accept 230volts

I purchased a Dremel tool from the United States and using it in India. As always, the trouble is with the power inputs. A step down converter is simply too expensive for those power ratings (>2 Amps ...
2
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2answers
554 views

Looking for and SMD optocoupled TRIAC

I'm looking for a SMD optocoupled TRIAC part for driving EL Wire (110VAC, 1000Hz, low current non-resistive load) with an ATTiny85 pin (TTL, 20mA max) running at 3.3V. The previous design used the ...
5
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3answers
3k views

SSR vs optocoupler with TRIAC output

I've designed (and mostly implemented, now) a system for turning on and off 24VAC solenoids. In order to achieve this, I used optocouplers with TRIAC output (Sharp PR26MF1xNSZ series). The datasheet ...
7
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3answers
9k views

When should I fire the TRIAC's gate when controlling an inductive load (AC motor)?

I'm using a combination of opto-triac + TRIAC to control a 230V AC motor with a microcontroller. For detecting the zero-crossing of the voltage I'm using another optocoupler. I know that the AC ...
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2answers
1k views

What does 'random phase' means in a triac driver?

I'm using this triac driver to control a triac. In its datasheet it says 'provide random phase control of high current triacs [...]'. What does that mean? It doesn't have zero-crossing detection?
5
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2answers
2k views

Is a protection diode needed on a TRIAC optocoupler and what for?

Please refer to page nine of the Sharp S108T01 / S108T02 datasheet: Is this diode needed - why/why not? How do I choose the correct diode, if yes? UPDATE: Thank you all for your educational ...