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Questions tagged [triac]

A TRIAC is a 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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16 views

Triac gate and T1 short circuit forever with inductive load

I am using MOC3042 with BT139 and snubber 390ohm/2W and 10nF/400V to on/off motor from microcontroller, I can't find data about the motor as it's an old one but it drives quite large shutter
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37 views

Issue with universal motor velocity control by microcontroller

I'm using the circuit in the picture with a BTB12 600BW snuberless triac to control an universal motor (picked from a old washing machine, 220 VAC, 50 Hz) controlled by an arduino nano in customized ...
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2answers
114 views

Capacitor in parallel with relay coil backfires on contacts

I've got a smoothing capacitor(2,2uF) C1 in parallel with relay coils inside a fullwave diode bridge. When the circuit is closed through contacts in pre-relay RLY1 it first gives me, almost everytime ...
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1answer
23 views

Triac partial conduction without gate current?

I'm using the circuit below in a custom PCB to switch on and off an electrovalve. I assembled partially the PCB, just to verify some voltage across the triac. I didn't connect the MOC3021 and R40 at ...
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2answers
58 views

How triac acts as a diode and two transistor?

I'm constantly reading this fact that a Triac acts as a diode and two transistor. Can someone explain it.
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3answers
91 views

What's the role of the capacitors in this AC circuit?

I've been around electronics for a lot of time but I really didn't understand how capacitors work in an AC or DC circuits. I know capacitor has a big role in smoothing the output of bridge rectifier. ...
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29 views

Triac design for switching load to resistive heater

I'm designing a triac-based relay circuit to switch ac mains on-off to a resistive heater. The app note (AN-3004) for the opto isolator I am using, the MOC3061, suggests using a gate resistor value ...
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54 views

RC Snubber for Air Conditioner SSR

I have a window/Wall AC 2 Ton (240V X 15A = 3600W) I'm trying to control it via SSR to use Central AC thermostat board on it which is working good on fan level and all but I need a relay to switch the ...
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42 views

Why is my replacement triac not working?

I have a Hakko FX-888D soldering station which stopped heating the iron. I found out that the triac (which is a BTA06-600b) went bad so I went ahead and replaced it with a BTA12-600bw. It didnt work. ...
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41 views

Spurious microwave emissions perhaps coming from conducting TRIAC controlling AC power?

I have a TRIAC switch on an 240VAC single phase AC line. There is voltage on the gate as specified, there is a small dead band near zero. I.e. it is conducting as expected. However, I'm picking up ...
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1answer
56 views

AC motor control with triac or relay

I want to remote control (WiFi/Zigbee) a water pump AC motor, 1 phase or 3 phase depending on the case, with the smallest board size possible. I have used large motor AC contactor in past, it works ...
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1answer
96 views

How to switch 220 VAC? (Magnetic relay, SSR relay or triac)? [closed]

I want to switch 220V AC with a microcontroller. Before I used magnetic relays or SSR relays, but now I want to use a triac for this function (like in this circuit) and my load can be any 220 V AC ...
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27 views

Halogen 24V/150W light dimmer design

I have 64640 HLX (24V/150W) halogen lamp with 24VAC/300W power source and I want to design a dimmer to control the halgen light. I have two solution in my mind: 1- DC solution : using PWM and power ...
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1answer
55 views

RC Snubber For Phase Angle Controller

I have a phase regulator and I'm using it for regulating the RPM of a fan - centrifugal blower. The motor is a shaded pole induction motor (220VAC, 28W). The regulator is working fine, but if the RC ...
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30 views

Triac and Opto parameter checking

i'm looking to build and control a 220v ~150w heating element with an Arduino. for controling the load I was only able to find two 4n35 and a BTA12 triac. (one is for zero crossing detection) My ...
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2k views

Crowbar circuit causes unexpected behavior for op amp circuit

I am using an op amp to amplify an input signal from a microcontroller, which in general is working fine. For over voltage protection, I added the crowbar circuit taken directly from figure 32, page ...
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1answer
52 views

Triac power dissipation

I'm driving a high power load with the BTA440Z (datasheet): line voltage is Vac = 230 AC, load power is P = 1.33 kW, thus load current is ~ I = 5.8 A. If i swap the load with another ...
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1answer
27 views

I want to handle the voltage and current spikes from inductive load of 220V AC ceiling fan

I am trying to regulate speed of 220V ceiling fan from Arduino but unable to handle the reverse voltage and current though I am applying the flyback diode across inductive load.
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1answer
34 views

Triac circuit resistor tied to motor

I've run across a triac circuit which has a huge 510 ohm 50W load resistor tied to a 115V 1.6A PSC fan motor. I'm not quite sure what that big resistor is for. Ideas? simulate this circuit – ...
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2answers
275 views

How to test a TRIAC with just a digital multimeter and no external circuit

I need to fix an electric kettle and would like to test the health of the TRIAC BTA20. How would you test this component health with a digital multimeter - without any extra components and ideally ...
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1answer
123 views

Having a problem using TRIAC in my project:

I’m having a problem working with TRIAC (BT-131) in my project. I’m trying to switch a low power LED with a 5V DC output from a sensor. I’ve used an Opto-coupler (MOC3021) in between the TRIAC and the ...
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1answer
76 views

Resistance issue in a triac-optocoupler switch

I have made the following circuit to control my water pump with Arduino(UNO R3). I have tried many resistors (calculated myself) to limit current in the optocoupler and triac, but failed to carry the ...
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37 views

Triac Driver Datasheet - LED Trigger Current

Looking at the datasheet for MOC30xx (here: http://www.farnell.com/datasheets/1806097.pdf) I see the following note on p4 under the table outlining the respective LED Trigger Currents of the various ...
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3answers
91 views

How can I control TRIAC firing angle automatically with a DC voltage?

I have to build an analog proportional controller for a 127 V, 1 kW AC heating resistance. The power delivered to the heating element must be proportional to the difference between a set point ...
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1answer
139 views

Triac dimmer makes audible noise (hum or buzz)

I have some triac dimmer from IKEA (bought several years ago). This dimmer makes audible noise (hum or buzz), very notable during night when it is placed on a bedside table. I failed to find the ...
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1answer
79 views

MOSFET relay as an alternative for TRIAC relay

I use a 2 A TRIAC relay with non zero crossing from sharp in one application. Unfortunately I couldn't find this type of relay, and I want to use another relay (MOSFET relay 2A from TWOARD). Theses ...
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2answers
37 views

optocoupling a triac: correct pins

I was reading PLEASE BE AWARE THAT... the moc output MUST BE between the triac pins A2 and G it is never written in any datasheets but it MUST be so or your triac won't commute ... https://www....
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27 views

TRIAC based SSR output wiring COMPARISON

I want to use a triac based SSR (AQH-3213), I checked the datasheet wiring diagram, and it seemed simple. The problem is that its construction is the same as the triac driver optocoupler (MOC3041), ...
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1answer
54 views

Triac control circuit through load

Why is it that in every triac analog dimming circuit I find that the triac triggering circuit is fed through the load and not straight from the mains??
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1answer
84 views

What are the differences between triacs? [closed]

I need to replace a broken BT134-600E triac. I found out it's 600V 4A sensitive gate triac. Which of the following triacs can be used to replace the original one and why? MAC97A6 MAC97A8 BTA16-600B ...
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1answer
30 views

Triac wiring section

When wiring the power cables in a house, normative says wires must be typically 2.5, 4 or 6 mm2 in section for 230 V and 10...40 A. However, legs of a triac (thyristor, see this one by example) are ...
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183 views

Triac Switching circuit with Optocoupler

I am trying to control home devices using a microcontroller and a TRIAC. For switching, I intend to use an optocoupler and triac-based circuit. The circuit is given below (also plenty are available on ...
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114 views

TRIAC broke (literally) – why?

I have built a circuit according to Dimming 230V AC with Arduino, with two output channels. The basic principle is: An ATtiny does zero detection via an optocoupler; when AC crosses 0 V, it triggers ...
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2answers
50 views

Triac switch cause of heating

As a newbie to hardware design, I'm having some trouble picking components. I want to switch a 24V AC Solenoid valve using a triac. According to my research/experience, transistors heat up during use. ...
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2answers
52 views

How to connect power phototriac's gate pin?

I have inherited a design that uses a power phototriac (basically an optotriac with a built-in TRIAC) -- the VO2223B -- that includes a pin to access the power TRIAC's gate (pin 5 below). The ...
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1answer
74 views

Questions regarding eliminating hysteresis in ac dimmer

In the following circuit it says: “This hysteresis effect can be eliminated however, using the circuit from a detailed application note from Littelfuse shown in Fig. 6.4.4. Here the capacitor C1 is ...
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1answer
188 views

Driving Triac With MOC3021 for 12 v ac

i am using triac bt136 with moc3021 to drive 12vac but i found the problem is it possible to drive the triac on 12vac i made the circuit as shown in link on 12 vac but i didn't get any exact sine ...
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3answers
136 views

Use a TRIAC to connect/disconnect a capacitor to a PSC motor

In the image above, we see a PSC motor, with its 3 terminals, connected to a control board. This board has a RUN capacitor always connected to the motor. When the motor has to turn, the board applies ...
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1answer
157 views

BT136 TRIAC not closing on LOW signal to the MOC3021

I am trying to make an AC dimmer. I am following this schematics for my circuit, Circuit Link as you can see in the below picture that I am able to turn the signal on after a short while of zero ...
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0answers
45 views

Can't get my led bulb to turn on using triac and optocoupler

I have made the below circuit but my LED bulb won't turn on, although circuit works fine if replace the led bulb with a small led and ac supply with 5v dc supply. Can someone guide me in a right ...
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1answer
107 views

Problem with TRIAC simulation

I am trying to simulate a triac with MOC3020 but the MOC3020 does not output to drive the gate. The schematics is shown below: The waveform follows: Waveform with updated duty cycle to allow LED to ...
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188 views

Light dimmer circuit using triac gives fluctuating dimming

Light dimming using triac and optocoupler is very common and basic circuit, I have successfully tested the dimming for 1 channel (1 triac, 1 opto-coupler) now I want to add one more light dimmer with ...
2
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1answer
150 views

SSRs influenced by physical proximity?

This is part of a two-head EVSE. The two solid-state relays are used to drive contactors that supply high current power to the vehicles. I used to use a MOC3040 based triac circuit for this job, but ...
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1answer
87 views

Help for voltage is being passed trough load, even triac is OFF condition

We are using below circuit for home automation. We are facing problem when 5v battery is not passing to the circuit,but even 1 volt is being passed trough load, even triac is OFF condition.. Please ...
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138 views

BTA16 triac snubber and operation quadrant

I am working on a dimming circuit to be operated by an ESP8266. I have read a lot on this over internet and got a working circuit as well. But myself I am not satisfied with my understanding of ...
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2answers
186 views

Mains AC overvoltage protection using a TRIAC

I am trying to design a circuit that protects 127V appliances if plugged in a 220V socket (in Brazil 127 and 220V sockets have the same shape and it's easy to plug a 127V appliances in a 220V socket ...
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82 views

Best TRIAC for zero cross detection

I already asked this question Triac BT 136 getting shorted when load is given to T1. When I referred this link, I understood rate effect is the root cause for our problem. To avoid this either we ...
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1answer
163 views

Triac BT 136 getting shorted when load is given to T1

We have a optocoupler switching circuit which triggers the TRIAC with ZCD. Everything is working fine with all inputs. Connection is T2 as a input T1 as output Gate as Trigger from Optocoupler As ...
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2answers
102 views

TRIAC and Driver is heating up

I am trying to do a dimmer and below is my schematic. Before doing an actual PCB, I did a proto on a veroboard and the circuit works perfectly. Now when I did a PCB and got it back from the ...
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47 views

hump on rectified signal and inconsistency on gate signal

Following is the image of my circuit, I am working at the moment. This is not my own circuit but I am trying to understand and work on it. Following is the signal I am getting at Gate2. What could ...