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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39 views

Triac never switch off

I designed this circuit; PRI_LO and NEUT are connected to 220v. The "high side" triac is Q4004D3RP (datasheet). I measure voltage at J2. Whatever is the command signal, I always measure 220v. I ...
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34 views

Triac-Circuit not Latching

I've built this triac test circuit here: https://320volt.com/en/triyak-tristor-test-devresi/ My transformer only delivers 10.5 V, however. I've tested some triacs which seems to work well. Both LEDs ...
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3answers
52 views

What happen when same phase is applied to both MT1 and MT2 of an AC triac

If same phase is applied to both MT1 and MT2 of an AC triac while it is OFF, will it spoil the Triac? Eg. BTA16. Context BTA16 along with MOC3021 is being used to control a 220V AC appliance using a ...
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25 views

FOTEK SSR replacing the Triac

I recently bought a few of FOTEK SSR-40DA relays believing that they are 40 A. Anyway I've burned one of then connected to my boiler, and I've opened it, and it turns out that they actually having ...
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38 views

Motor 1kw 220V AC controll using BTA16-600BW

I am trying to change an analog AC speed motor control to digital control. The analog configuration has a BTA16-600BW and uses DB3 as diac. The snubber components are 1K resistor and 47 nF. I tried ...
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18 views

Does a hybrid DC relay suffer from contact erosion (albeit much less than normal), or is it effectively eliminated?

Given a hybrid DC relay, I've been wondering if contact erosion is occurring (albeit at a slower rate), or if the design eliminates this entirely. (Assume that there is no snubber or other contact ...
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36 views

Detecting different heat element power

I have a range of heating elements with different power ratings (i.e. different resistances). Is there a way for my microcontroller to detect what power they are so I can use the microcontroller and a ...
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16 views

Connecting phototriac substrate to adjacent pins

For a regulatory exercise I am analyzing the result of a short fault between a phototriac's substrate (MOC3023) and its anodes (one at a time). The datasheet warns ...
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2answers
54 views

Opto Triac driver (moc3051) basic circuit problem

I wanted to try the basic circuit of MOC3051 which is a random phase optoisolator triac driver. I used this circuit from the datasheet: with following parameters: Vcc : 3.3v Transistor : BD139 ...
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2answers
42 views

BT136 inner resistance

I found two datasheets for the BT136 triac: Datasheet one Datasheet two But those datasheets didn't mention the inner resistance of the triac (or I couldn't find it.) What's the resistance ...
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60 views

Transformer open circuit output voltage and current limiting resistor at gate of Triac

Im kinda new to electronics and have some questions before i solder my projekt together. I want to make an Arduino controlled soldering iron and designed the circuit below. The optocoupler i used is a ...
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45 views

BTA12 Triac driver circuit

I'm using circuit in the picture as a replacement for a mechanical relay running a 40 watt 220 volt water pump. The problem is the circuit seems to be correct, but it doesn't work and I'm getting a ...
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20 views

Triac failure and Capacitive Transformerless Power Supply Load

I have done a dimmer using a PIC microcontroller (with a Transformless Power Supply), with BT137 (sensitive gate, four quadrants), firing on QII and QIII, and its load an old fashion Edison style 220V ...
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46 views

Triac Switching Circuit

I will switch an ac load with a triac. I am providing a dc voltage of 5V on the gate of first Triac and 0V on the gate of second Triac. In the first picture the triac is working and the switch is ...
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2answers
54 views

Why would a 3-Quadrant Triac NOT be Snubberless/Alternistor/High-Commutation?

While researching TRIACs, I came across this question: What's the difference between 3 and 4 quadrant triacs? Ok, straightforward enough, and that matches Wikipedia's explanation. However, I ...
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1answer
109 views

How can an optocoupler detect the zero cross point in an AC wave?

I am having some trouble using Triacs in order to dim a light bulb operating at 220V AC, I am a student at school and I don't have any background about using Triacs or Diacs or so, so I seeked the ...
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37 views

Firing Triac strategy for motor phase control

I try to design a replacement potter's wheel motor controller for an old potter wheel. I have solve some problem and I am able to control the phase standard of filament light. Now I try my board on ...
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1answer
41 views

Simple voltage presence monitoring with negative power supply

I am switching a 230-240 V load with a TRIAC and relay while also monitoring the presence of voltage on both ends of the load (i.e. not measuring the amplitude -- just that the switch successfully ...
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1answer
113 views

Need help to design efficient zero crossing CURRENT detector : clamp diode solution

I try to design a replacement potter's wheel motor controller for an old potter wheel. I have solve my zero crossing voltage detector and TRIAC command. Now I begin to understand the importance of the ...
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1answer
163 views

Help for TRIAC strange behavior

I try to rebuild an electronic board for an old potter's wheel. I try to build a "Phase Angle Control" with BTA16-800BWRG and MOC3043SR2M to control motor speed (the old board seem to use this ...
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1answer
128 views

TL431 crowbar simulation problem

I'm trying to simulate crowbar circuits, which is mentioned on page 8 of ON SEMI TL431 datasheet (https://www.onsemi.com/pub/Collateral/TL431-D.PDF). I'm using TINA TI for this. There are two circuits,...
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30 views

Demultiplexing analog fast signal for 2-axis piezo movement

I am driving a 2-axis stick-slip piezo stage. Currently, I have two controllers, one for each axis. However, I would like to know how can I reduce it to a single controller? I need a sort of a ...
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58 views

BT137 triac turns-on uncommanded

I am working with the following circuit, which is from the MOC3043M datasheet with a BT137 at the location of the unnamed triac: This circuit works fine for me if I leave the snubber out. However, ...
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31 views

RFI filter modeling in LTspice w/ triac

I have a few questions about modeling an RFI filter in LTspice with a triac-based dimmer circuit. I'm referencing the circuit described in Figure 11 in Triac Principles and Circuits -- Part 2 (Nuts &...
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51 views

Feedback on time-delayed TRIAC design

I would appreciate some feedback regarding the design I came up with. While I am not unfamiliar with electronics, this is the first time I actually designed something myself. The purpose is to solve ...
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22 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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59 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
156 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
32 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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90 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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120 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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42 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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152 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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45 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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44 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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107 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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127 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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34 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
68 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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31 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
75 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
38 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
38 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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755 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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134 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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111 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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42 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
240 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
236 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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