Using a Thyristor (TRIAC) to Switch AC Line Power
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- Опубліковано 15 жов 2024
- In this video we look at how to use a Thyristor (TRIAC) as an AC line power switch. Great tool to use in home automation projects for turning on or off a light or building your own thermostat.
Another excellent tutorial and one of the most useful. This basic circuit can be adapted for so many AC power switching applications. Many thanks.
I liked this. The explanation of the components is easy to understand. Optoisolators in general tend to have white packages. Have seen them in white before. I believe the MOC303X series should be used in 115V applications.
Thanks for this. I need to switch ac power in my remote observatory.
The optoisolators are white to allow more light transmission within the casing. (via Colin's Lab)
I used a NTE3097 optoIsolator Zero crossing requiring 50mA max IF gate current by measuring a 2.87V drop across the Rvcc and using a 75 ohm R instead giving a 38 mA limit. Worked great using 100mW vs 330 mW rated for the device.
1. Are the two non-gate pins of the thyristor interchangable?
2. Why is the one clip attached to the heat sink? Does this go to the bulb?
3. Does the thyristor become hot?
Exactly what i needed. thanks
thank you so much sir for this simple thing
Excellent video, Thank you
How will the Arduino know when to trigger the gate signal of the triac? doesn't the Arduino need need some sort of zero cross reference to know about the AC phase?
Good education in the technical field
Really enjoy your content. Thanks.
thanks for the video can you tell me if my load is DC what do i need to use 500 volts and 20 amps ? i tried the SCR and as you said exactely it latches so its not a real switch , i need a switch DC 500 volts 20 amps please help
This video is for AC. For high power DC I would like at a high power mosfet or a mechanical contactor
@@ForceTronics i tried the SSR DC and somehow they get burned and just gets shorted , as for a contactor its limited to frequency ,i want to run at 400 Hz so no way to run with contactor and mosfet they get burn too how can i protect the mosfet ? \
Thank you soldier. this really helped.
thanks you for the neat clarifications. When you apply 5V at the VCC you dont exactly get 5mA flowing over the 1K resistor, you would get less, since the 1k resistor will have 5V minus the fordwad voltage of the diode, so you would get some 3.6mA ;)
Good observation, Amjad. I giggled LEDs and they can have a voltage drop from 1.8V to 3.3V. The datasheet for MOC3043M shows a typical Vf (Forward Voltage drop) of 1.25V, with max at 1.5V. Where did you get 1.4V from?
@@rongarza9488 hello Ron, 1.4V was only an estimation of the forward voltage in the infrared range. I think 3.3V and the like are for green and blue LEDs.
So nice
I think that the White bodied opto-isolators have a higher reflow temperature, at least that is the only difference that I see on the datasheets. It has been theorized that the material capacitance for the white bodied IC's is less, allowing quicker switching times, but I have seen no evidence of this on any datasheets.
Great - do you need any enhancement of the basic circuit to drive inductive loads (ac gate motor for eg) ?
Adding a snubber circuit should control the inductive spikes across the triac.
Hi,
I have an electronic board to control an AC motor -2500 watts/220v.
On the board are mounted two TRIAC - BTB24-600BW . The motor has a problem-runing on reverse only-no matter which button is pressed-FW or RW.
I found that the resistor who is connected to the Gate terminal on TRIAC 1 is burned and I replaced with a new one 47 Ohm/1 w .
Also I found a short cut between the Gate and Terminal 2 (the midle terminal) on the same TRIAC and replace it with new TRIAC--BTB24-600BW.After that I did a check by multimeter between all soldering points.
Then the board was connected to the motor.Unfortunatly the motor not run-in any directions- clock wise or reverse !
Do You can to gave me any advice?
What does Zero Crossing Circuit mean? It is shown on the schematic for the MOC3043M, in a box connected to pins 6 and 5.
Great vid, ForceTronics, thanks.
That is a circuit internal to the MOC3043 so I don't know exactly what it is made up of. My guess is it reads and does the appropriate action based on the opto sensor output. Zero crossing is probably a reference to now electricity crosses that plane, only light.
'Zero Crossing' refers to the point in the AC cycle where the current is zero. Triacs can only turn off at this moment, when the current is zero. (thats why triacs can't turn DC off - DC never 'zero crosses'). For a noise-free ac switch you need to turn the triac ON at 'zero-crossing' - otherwise the 'turn on' at full voltage will generate RF noise. Normal Speed Controllers are not 'zero crossing' and are very RF noisy. When you initiate 'turn on', this opto-coupler probably waits for 'zero-crossing' before turning the triac on.
I plan on powering a microcontroller (Arduino Uno) using a 9V battery to send a +5V DC output signal from a single pin that can provide 40mA to a TRIAC to be able to switch on and off a 24V AC solenoid valve. To protect my equipment from the discharge, im connecting a freewheeling diode across it.
The valve's electrical requirements are:
Inrush volt-amps @24 VAC - 8.5 VA
Inrush current @24 VAC - 0.35AMPS
Holding volt-amps @24 VAC - 5.5 VA
Holding Current @24 VAC - 0.23 AMPS
The solenoid valve is powered by a 24V AC @ 750MA transformer.
I am using an optoisolator as well to seperate DC from AC.
Can you confirm the triac (nte56050) and the optoisolator (MOC3041) are within requirements of the solenoid valve?
+Haitham Adwan If you look at the NTE56050 data sheet (www.nteinc.com/specs/56000to56099/pdf/nte56049.pdf) the max cont. current is 4A RMS and it can handle peak current of 25A so from a power handling perspective you should be fine. I have not used solenoids before so from a flyback protection standpoint I would go with what the manufacturer recommends.
I have a quick question, if I have a load that consumes around 5 A (Still good for any TRIAC) and I put a current limiting resistor around 18 Ohms (120 * sqrt(2) / 5) and is around 33 Ohm, but what about the wattage? That means that the TRIAC can handle big currents but the TRIAC cant?
I realize this vid is a few years old. Not sure if your still playing around with triacs or not. Have you used then to control 110ac motors (inductive loads)? If so do you have any recommendations based off of your experience?
I have not. If you look at the data sheet for the opto isolator MOC4043 it talks about the setup for highly inductive loads. They recommend adding a series cap and resistor in parallel across the input and output to handle flyback effects. They suggest some values, but you may have to do some trial and error to get it right.
+ForceTronics I have the data sheet and I do see their recommendation for the snubber, but my issue is it provides no recommendation for the voltage or wattage. It's kinda black magic to me.
Go to the Triac data sheet for that info. It provides voltage limits as well as transient time limits.
+ForceTronics will do, thanks for the advice and your time!! Your videos are great, keep up the good work.
For motors 110 ac and larger I feel its better to use a relay or a contactor as they can sorce higher current. I used a n channel mosfet to switch a 24 volt coil relay that sourced 120 volts ac at up to 15 amps. The relay switched a 3 phase motor contactor that was powering a 460 volt 90 amp motor. I used a 24 volt sensor, with voltage divider to signal an attiny85 mcu pin to go high or low, switching the motor off and on. The motor pulled 120 amps at 460 volts ac on start up then would pull 90 amps after it got to its normal operational rpm. Funny thing was the industrial electrical technicians I was working with just spent $1000 usd on a PLC to do the same thing I was doing for less then $20 usd in parts. Not counting the sensor, relay and contactor because they where the same parts being used with the PLC.
Thanks for the video. You can solid-state relay which is exactly the same circuit as the one you are using here. (S108T02 Series
S208T02 Series)
Nice
is it really safe to use switching of this moc3021+bt series triac instead of traditional relay , as we know relay provides around 10^6 click life and I have seen some relay contacts get sticked due to unknown reasons and we need to replace those and if they used in home automation it's really seems disaster so is it good idea to use triac as switch?
Bhavin Rathod relays are a good option for low switching frequencies. But since they are mechanical switches and will wear out in time and will require replacement. Using optotriacs, you can switch the ac load at a much higher frequency
In the datasheet I can't see what resistor should I use so that I can use it in 220V AC? May I know if there is a computation there? or what is the value of resistor shoul I use? Thanks in advance ;)
***** thank you sir =) Now I already saw it , but something I noticed sir, when we trigger the triac using optoisolator, when if it is off, our lamp is still on, but very very little brightness on it, I dont know how it is happened, But the value of 330 ohm and 360 ohm was replaced by 1000 ohm, because we dont have that resistor, correct me if I a wrong sir, Maybe the value of resistor has affected the output of triac?
I have similar problem. How do you solve it?
Hi sir,what is the use of triac in water heater?
I am not familiar with water heater circuitry. If there is a triac in the circuit chances are it is used to switch on and off AC voltage
my lamp is on by ttp223,
when the fan is running,
my lamp off / OR on .why?
I have no knowledge of your lamp's deisgn so how would I answer your question?? I suggest you take it to a lamp repair shop or just buy a new one.
super. thanks
I did the exacte schematic but wihout the optoisolator and my 1K resistor caught on fire :S oups. Should of Watch this before. Thanks!
Can i use this triac to switch ac power to turn on and off a 24V AC solenoid valve? the ratings of the valve are @ 24VAC 0.35 AMPS in rush current. Holding current of 0.23AMPS @24VAC
+Haitham Adwan Yes, you will want to add the extra resistor and capacitor in parallel with the Triac since a solenoid is an inductive load. I mention this in the video but it is covered in more detail in the data sheet of the opto isolator.
@ForceTronics I have a burning question that I hope you can help me answer. I connected the Arduino pin to leg 1 on the optoisolator and GND to leg 2 with no 1K resistor and it worked just fine. Why would you connect Vcc to leg 1 with the 1k resistor and the arduino pin on leg 2 then? Does that provide any additional protection layer? Please let me know.
Ivann Ruiz the data sheet recommends using only 5mA to turn on the Optoisolator so 1k resistor accomplishes that
Brilliant!
What is the purpose of 1K resistor on the AC side? I also find such resistor in MOC3061 datasheet but there's no explanation about it. Thank you
The datasheet does not say. Looking at the couplers schematic in the datasheet it looks like it is used to bias the active element in the coupler
Hello sir,
What protection mechanism to protect TRIAC From Overload Or High Current ?
Fuse or circuit breaker. The normal methods when working with AC
Why did you use the zero-crossing instead the regular One?
I don't understand your question, can you please provide more detail on what you are trying to ask?
Probably because 'zero-crossing' creates no RF noise? For a noise-free ac switch you need to turn the triac ON at 'zero-crossing' - otherwise the 'turn on' at full voltage will generate RF noise. Normal Speed Controllers are not 'zero crossing' and are very RF noisy. When you initiate 'turn on', this opto-coupler probably waits for 'zero-crossing' before turning the triac on. PS.. 'Zero Crossing' refers to the point in the AC cycle where the current is zero.
what is the watt value of the 180 ohm resistor you used in this project?
***** Thank you for the quick response, i must have something wrong in the wiring because the circuit works and the arduino switches the light but i get smoke on the 180 resistor after a few seconds
***** any suggestions as to what might be causing the overload of the resistor?
Can you show how to dim?
To dim the light use a pulse width modulated signal instead of a simple logic high / low pin. Adjust the duty cycle to control the dimming.
@@ForceTronics Thanks for the reply.
how do you determine the resistor value of 180, and 1k ohm ?
thank you
Those values were recommended by the datasheet of the opto isolator.
@@ForceTronics thank you for your respond.
what if i want to use 36 triac turn on and off each 3 triacs connected to on light ,
how i can control the turn on off , should i use 36 Arduino for each triac
+Aif Myham You would need 36 digital pins, but not 36 Arduinos. That is more like 2 to 4 Arduinos depending on which ones you use. Also if all 36 can be on at once be careful not to exceed the max current rating of the Arduino.
*****
Thank you if you can tell me how i can turn it off
+Aif Myham Turn what off the Triac? The video covers how to "open" and "close" the Triac as a switch.
***** thank you
How about 1 arduino and 5 74hc595? Should give you 40 i/o pins using only 3 pins from the arduino.
can this circuit be modified to be a light dimming circuit?
It probably could be used for that application. My concern would be that this method of dimming would reduce the life of common AC bulbs like incandescent or fluorescent since it is constantly cycling power to them.
Thanks a lot.
The zero crossing opto would need to be replaced with a random triggered opto to switch it when you want in in any part of the sine wave phase. The zero crossing will always trigger at the start of the next phase.
Correction: a thyristor and a triac are 2 totally different devices. A thyristor is a silicon controlled rectifier i.e. it converts ac to dc
Generally, SCR and Thyristor are used interchangeably but SCR is a kind of Thyristor. Thyristor includes many types of switches, some of them are SCR (Silicon Controlled Rectifier), GTO (Gate Turn OFF), and IGBT (Insulated Gate Controlled Bipolar Transistor) etc. But SCR is the most widely used device, so the word Thyristor become synonymous to SCR. Simply, SCR is a kind of Thyristor. And Triac is also a kind of Thyristor.
How can I convert 12v dc to 12v ac ?
You need to design or buy an off the shelf inverter. I am not a power electronics guy so designing inverter is not a video that I would do
Thanks a lot! :DDDD
This need necessarily the neutral line to work?
No, it does not.
The lines should not be labelled 'hot' and 'neutral'. They should be labelled 'hot' and 'switched hot'. If someone hooked the circuit up as you show, they would short hot to "neutral" and cause a boom. BTW it is not a neutral unless it is in a 3 phase system. In a normal single phase 120v system it is the 'identified conductor'.
Hello
I want to switch a relay 220v with triac
I use bt136 and moc3063
I have big problem when main phase or natural off and on
Relay is on and off too
Do you know what is wrong to solve my problem
And can I have your WhatsApp number to send my test and circuit diagram