Thanks for the schematics; most informative. I have a question and would appreciate an answer if possible. I wish to use your circuit to control a home shop spot welder. This is quite a serious machine and has an inrush current of 70 amperes at 115 VC. I have the power line that supports this safely, as the welding pulses at that power level are typically 1/2 second. So, to handle that inrush current, are 2 SCR with inverse-parallel connection, sufficient with a 150 Ampere rating each, sufficient? Secondly, for triggering, can the optoisolator be directly replaced with a solid state timer? I'd like to use one with say 0 to 10 second on-time. Thank you kindly for your time and patience with this matter.
Hi @BasementEngineer! Very nice to see you. How is your matter now? I think TRIAC or SCR all help solves your problem. With spot welder, this is a pure resistive AC power load that you can use my simplest version of my project that is "using mechanical relay to turn on off AC power at zero-cross". You can visit th-cam.com/video/YNzEnEqZPHI/w-d-xo.html to watch the video. If you are really interested in this I can help you. Hope to see you soon
Hi, How can I take variable output through scr.. by controlling gate in put voltage say upto 20 amps output, is there any circuit. This is for making battery charger.
This circuit will do just that with the correct SCRs. You have to use a microcontroller with a zero crossing detector to phase control the output. See www.bristolwatch.com/arduino/arduino1.htm
A short circuit will destroy the triac. While building this use a low-power triac and a current limited power supply untile you are sure it is working. I used a low-watt light bulb in series with the power supply.
Very much appreciated, clear unhurried, patient explanation.
Thank you!!
WOW!!! THANK YOU, FOR THIS CLEAR, AND CONCISE LOOK ATE THESE CIRCUITS, AND HOW THEY FUNCTION!
Very nice video, explains step by step the functioning of the triac circuit.
How I can vary bulb intensity in the circuit you are demonstrating on 5:00 at the video.
Can I vary input voltage of optocoupler or duty cycle??
I was wondering why tying the 2 gates together wasn't working in my circuit...thank you so much for the explanation!
Welcome
Thanks for the schematics; most informative.
I have a question and would appreciate an answer if possible.
I wish to use your circuit to control a home shop spot welder. This is quite a serious machine and has an inrush current of 70 amperes at 115 VC. I have the power line that supports this safely, as the welding pulses at that power level are typically 1/2 second.
So, to handle that inrush current, are 2 SCR with inverse-parallel connection, sufficient with a 150 Ampere rating each, sufficient?
Secondly, for triggering, can the optoisolator be directly replaced with a solid state timer? I'd like to use one with say 0 to 10 second on-time.
Thank you kindly for your time and patience with this matter.
Hi @BasementEngineer! Very nice to see you.
How is your matter now? I think TRIAC or SCR all help solves your problem.
With spot welder, this is a pure resistive AC power load that you can use my simplest version of my project that is "using mechanical relay to turn on off AC power at zero-cross". You can visit th-cam.com/video/YNzEnEqZPHI/w-d-xo.html to watch the video.
If you are really interested in this I can help you. Hope to see you soon
en tu diagrama dices que los SCR son de referencia BT 137 pero estos elementos no son SCR sino TRIAC
Don't you mean the 2 SCR's are thyristors instead of triacs, like a TIC106M. The symbols @7:50 are thyristors....
The component showed in the video and webpage (BT137-600) is a Triac, built the circuit with scrs and it didn't work.
I have not completely understood. How many volts are the gates of the SCR powered?
SCRs are current operated not voltage operated. The current is fairly low but wide range.
Very good 👍👍
Hi, How can I take variable output through scr.. by controlling gate in put voltage say upto 20 amps output, is there any circuit. This is for making battery charger.
This circuit will do just that with the correct SCRs. You have to use a microcontroller with a zero crossing detector to phase control the output.
See www.bristolwatch.com/arduino/arduino1.htm
can we control the lightbulb without variable resistance? so that it works as soft starter
What variable resistance? You can just switch it off-on by turning on the optocoupler(s).
HI! is that a single phase ac voltage controller?
Yes.
Thinks
Iwould like to use that for high power like 380v AC
380V X 1.41 has a peak voltage of 536V, use 600-volt parts minimum.
@@LewisLoflin thiks at fiesta
Ihave to change the value of every part
@@mohmedahmed-vw2us This was built for 120V AC (peak 170) so 380V is very different.
@@LewisLoflin can you train to suggest somme part ?
Very informative video
How calculate The value resistor thanks
They are not critical. I took these values from the spec sheet.
Hi Lewis can triac handle been short circuited I would expect this to cause failure of the triac ie fail short
A short circuit will destroy the triac. While building this use a low-power triac and a current limited power supply untile you are sure it is working. I used a low-watt light bulb in series with the power supply.
Excelent video
thanks very much man. 🙏🙏🙏7
i think the diagram at the beginning is wrong. The two scrs should only be connected to one phase.
That at the beginning was factory spec sheet.
Yjanks