Hello. My name is Paul Pri. Sorry to disturb you.

Is there any way I can control the SCR time on and off with 555 timer? Is there any circuit that you have or can make that would be able to control SCR on state and off state? I need to be able to adjust time on from 0.1 second to 10 seconds and after that - off till next triggering. What I want is to be able to damp low voltage and high current through SCR to do a CD spot welding of thermocoupling wire. Any help will be appreciated. Thank you for your time.

Paul

 

Yes, you can certainly do that easily for AC. For DC, on is easy, off is harder. Google 555 SCR and see what develops. One thing to watch out for is that the cathode of the SCR needs to be common with the 555
circuitry unless some sort of isolation is used. Be careful and have fun.

Regards

cww

 

Hi Paul,

Years ago I made a thermocouple spot welder for a firm stress relieving pipe welds. I'm not sure why you need the variable On time as the capacitor will fully discharge each time before the SCR can turn Off.
Perhaps we can discuss off forum.

roy_matson at yahoo . ca