What thyristor should I choose for this circuit?

Thread Starter

Matteo Guglielmetti

Joined Apr 30, 2018
Hi, I start this thread saying that this is my first post on this forum and that I'm not english so I could do some grammar mistakes.
I'm working on a coil-gun, here's the circuit:

The problem is that I am not able to choose the right thyrsitor, I've tried with a BT151-650R, but it died.
I've measured the resistance through the fire circuit, and I got .2-.3 Ohms, then I calculated the max current I could get at 48V and I got 240 Amps.
Can you suggest me a cheap SCR which can meet circuit's specs?


Joined Jun 22, 2012
You're firing the thyristor wrong, you need the Load L1,in the Anode leg, and a 1K resistor across the G/K terminals to prevent false triggering. The problem you have is the thyristor will Latch ON with DC.

You would be better charging a Capacitor with the DC and use that as the firing voltage, then when capacitor is discharged, the thyristor will turn off ready for the next pulse.