Help please

[Ex-Bay]

Forgive me please, but I'm getting desperate.

I'm building a big (30A+) 13.8v PSU. I have the circuits I have used before (based upon that by GI3HXV) but I've included a 3423 crowbar chip in case something goes wrong and the voltage rises to more than that specified.

Rather than use the SCR trip, where the terminals are shorted thus blowing the fuse/s (ever lost a strange fuse at 3 am on a Sunday in the middle of a contest?), I'd rather open-circuit the supply by use of a MOSFET, IGBT or even SiC transistors (what happens after that is slightly immaterial, but it involves relays and bright lights). These, especially the latter types, have the advantage of being used to switching relatively high currents; but getting information about them (apart from some strange graphs and so on) is somewhat difficult.
I should, perhaps, explain I was raised in the era of Valves (that's 'tubes' for the benefit of those in the USA), and some of this stuff is still a bit beyond me.

So if anyone has information about using some of this more modern technology, I'd be Very Happy to receive some guidance.

PS. I've checked my copy of Horrowitz and Hill; no go.

 

[Old Timer Chris]

Did you solve this?

Did you solve this?

Born in about the same era many years ago! Largely depends on where the fuse is located. A varister might help or a circuit breaker and or RCD combination but I suspect you have through of that. Would need to know a little more. 30 amp supply...I'm impressed!

 

[Old Timer Chris]

Oh I forgot 'Age again!'

Oh I forgot 'Age again!'

There is also a Polly Fuse which resets after the supply is switch off. I assume the existing fuse is in line with the crowbar chip so when fault is detected the fuse blows protecting the rest of the circuit. If you can find a value of the right rating it should be a relatively straight forward change.

Strangely enough another you've found another weirdo who is interested in this sh--