I have a circuit that operates on 19VDC to 20VDC.
I am looking for a way to protect the circuit if 120VAC is accidently applied to the DC voltage inputs.
Resettable fuses (PTC's) protect against over current......
MOV's protect against short impluse voltage trasnients....
Is there a simple device(s) out there that will protect the circuit from a continous 120VAC input?

Anyone have any ideas for me?

Thanks
John Ahl - Milwaukee

 

A crowbar circuit might be suitable. It is widely used for overvoltage protection in DC supplies. I am not sure if it would work with AC voltage though, maybe it is necessary to replace the SCR with a TRIAC.

Anyone have any experience on AC crowbar circuit?

 

hi,

the cheapest i can think of is by using an input terminal of different configuration like a 3 prong socket with a slot guide. i usually do that for special equipments.

moz