Over-Voltage Protection is normally done with a "crowbar" circuit.
There are several circuits but the gist is you have a comparator with a
very sharp knee that triggers an SCR. The SCR conducts the shorting
current and blows the fuse. I've seen circuits using a UJT and another
using a 723 voltage regulator. Mine uses a 723 voltage regulator. If I
can find the schematic, I'll scan it and send it to you.
73, Tim, W2UI
Hulett, Russell wrote:
> Hello Mike,
> As I read the datasheet for the 1.5KE15A, the breakdown voltage is nominally
> 15 VDC. So when the pass transistor shorts, won't the transient diode limit
> the voltage to the load to nominal 15 VDC, bypassing enough current to ground
> to trip the overload on the power supply?
> I intend to incorporate a fast-blow fuse, not sure why the question prompted
> the sarcasm.
> 73, Curt KB5JO
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