[Elecraft] Overvoltage Protector

[Paul Christensen]

Scott,

Great contribution.  Surprising how many switch-mode supplies do not include 
OVP.  AD5X created a similar circuit using a single high-peak-current 
transient suppressor:

http://www.radiodan.com/ad5x/images/Articles/VcondRevA.pdf

Paul, W9AC

----- Original Message ----- 
From: "Scott Ellington" <sdelling at facstaff.wisc.edu>
To: <elecraft at mailman.qth.net>
Sent: Friday, August 20, 2010 4:00 PM
Subject: [Elecraft] Overvoltage Protector


> Some power supplies, like the Samlex SEC 1235, have no built-in 
> overvoltage protection.  All regulated power supplies are capable of 
> producing much more than their normal output voltage if any one of a 
> number of things fails.  Linear supplies are particularly susceptible, 
> since the pass transistor can short.
>
> While Elecraft assures me that the K3 can survive an overvoltage with 
> minimal damage, I prefer to be on the safe side.   So I designed a crowbar 
> circuit, which can be used with any 12 V power supply up to 30A.  If the 
> voltage exceeds the trip point (14-16 V), it will short the power supply 
> output and, if necessary, blow a fuse.
>
>
> I haven't built this one yet, but a very similar one I built in 1984 
> worked fine.
>
> 73,
>
> Scott  K9MA
>
> Scott Ellington
> Madison, Wisconsin
> USA