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Re: [TenTec] Need advice about OVP for 262G

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Need advice about OVP for 262G
From: Tim Long <tlong8@earthlink.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 01 Apr 2009 10:17:16 -0400
List-post: <mailto:tentec@contesting.com>
Hello Curt,
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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