MIKE ROSS wrote in a message to Roy J. Tellason:

 MR> "Roy J. Tellason" wrote to "MIKE ROSS" (31 Oct
02  20:06:38)  ---
 MR> on the topic of "BATTERY PACKS"

 RJT> I scrapped out an old linear power supply board that was originally
 RJT> made by IBM,  who you'd think wouldn't tend to skimp on their
 RJT> components.  They had a crowbar circuit on there with an SCR in a
 RJT> TO-220 package that did _not_ use a heatsink.  That's pretty typical
 RJT> from what I've seen.

 MR> Those scr's are meant to vaporize the powersupply trace on the
 MR> circuit board and self-imolate to a crisp while doing it; 

Nonsense.  The design there included a _fuse_ for that purpose...

I've never seen a crowbar circuit that didn't include either a fuse or a
breaker in line with the power coming in.

 MR> a heatsink would be like adding window dressing. I've got a boxful 
 MR> of switchers with roasted crowbar scr's. Some boards are a real 
 MR> mess and look like they spent a long time in a toaster at the 
 MR> darkest setting. From time to time in a pinch I salvage the 
 MR> occasional Schottky rectifier in that box. 

Those cooked boards are a result of power semiconductors that ran too hot. 
I've got a few around like that as well.

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