[Elecraft] Power Supply (WAS: New amp)
Ron D'Eau Claire
rondec at easystreet.com
Thu Aug 18 18:28:30 EDT 2005
Tom wrote:
one thing I think which may have been missed, or at least glossed over, is
the fact the Astron supplies include a very good FOLDBACK CURRENT LIMITING
circuit which, if directly shorted (e.g. HOT lead directly to GND) will
instantly reduce the output current (and the voltage) to nearly zero with
little or no damage to the supply, the attached equipment, OR to the
cabling (or user).
---------------------------------------------------
Quite true, Tom. And that's why I said one must be careful with a
high-current supply. It's a lot harder to trip that crowbar circuit on a big
supply!
As I pointed out, a 13.8 volt, 50 amp supply will deliver full current into
a 0.3 ohm load WITHOUT OVERLOADING! That's 690 watts that can cause a lot of
heat in short order, and it won't even trip the crowbar.
Where I've found some ops get a nasty surprise is that they've become used
to seeing the crowbar kill the output when they accidentally short out a 5
or 10 amp supply, but when they do that with a bit of solder or wire on a 50
amp circuit, they're met with a face full of molten copper, solder or
whatever it was that got across the circuit and the power supply barely
hums...
Ron AC7AC
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