On Tue, Feb 14, 2006 at 11:01:56PM -0800, William Chops Westfield wrote:
> On Feb 14, 2006, at 7:32 PM, Peter Todd wrote:
> 
> > I built a linear power supply using a 28A 6.3V transformer
> > from digikey. 237-1255-ND. 4x LM396K 10A regulators in
> > parallel through load-sharing resistors regulate the voltage.
> 
> What kind of filter caps have you got in there?  IIRC, you need
> pretty big filter caps in big linear supplies, and that in turn
> requires some sort of surge prevention to handle the turn-on
> case where the cap acts as a dead short.

As mentioned in another post, 100000uF, no surge prevention.

> And what kind of heatsink for the bridge?  At 28A, it's going
> to need to dissipate a goodly amount of power.  I've always
> found it a bit mind boggling that one of the most heatsinked
> elements of modern power supplies is the rectifier diode (more
> so than the regulating element, frequently), but the math shows
> it needs it...

I worried about that too, and very securely soldered the heatsink tabs
to my PCB. That said, I felt the diodes immediately after they fried,
and they were only a litle above room temp. Don't think that was the
cause.

-- 
pete@petertodd.ca http://www.petertodd.ca
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