[sdiy] Power Supply ???

[Joe Kramer]

Dear John,
    Thanks--that makes sense.  If hang the 18v and +/-9v regs off the
transformer, and the +/-5v regs off the 9v lines, that would take the heat
of the 5v regs.  Does this seem sound?

Regards,
Joe




John Blacet wrote:

> If the current draw on the 5V line is small, it would be better to sub
> regulate the 5V from the regulated +15V or +12V or whatever than trying
> to drop the 20V in a regulator. You can also use a smaller "L" type
> regulator for this if you need less than 25 mA or so. Another trick is
> to use a series resistor to drop some of the voltage pre reg. This works
> fine as long as the current draw is fairly consistent. You want a
> minimum of about 8V into a 5V reg.
>
> Naturally, you want to check the resistor and reg for heat.
>
> Regards,
> --/////--
> John Blacet
> Blacet Research
> http://www.blacet.com