Can we have the details?  ie schematic?
Thanks, David

Lawrence Lile wrote:

> > why do you need the pic? cant you just use like a few capacitors, a
> > rectifier (or 4 diodes, depending) a LM317
> Been there, done that, got the T-shirt, wore it out, sold it to Goodwill.
> LM317's are simple, but they won't handle more than an amp, won't dial down
> to less than 1.2 volts, pots are hard to adjust in tiny increments, and
> LM317's are linear so they waste lots of power.  I've prolly built a dozen
> supplies with them.
>
> You won't get 5 amps out of an LM317 without a bunch of extra parts.
>
> I built a nice little bench supply with a PIC running a P-Channel pass
> transistor, threw in an inductor and a capacitor and two pushbutton inputs
> to the PIC.  The PIC senses output voltage, and turns the pass transistor on
> and off.  The two pushbutton inputs run the setpoint up and down.  A little
> digital panel meter serves as the interface, you just push the UP button if
> you want the voltage higher, etc.  None of the part values seemed to be very
> critical, worked pretty good first time with junk parts off my bench.
>
> Running behind a stable 24V power source it seems to give pretty good
> regulation and will provide lots of current if required, will dial down to
> less than .25 volts, and can be adjusted in micro-increments.  Used a 16F873
> so I could use the 10 bit A/D for lots of fine adjustment.
>
> Of course there are 1000 circuits using LM317's plus pass transistors.  I
> just wanted to build a switcher with a PIC in it, so I could slap a sticker
> on it saying "PIC INSIDE!"
>
> --Lawrence
>
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