On 06-Feb-02 John Walshe wrote:
> Hi guys'n'gals,
>     Has anyone got any neat ideas on how to a +5v to -5V converter for a
> power supply. Only a few milliamps required on each rail. It's a once off
> for something I'm trying at home. I did try just splitting the supply but
> for some reason the positive circuit didn't like it (it wouldn't work!).
> I must invest in a dual rail PSU sometime!
> Any thoughts appreciated,
> John

Charge Pump !

generate a square wave signal 0 to +5v

Put it throught a capacitor  (say 1uF)

Connect other end of capacitor to a diode which has it's cathode connected to
0V.  You will get -4.4v  (5v - diode drop) on the capacitor.

Or get a charge pump IC which does it all for you (MAXIM do such devices, but
I've never used any so I can't recomend a particular device).


Hope this helps.

Peter

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