[sdiy] Dual DC-Power from a single AC-supply

[Paul Schreiber]

>> And I did it with only 3 discrete diodes.
>>
>
> Hi Paul,
>
> Did your rectifier had fullwave rectification? That's the big difference 
> to the normal voltage multipliers. Do you mind sketching the rectifier. 
> I'm interesting to see how you did it.
>

No, it's 1/2 wave but the raw DC was fed into a pair of LM78L12/LM79L12 
regulators that have very high ripple rejection so it did not matter. You 
"pay" by having bigger caps on the front end, but in today's low ESR 105C 
caps about 330uf is all you need to draw 100ma or so (and 100ma will drive a 
LOT of op amps!). The ripple voltage is proportional to the load current, on 
a scope it can look 'rather nasty' on the input to the regulators. Don't 
know where the schematic is, it's around in a box somewhere :) I used it on 
4-5 different designs, just Google 'voltage doublers circuit'. As I recall I 
got the idea from a National Semi app note.

Paul S.