ODP: Right Transformer for 12v ?

[Roman Sowa]

half wave rectifier plus cap gives 12rms * sqrt(2) which is 17V at no
load
deduct some dropout in transformer, and always-too-small cap, diode
voltage, and you get 14-15V

standard doubler?
make two half-wave rectifiers with caps.
one for positive, another for negative voltage
(AC-top to anode1, cathode1 to cap1+, cap1- to AC-bottom.
AC-top to cathode2, anode2 to cap2-, cap2+ to AC-bottom)
between capacitors is doubled voltage (from cap2- to cap1+)

hope this description was clear...

Roman


> -----Oryginalna wiadomość-----
> Od:	KA4HJH [SMTP:ka4hjh at gte.net]
> Wysłano:	9 września 1998 06:27
> Do:	synth-diy at mailhost.bpa.nl
> Temat:	Re: Right Transformer for 12v ?
> 
> 
> What is "the standard voltage doubler configuration" for a bipolar
> supply
> from an untapped AC source? Simple half-wave rectification will give
> an
> unfiltered voltage less than 12Vrms x .707 (1/2 the square root of 2),
> which is obviously way too low. This is why I grab all the 15V+ AC
> wall
> warts I can. Voltage-doubling would be a big help. A somewhat
> underloaded
> 12v AC supply would just be sufficient for +/-12V DC.
> 
> Terry Bowman, KA4HJH
> "The Mac Doctor"