[sdiy] power-question

[Scott Bernardi]

The 18v is an AC rating - like an RMS vale. The peak value will be 1.414
times that - 25.45 volts. Also, the AC rating is at the rated load
current, and so will be higher for lighter loads. The filtered DC
voltage going into the regulator will be approximately the peak voltage
minus a volt or so.
For +/- 15v power supplies, a 25.2VCT transformer is a good choice.

ulrich kehrer wrote:
> 
> hi!
> 
> a power supply problem...
> 
> i have a 2x18V/2.22A tansformer and after the bridge rectifier i get +/-
> 28V thus my +/-15V regulators get really hot (i know that the input of
> the regulator should only be 3V higher than its output)
> i suppose the 28V are not normal, are they?
> 
> (the rectifier is a 50V/6A one; i replaced it with 4 1N4005 diodes but
> that didn't change anything)
> 
> any help concerning the +/-28V is really appreciated.
> 
> regards,
> ulrich

-- 
Scott Bernardi
sbernardi at home.net