wallwarts and regulation..

[Ingo Debus]

Jay Martin wrote:
>  When dealing with AC the voltage is generally measured as the
> RMS value.  Therefore a 10v secondary would actually be putting out a
> 14.14v peak voltage.

Don't forget the voltage drop across the rectifier diodes. If there is a
four diode full-wave rectifier, this is at least 1.4 volts, so you have
only 13.7 volts left. (And you are still assuming the mains voltage is
sinusoidal. This is not always the case.) A 7812 has a dropout voltage
of 2 volts (@ 1A). So it may work, but it's not worst case design.

Ingo