[Milsurplus] LV Supply...

[Rick Brashear]

I would like to ask a little advice about my low voltage supply.  I have 
a capable transformer with very good filtering capacitors and a high 
current diode bridge.  My problem is, the transformer puts out about 16 
vac and by the time I get it rectified and run through the filter 
capacitors I am facing about 22.5 no load dc volts.  I am using it for a 
few different projects and experiments one of which is to operate a 12 
volt dynamotor.  However, the supply is so sturdy (capable of 80 plus 
amps) that even with the load of the dynamotor the voltage is still too 
high, about 16.5 vdc.  I'm not sure as to the best method to reduce the 
voltage to prevent damage to any of the old 12 vdc stuff I want to use 
it with.  My possibilities are, among others I'm sure:

*    Use a variac in the primary of the transformer to decrease the line 
voltage.

*    Use high wattage zener diode regulation.

*    Use dropping resistors to attain the proper voltage (too much wattage)

*    Electronic regulation

Any and all help will be greatly appreciated. Thanks,
Rick