[TCML] SRSG

[Dennis E. Bahr, P.E.]

When building a Phase controller for a SRSG I found that using a 2 
Amp 400 Hz variac works just as well as using a large 5 to 7 Amp 60Hz 
variac.  Since the variac is used as a variable inductor its normal 
operating frequency doesn't matter.  Typically, one wants something 
in the 2 Henry range or less.   Because of the higher frequency, the 
much smaller 400 Hz variac has about the same inductance as a much 
larger 60Hz variac.  With a 2 Amp General radio M2 and a 7.5uF 
capacitor I can get more than 45 degrees of control on a small 
Oriental synchronous motor.  The variac is useable over its entire 
rotary range with a maximum voltage rise of somewhere between 5% and 10%.

Dennis E. Bahr, P.E.