06-17-2012, 01:47 PM
Speaking of lightbulb, you can use a DMM in series with lightbulb in series with primary, set on Amps. This way you don't have to rely on visual perception an will see the actual change in current. You can even ditch the lamp and leave the ammeter only, just use low voltage Variac setting and Amps and not milliamps on the DMM.