Frank, It’s the amperage that’s varied by the rheostat. The first component that sees the DC voltage is the vibrator tube, and I have to imagine there’s a limit to what the little coil in there can take. Everything else in the coil test circuit is rated for a lot more.
I might try half wave rectification with a few diodes in series to waste some voltage. Half wave with the load of a small light bulb got the voltage down around 8.5V.
Thanks for your input, all ideas are appreciated!
Tom
