Post by Ty Unes
I have a power transformer with 6.3VAC filament voltage I want to use in a
circuit. Is there a way to mix 6V and 12V tubes powered from this
transformer? In other words, can I power 2 6V tubes and then double the
voltage somehow to heat a single 12V tube? If so, I'm having trouble
visualizing how to do this.
Voltage doubler of 2 diodes 1N400x and two capacitors: 1000uF/16V (input)
and 470uF/25V (output) will work. 25V rated cap is required for safe
operation if the valve is not plugged in. A dropping resistor will be
needed, most likely. It is better to connect it at the input to the doubler,
not the output. In this case voltage waveform will be less distorted and
less magnetic harmonic hum generated from the transformer. It is important
to connect return wires from one of the diodes and a capacitor to a terminal
of the transformer, not just to the chassis anywhere (if one end of the
transformer 6.3V winding is grounded). It will reduce conducted hum.