Black Top

All tube high voltage octave up

Black Top Schematic

High voltage all tube clean-ish octave up using two preamp tubes and a single power transformer. It does not use any transformers or diodes in the signal path.

I was able to derive the high voltage and heater voltage from the single transformer by using what I call the "Split Primary" trick. Many lower secondary voltage transformers come with two independent primaries. The idea being that one can get 120v operation wiring both primaries in parallel or 240v operation wiring the primaries in series. Since both primaries run on the same core the input AC on one primary will appear on the other primary which can then be rectified and used as high voltage. The secondary can be used for heaters. I chose a 12v secondary because it is easy to get.

The one down side to this trick is that you are only putting in half the energy into the core so you will only get half the current on the secondary. To compensate you will need a transform with double the current rating hence the 12v 600mA spec on my transformer.

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Your Tone God,