Option to high cost Tube amp power transformers use a Voltage doubler D-lab test circuit & demo



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This is something I always wanted to try. Take a power transformer not intended for a tube amp, boost the HV to run one! I have read articles on line that the circuit could not supply enough current for a tube output section. Well here it is. The power transformer came out of a piece of military test equipment (641-061A). 120/240vac primary, Secs: 115V, 7V, 60V, 60V. I built a voltage doubler circuit for the 115v, which stepped it up to 295vdc. Note: you have to ensure the voltage double caps are rated high enough for the application. After doubling and rectifying, that 115vac turns in almost 300vdc! I used [email protected] caps for the design. Tested it under load using a 10K 20watt resistor before integrating it into the amp. It hung right in there around 295vdc @ 30ma draw. The really cool thing about using this circuit is, the output is rectified and filtered, so you simply connect it to your tube, no additional Plate filtering required! See schematic for details. The rest of the amp is my cookie cutter design with the heart being an ECB-AT board. It turned out to be a very quiet amp, little to no hum noted. If you scout around on ebay these type transformers show up for cheap! Of course, finding this exact transformer may be a stretch, You may substitute, but the concept works just fine! Lets keep the tube amp hobby alive!
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Audio
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