• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

My First Power Supply

Here is a PSU for Valve Amplifiers, 12V<+B<600V
Choose R204 to flow about 5mA through the LM385 2.5 (Common Zenner are very noissy) R206,R207,R208 to flow 5mA through the opto coupler and have 5V at pin 1, R209,R210,P201 to flow 1mA
The time constant R204*C207 (Aprox 10s) is made smaller than filament delay (Aprox 30s) this acts as a soft start
Output Voltage is given by

+B = Vreff * ( P201+R209+R210 ) / P201

For TL431 Vreff = 2.5V

The second circuit is a time delay for heating the Valves Before +B is applied



  • PSU1.pdf
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