POWER SUPPLY: The high voltage supply is a half-wave voltage doubler circuit.
The low-voltage filament supply is a full wave circuit.
Note About The Schematic
Vacuum tubes require two power sources: a low-voltage, high-current supply for the filaments and a high-voltage low-current supply for the plates. From right to left, Figure 4 (above) shows how wall juice gets converted into tube food. The tall vertical lines represent the iron core of the power transformer. The primary coil on the right gets connected to "117 v / 60 ~" while the two secondary coils create 110 VAC Volts (of) Alternating Current and 22 VAC.
A pair of diodes RS-1 and RS-2 serve as a half-wave voltage doubler. Each rectifies half of the 110 VAC / 60Hz sine wave, turning it into about 265 volts direct current (DC), after which capacitors C9 and C7 smooth the humps into non-audible, filtered DC. C6A and C6B provide further filtering, while R8 serves as the voltage divider for the different stages of amplification. The "B Plus" voltages are ballpark and unregulated meaning that they will vary with the incoming line voltage and with tube condition. Only after the tubes are in and warmed up will the voltage at points "1" and "2" be approximately 235vdc and 155 vdc, respectively.
The 22VAC winding is rectified by RS-3. Unlike the half-wave voltage-doubler circuit for the plate supply, the two diodes that comprise RS-3 are configured for full-wave rectification. Since the winding is center-tapped, each diode rectifies an 11 VAC sine wave into a positive-going hump. When combined, the "two humps" effectively double the 60 Hz line to 120 Hz. (Thats why power supply failures generate 120 Hz "hum.")
Power Supply Notes:
High voltages can give a buzz that can end your lifetime. Use caution and remember that capacitors will retain their charge even after the power is turned off.
Yes, Phantom Power would be a great addition. In this case, it wouldn't even be necessary to build another supply. All you'd have to do is add a dropping resistor and a zener diode clamp, but I haven't worked that out yet...
Meanwhile, you have two options. Click below and you'll be there
in a flash.
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