Figure 9-C Minimalist's Williamson Circuit. The hot input terminal goes through a 0.1 u f capacitor to pin 7, the grid of a triode which is labeled one half 12 eh X 7. The cathode, pin 8, goes to the top of a 5 k pot, P 1. The wiper is tied to the bottom and they go through a resistor to ground. The resistor is labeled capitol r, small k. The top of the pot also goes to the positive end of a 470 u f 25 V capacitor. The negative end goes to the junction of the lower end of the pot and the resistor. The grid also goes through a 1 meg ohm resistor to the junction of the pot and resistor in the cathode. The same junction goes to a point labeled G N F B which stands for global negative feedback. The plate, pin 6, goes through a 470 k ohm resistor to a point we will call B plus 2. The plate of the first triode also goes directly to the grid, pin 7, of the second triode one half 6DJ8. The cathode, pin 8, of this triode goes through a 47 k ohm 2 watt resistor to ground. The cathode also goes to a point labeled T P 1 which stands for test point 1. The plate, pin 6, goes through another 47 k ohm 1 watt resistor to B plus 2. The plate also goes through a 100 k ohm resistor to the junction of the pot and resistor in the cathode of the first triode. The plate also goes through a 0.1 u f capacitor to the grid, pin 2, of the top triode in a 6CG7. The cathode of the half 6DJ8 goes through another 0.1 u f capacitor to the grid of the lower triode, pin 7, of the 6CG7. B plus 2 connects through a 2.7 meg ohm resistor then through a 1 meg ohm resistor to ground. The grid of the upper triode, pin 2, goes through a 1 meg ohm resistor to the junction of the 2.7 meg and 1 meg ohm resistors. The lower grid, pin 7, goes through another 1 meg ohm resistor to the junction of the 2.7 meg and 1 meg ohm resistors. Both cathodes of the 6CG7, pins 3 and 8, are tied together and go to one end of a 5.6 k ohm 1 watt resistor. The other end goes to the drain of a depletion mode m o s f e t Type IXCP10M45S. The source of the m o s f e t goes through a 100 ohm resistor than a 500 ohm pot to ground. The wiper of the pot is also grounded. The pot is labeled P 2. The gate of the m o s f e t goes through a 1 k ohm resistor to ground. The plate of the upper triode, pin 1, goes through a 33 k ohm 2 watt resistor to plus 400 volts. The plate of the lower triode, pin 6, goes through another 33 k ohm 2 watt resistor to plus 400 volts. The plate of the lower triode goes to a point labeled T P 2. The plus 400 volt point goes to a point labeled T P 3. The plate of the upper 6CG7 triode, pin 1 goes through a 0.1 u f capacitor to output 1. The lower 6CG7 plate, pin 6, goes through another 0.1 u f capacitor to output 2. Output 1 goes through a 100 k ohm resistor to ground. Output 2 goes through another 100 k ohm resistor to ground. B plus 2 is bypassed to ground by a 100 u f 450 volt capacitor. A 1 k ohm resistor connects between B plus 2 and plus 400 volts. The plus 400 volt point is bypassed to ground by another 100 u f 450 volt capacitor. This completes the description of figure 9-C.
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