This circuit was found in a 1924 Gernsback publication. The variable capacitors are dual. Listening is through a high-impedance phone.
120 degree lagged signals can be obtained with the simple configuration shown in the figure....
This circuit was obtained from an American publication from the 80's. We can use a BD136 instead...
This circuit can be powered from 4 to 12 V sources. Pin 6 is the positive supply. See more about...