6AC7 Amplifier (T450E)

Obtained in MIT documentation, this 4-stage circuit has high gain for small signals. The power supply sources 150 V.

Heterodyne frequency meter (CB21564E)
This circuit was found in a book on transistors from 1954. It works by the beat that is detected by...
Direct Coupling Stage (CB4680E)
This stage for general purpose transistors was taken from an old technical manual. The circuit can...
Reversal polarity protector (CB21581E)
This circuit provides reverse power polarity protection using a power MOSFET and a diode. The...