5-tube 3W Amplifier (T478E)

This circuit was obtained from a 1947 amplifier manual. The circuit makes use of a transformer source, but it can also be battery powered.

| Clique na imagem para ampliar |

Wiretapping Transmitter (CB19320E)
This circuit was found in a 90's espionage publication and serves for analog lines. The circuit is...
Beat Oscillator (CB16896E)
This circuit is used in short wave receivers that do not have the BFO (Beat Frequency Oscillator) for...
Double Flasher 555 (CB20943E)
Found in Popular Electronics from the 1980s, this circuit shows how to drive two charges...