Metal Detector (CB21929E)

This two-transistor metal finder was found in a Raytheon manual from the 1950s. The transistors are germanium from the time.

Voltage Doubler (CB17076E)
This simple voltage doubler provides a continuous voltage at its output that is twice the peak...
Emergency light (CB7044E)
This circuit was obtained in an old Elektor and can be adapted to use white power LEDs. The...
Microphone Preamplifier (CB15118E)
This circuit was obtained in an Argentine publication from 1973. The original version uses...