Metal detector (CB7888E)

This circuit was found in a 1970s RCA publication. Transistors support modern equivalent types. Observe the dimensions of the explorer coil.

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Neon Lamp Drive with Silicon Switch (CB14706E)
This circuit is from the 1977 GE semiconductor manual. The components used are uncommon today....
Light or Heat Alarm (CB26234E)
This circuit has 4 operating modes and was found in the 1995 Encyclopedia of Electronic Circuits...
Lock Relay Using Diac (CB12993E)
The voltage of 30 V indicated in this project, shown in the figure, depends on the diac used. It...