Door buzzer or alarm (CB20492E)

This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose NPN.

Neon low voltage regulator (CB8670E)
Found in the 1969 neon lamp documentation, using neon lamps this circuit provides 18 V regulated...
Preselector with JFET (CB9170E)
This circuit was found in a Popular Electronics from the 90s. The circuit uses a general purpose...
Accented Metronome (CB5336E)
This circuit was found in an ancient American documentation. The transformer is the type used in...