Bass control (CB8722E)

Found in a 1993 Electronics Hobbyst Handbook, this passive circuit can be used with common preamplifiers and amplifiers.

Up to 3 minutes timer (CB21429E)
We found this circuit in a 1967 General Electric SCR manual. The time is set to R1 and depends on C1...
Electronic Fence (CB17136E)
This circuit uses an ignition coil to generate the high voltage that electrifies a fence. However, in...
Call Sound Amplifier (CB21273E)
Found in an older Radio Electronics, this circuit generates signals that can be used with regular...