Two-tone solar buzzer (CB20493E)

This circuit was found in a 1991 publication. The transistor can be a general-purpose type.

12 44 and 50 V regulated power supply (CB8680E)
This power source was found in a 1968 Electronics World. The transistors are from that time. The...
Residential Alarm (CB17527E)
This circuit was found in a 1986 documentation. The circuit uses 12 V relays and is powered by a...
144 to 146 MHz amplifier (CB19563E)
This circuit amplifies VHF signals in the two-meter range and is very critical, especially...