Flood alarm (CB7994E)

This circuit is from a 90s Popular Electronics. The transistors are of general use and the buzzer is a Sonalert type.

Display brightness control (CB21614E)
Based on Allegro's A6275, this circuit controls the brightness of various displays. The circuit is valid...
AM Transmitter (CB513)
This small transmitter can act as a wireless microphone operating in the medium wave range,...
SCR dimmer (CB21652E)
This is the circuit of an RCA Dimmer sold in 1967. With it it is possible to control a load up to...