Flood alarm (CB7994E)

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

Low cost isolation transformer (CB7973E)
Two identical transformers can be used as a single improvised isolation transformer. The maximum...
Community TV Transmitter (CB18132E)
This transmitter can send its signals from several kilometers away, depending only on the antenna...
Power control (CB23586E)
This circuit was found in Radio Electronics magazine from January 1959. The power transistor must...