Flood alarm (CB7994E)

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

Discrete Precision Regulator (CB15719E)
The voltage regulator circuit described is highly accurate and uses discrete components...
WWV 10 MHz converter (CB9184E)
WWV is the standard frequency station of the United States government. This station broadcasts a...
Voltage Detector for Battery Chargers (CB6061E)
Based on a 555, this 80's American documentation circuit detects the voltage of a battery and can then...