Flood alarm (CB7994E)

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

Resistance to voltage converter (CB5092E)
We found this circuit in an American 80's documentation. The circuit can be adapted to function as a...
Door Open Alarm (CB6367E)
This 80's circuit, suggested in Texas Insrtruments documentation, uses a Hall effect sensor. The...
Pulse and Ramp Generator XR2206 (CB24510E)
This interesting benchtop circuit was found in the May 1977 issue of Radio Electronics magazine. The...