High Power Alarm (CB20475E)

We found this circuit in a Popular Electronics from the 90's. The circuit uses three SCRs to trigger the loads.

Logic Level Tester (CB4469E)
This circuit can use both separate LEDs and a common cathode display when one segment indicates...
Microphone Amplifier (CB12918E)
The first transformer is a driver found on transistor radios and the second a small output...
UJT Triangular Signal Generator (CB19509E)
Signals of up to a few tens of kilohertz can be generated by this circuit found in a European...