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.

Transistor Tester (CB10768E)
I found this circuit in a 1992 Electronics Experimenter Handbook. The circuit can be easily...
Power Switch (CB24697E)
This automatic switch for multiple loads was shown in the May 1983 issue of Radio Electronics...
Variable Frequency Oscillator (VFO) (CB4586E)
The Variable Frequency Oscillator (VFO) shown in the figure can generate signals in a frequency...