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.

Capacitor Test (CB4825E)
In this circuit the capacitor under test is charged at switch position A and then discharged...
Bicolor Kaleidoscope (CB4446E)
This LED light effects circuit is from 1988, but uses common components nowadays. The LEDs are...
Field Strength Meter (CB5189E)
This circuit can operate with signals from 1.5 to 150 MHz. C1 is 36 pF and C2 is 4n7. The diode...