Overvoltage Indicator (CB22007E)

Using a CA3130 operational amplifier, this circuit drives an LED when the voltage exceeds the value set in VR1.

VCR Amplifier (CB25269E)
This circuit for VCR recording heads was found in the February 1990 issue of Radio Electronics magazine....
Simple continuity tester (CB7955E)
This very simple continuity tester uses a small 1.5 V lamp (type used in flashlights). Can be...
Transistor Radio TR3B (CB18388E)
This commercial radio with 3 earphone listening transistors was manufactured in Japan in the...