AC voltage probe (CB8185E)

This circuit for voltages up to about 20 V was found in a 90s Popular Electronics. The LED can be of any type or color.

Null Detector Circuit (CB25894E)
This circuit for measuring bridges was found in the October 1995 issue of Electronics Now...
Transistor Amplifier (CB18905E)
This excellent circuit came out in a Japanese publication from 1971. It uses Japanese transistors of the...
CW practice oscillator (CB7316E)
This circuit is from American documentation from the 90s. The configuration is very current and can...