Kinescope Rejuvenator (T464E)

This utility circuit for old TV restorers was found in a Popular Electronics from November 1968.

Equivalent circuit LM381 (CB25270E)
The figure shows the equivalent circuit for the LM381 audio preamplifier IC. The circuit was found...
Gain Operational Amplifier (CB11614E)
The gain of the operational amplifier shown in the figure depends on the feedback resistor,...
Motion Doppler Sensor (CB8763E)
This circuit was found in a 90s Popular Electronics. The sensors can be common speakers that reach...