Permanent magnet detector (CB22463E)

We found this circuit in Popular Electronics from 1992. Transistors admit equivalents.

Residential Lock and Alarm (CB18669E)
This encoded lock circuit with alarm for use in homes was found in a publication from the 90s. The...
Temperature Sensor (CB14135E)
The circuit shown was found in the 1994 National Semiconductor Linear Applications Handbook. The...
FET timer (CB12500E)
This circuit is from a 1979 documentation. The FET can be the BF245 or MPF102 and the bipolar...