3 A switched regulator (CB8859E)

Found in a 90s Popular Electronics, this circuit provides a current of 3 to 5 A depending on the transistor.

Timed Code Switch Alarm (CB18003E)
Disabling this circuit from a 2002 documentation can only be done by pressing 4 keys in a correct...
JFET Timer (CB12123E)
This circuit was found in a 1979 magazine. We can use any JFET like MPF102 or BF245. The relay is 12 V...
Gain 1000 Amplifier (CB8998E)
This circuit was obtained in a 90’s documentation. The operational amplifiers are from that time....