This circuit, which can use the 4011 or 4001, was found in documentation from the 90s. The load depends on the transistor used, and the power supply must be isolated.
Disabling this circuit from a 2002 documentation can only be done by pressing 4 keys in a correct...
This circuit was found in a 1979 magazine. We can use any JFET like MPF102 or BF245. The relay is 12 V...
This circuit was obtained in a 90’s documentation. The operational amplifiers are from that time....