This circuit was found in an American documentation from 1969. It serves to trigger circuits by providing a 7.5 V signal at the output from 500 mV pulses.
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....