This circuit was found in the magazine of radio amateurs 73 in a 90's edition. The components are current and the transistor is of general use.
This is the basic configuration of an operational amplifier sample & hold circuit. The FET and...
The integrated circuit 4136 consists of operational amplifiers of type 741 in the same enclosure and...
We find this circuit in a 1987 publication. It makes use of comparators constructed around the 741...