This circuit was found in General Electric documentation from 1965. The transistors are from that time. The diodes consist of a component that contained them.
This digital instrument input circuit was found in the September 1989 issue of Radio Electronics...
Found in an Electronic Design of 1964, this circuit operates with control voltages from 0 to 12 V...
This two-way switch or control shows how to control a lamp from two points. This version is from a...