Optical shield (CB20698E)

This circuit was found in American documentation from the 90s. The coupler is the type that uses a photo-Darlington.

1 kHz Notch Filter with the 741 (CB12287E)
In this circuit, from a 1977 publication, we have the traditional version of a filter that rejects 1...
Voltage Controlled Current Source 3900 (CB19706E)
The integrated circuit used in this application is uncommon today. However, the basic...
Servo Control (CB5941E)
This physical line servo control uses components that are not currently common. The circuit is from...