Optical potentiometer (CB22159E)

This voltage-controlled potentiometer using an LDR was found in an English documentation. LDR is common and LED of any type.

Wien Bridge Oscillator MC1776 (CB4498E)
The integrated circuit used in this project is not common today, but it can be implemented with more...
Digital signal isolator (CB8021E)
Found in an American publication from 1969, this circuit can be adapted to be used as a shield....
Ammeter (CB9660E)
This current meter with many scales was found in a 80s American documentation. The operational amplifier...