This circuit was found in a 1975 documentation. Current general-purpose transistors can be used, and the power is supplied with relatively high voltage. The gain is 30 dB.
In this circuit, from a 1977 publication, we have the traditional version of a filter that rejects 1...
The integrated circuit used in this application is uncommon today. However, the basic...
This physical line servo control uses components that are not currently common. The circuit is from...