This circuit converts a high voltage into a frequency using an optical coupler. The transistor can be 2N2646 and the coupler admits equivalent. The circuit is from a 1974 publication.
This receiver was found in an American documentation from the 60's. The circuit uses germanium...
We found this circuit in the Texas Instruments' Linear Circuits Applications. It uses an...
The values of R and C are set so that a time constant of the same order of magnitude as the...