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 circuit was found in a. transistor Manual from 1958. This is an amplifier stage with a...
Another of the many similar configurations we have in this section. This one is from a Radio...
We found this circuit in a Radio Electronics from October 1965. The pickup coil can be of the...