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 is from an American documentation from the 90's. The SCR can be of any type and the...
We found this circuit in the March 1992 issue of Radio Electronics magazine. The circuit has a...
This circuit uses the 741 Operational Amplifier to drive two LEDs. The LEDs indicate the signal of...