We found this circuit that converts a direct voltage into a proportional frequency signal. The circuit is from an Electronics Now from April 1993. The JFET can be of any type.
This circuit was found in a 1973 publication. The SCR may be the TIC106 and must use a heat sink,...
This circuit is from the time when slide projects were used. We find it in a 90's Wels’ Think...
This circuit was found in a Radio Electronics Constructor, English magazine of April 1976; The...