From an input signal, and using an unusual current source, this circuit generates a ramp, that is, a voltage that grows linearly up to a certain value, and then falls.
This digital instrument input circuit was found in the September 1989 issue of Radio Electronics...
In this circuit of a 1970s publication, data from the coil to oscillate at the desired frequency...
This circuit is from an old Elektor using components that are not currently common. The circuit is...