I found this schematic online for this VCO (Voltage Controller oscillator) and was trying to derive an operating equation for it. I realized that your rise time of the output of the first op-amp is a function of your input, the comparator and some of the first resistances. But the discharge time is actually a function of the comparator's output and R3, this is independent of the input making the discharge time fixed. Can anyone confirm this?
Here is some of my work: