VCO design based on the application notes of the LM538 datasheet. In order for the oscillation to start, since this simulator uses ideal op amps, we need to introduce a disturbance. That’s why we have that switch in the top. Sim must be started with the switch open, and then close it. A 1Hz voltage supply is our input, so we can see the output frequency vary as the input voltage changes. This VCO takes two inputs, the Control Voltage (Vc) in the first op amp stage and 1/2 Vc in the second stage. The two 1k resistors are a 1/2 voltage devider feeding the second stage.
2024/02/17
Added a phase comparator and turned it into a PLL. Output stage is a non-inverter opamp config used to provide voltage buffer and some signal boost, driving a first order low-pass filter to get a DC-ish signal proportional to the input frequency. Works for an input range of 10Hz - 200Hz
