I built mine based of your schematics.
I only have a TL072 and a LM741 op amps. Not the CAblah blah blah.
So I used those. The video works fine. But the motor servo is not workin period. If I disconnect the reference signal, it slows down to whatever I have the pot set at. As soon as I connect the reference signal, zrrrrroooommm. full speed.
My disc isnt 12 inches, its more like 6 to 8 inches (ran off a computer).
But If I get the disc to speed and scan normally by manual braking, the pulses on the scope look exact same compared to the reference signal, so I know thats not the issue. The servo isnt doing the job. The comparator isnt working, its like its adding the phases, not subtracting them.
Both the reference and fork pulses are positive. Isnt one of them supposed to be inverted? or not.
Isnt it supposed to find the difference between the two phases, and generate an offset voltage? or not. I dont know how PLL works, so bare with me. If it has to find the difference, then one of the signals MUST be inverted, or oscillation will occur? both signals are positive.