instrumental
New Member
Hello. I am using salvaged HDD motor as a sine wave source and I'm feeding those signals into LM324N using schematic in attachment. Basically, idea is to spin the motor, motor generates sine signals, comparator converts them into square and then I'm feeding the signals into microcontroller, to read input data. Original schematic suggested 1k resistor for R1 and R3, and 10k for R2 and R4, but that didn't gave me good enough resolution from the disk - I had to spin it faster to detect signal change. So I'm using 100/22k combination, which works exactly like I want it. Now, obviously, I can't get infinite signal gain, so what I'm asking is, what resistor combination would result in maximum gain in this specific scenario? I even tried to switch 100ohm resistors with 47ohm, just to see what happens, but nothing changed. I'm really lost on op-amps and comparators, so if anyone has good literature/video/links to suggest, I would be grateful.