philpem’s blog

I think I’m on a “make it smaller” bent again. I’ve ended up building a laser tachometer to assist in testing the motor speed controller code (which is going to end up using a PID loop for speed control, more later). After I finished it, I realised that I’d ended up designing what effectively amounted [...]

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If you’re just here for the answer to the question “how fast does the Ptouch motor need to run”, the answer is 3000RPM. Ish. I’ve confirmed this using two different measuring methods — measuring the timing between noise spikes on the motor’s power lines, and the old reflective-tape-and-laser trick. I didn’t use the motor inside [...]

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