pulse width modulator questions

[Otsismi]

I'm looking to make a pickup winder with a dc motor, pulse width modulator for speed control, and a digital counter. Most individuals with this setup use a magnet and reed switch to activate the dry contact circuit in the counter. But the counter also has a PNP and NPN counting mode.

Is there a way to wire one of these modes to the PWM so that there is a direct link from the speed of the motor to the counter?

http://www.ebay.com/itm/131051324934?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=371019022503

http://i1210.photobucket.com/albums/cc415/SKT1985/d4.jpg

[PRR]

RPM is not a simple function of Voltage, Current, or pulse duty-cycle.

A lightly loaded DC motor can be roughly speed-controlled with Variable Voltage (can be linear or PWM).

If the motor is really oversize, so it hardly slows down at all under load, then yes you could just "count" with an egg-timer. 78.9 seconds and it's done. But if it slows 1% one run and 11% another run, you have 10% difference in turn-count and DCR, 20% difference in inductance, 10% difference (1.6 semitones) in resonant frequency. Might you have 10% load-drag? Can such variation be tolerated?

[Otsismi]

No. It's looking like the reed switch may be the best option?

[Mustachio]

Last year I was playing with arduino and found this thread on making a pickup winder. Maybe it will give you some idea's I believe he is using an optointerupter . I played with the code and had it running on my uno and displaying on an lcd looked good I just never hooked it up with a motor or opto circuit. Still on the list of things to make

here's the thread

http://forum.arduino.cc/index.php/topic,88000.0.html

Good luck and I hope to see your final build!

[PRR]

> reed switch may be the best option?

Reed and a cheap calculator.