On 2011-04-16 07:09, Pierre Massat wrote:
Hi, I just ordered a Uno, i think it will suffice.
Martin, I'd like to replace my pot with an optical sensor if it's quieter. Only i've never used one. How does it work? How do i put this in the pedal?
I got a reflective sensor which consists of an IR LED and a photo transistor in one package, with both components facing in one direction like the Vishay TCRT5000L: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=751-103...
You put a 10 kOhm or so resistor to 5V on the collector of the transistor (bigger resistor = more sensitivity but adds noise) and a 330 Ohm resistor from 5V to the anode of the LED (smaller resistor = more sensitivity but don't burn out the LED), the other two pins to ground. Then connect the transistor collector to an arduino analog in.
Mechanically, mount the device so it's looking up at the underside of the pedal and adjust things until you get a good range of values. It may help to stick some reflective material on the pedal, for greater sensing range.
These kinds of sensors are used a lot in printers to detect paper, so if you pull apart old printers that's one thing to look for, besides the motors.
Martin