[PD] Arduino, any feedback to help me choose the model?

[Martin Peach]

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=751-1034-5-ND

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