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

Martin Peach martin.peach at sympatico.ca
Wed Apr 27 16:37:22 CEST 2011


Hi Pierre,
You can use any pot from about 1kOhm to 10kOhm. Less than 1kOhm will 
waste power and more than 10kOhm will not be able to charge the 
integrating capacitor fast enough, however if you only have one analog 
input in use it's probably OK to use much larger values.
And you probably want a pot with a linear taper so the resistance 
changes by the same amount at each position. Audio taper is good for 
volume controls as the low resistance end is stretched out so you have 
more control at low levels. Most pots are linear.
I would use a 7.5V rechargeable battery. 9V are too small. Or a stack of 
4 AAs, depending how long you need it to last.

Martin

On 2011-04-26 17:28, Pierre Massat wrote:
> Hi,
> I just got my Uno in the mail today. It's so cool! I'm all excited.
> I've been searching their website for some basic info regarding he
> components i should use, but haven't found anything.
> Do you know if i could use just any pot? Or is there a specific value i
> should use? Also, can i use a battery for power?
> It seems like their tutorials are mainly about programming the boards,
> and not so much about interfacing them with the real world. And as of
> 2011 Tron is still just pure fiction, and guess what, i'm still plain real.
>
> Thank you all very much for your advice!
>
> Pierre
>
> 2011/4/16 Martin Peach <martin.peach at sympatico.ca
> <mailto:martin.peach at sympatico.ca>>
>
>     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
>     <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
>
>




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