[PLUG-TALK] light sensor question

Brent Rieck bsr at spek.org
Tue Sep 6 16:48:03 PDT 2011


On Tue, Sep 6, 2011 at 12:50 PM, Aaron Burt <aaron at bavariati.org> wrote:
> On Tue, Sep 06, 2011 at 12:17:36PM -0700, Brent Rieck wrote:
>> I built a camera shutter speed tester yesterday morning using an
>> Arduino and a photoresistor (and a few other things) - and it works -
>
> That's really cool!  Did you use a "real" Arduino, or one of the
> locally-made and USB-enabled Teensyduinos? (pjrc.com)

Thanks!  A friend and I have got lots of old cameras with shutters of
questionable accuracy and it seemed like a good tool to make.  I guess
it's a "real" Arduino it was a gift I got last year sometime that was
purchased from Sparkfun.  I hadn't seen those Teensyduinos before, I
like them though!

>> Digikey has many photodiodes that I see, is it a case of going through
>> one by one?  Or can I assume they're all high speed enough and it's
>> just down to package and wavelength sensitivity?
>
> They should all be fast enough.  Also look at phototransistors, Radio Shack
> has IR ones.  Finally, you can use LEDs as photodiodes, but they're slower.

Yeah, I finally figured out that I could look at the photodiodes on a
regular catalog page online which shows their response time in
nanoseconds in a nice big table to do easy comparison, I've not found
one that wouldn't be fast enough, I'll probably order a couple from
them this week unless I can find a local and convenient source.  Radio
Shack in North Portland had nothing useful, I'm not expecting the
others to be much better and I hate driving all over town.  Is there
another place in Portland that sells parts like that?  Or another
person who wouldn't mind meeting for a beer to sell said part?

> I think I have a couple phototransisitors in my parts box.
>
> If you want to order some, there's usually a Mouser or Digi-Key order
> through Dorkbot, but I haven't heard about one this week.

I've been meaning to come to Dorkbot but never get around to it; at
work we made fighting robots which were run by arduinos and controlled
by people using Microsoft Kinects to gesture punches and movement to
them and somebody mentioned that we should take it to Dorkbot - is
that something we should do?

--Brent



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