Kevin A. Benedict wrote:
>
> >From David Duffy
> >The 3 pin IR detector may be 2 IR detectors with a common lead?
> >Does the encoder have 2 sections - one 2 pin and the other 3 pin?
> >I'd think that it'd have to otherwise it couldn't detect the direction.
>
> I got a nice Infrared Picture of the phototransistor,
> and three other pictures of the mouse circuit, about
> 200kb all together.
> http://www.members.dca.net/kben/misc/mouse.html

> Any comments on interfacing the ir led and phototransistor
> to a PIC are welcome.


Hi Kevin, that IR sensor is a dual IR photodiode.
It has one common pin and two pins for the outputs
of the 2 separate IR diodes.

These are easy to interface to the PIC, you can run
the LED with a few mA, normally about 5mA, and connect
the IR diode(s) via a high value resistor to +5v.
Try about 56k to start. The IR diode is REVERSED.

When NOT illuminated the IR diodes have little leakage
and will act open circuit, so the voltage to the PIC
is a logic HI.

When illuminated with IR, the diode resistance drops
to a few k ohms, and the voltage to the PIC goes to
a logic LO.

Like this:
              a   k
 0v (gnd)------->|-------*----R1------- +5v
              IR diode   |    56k
                         |
                         |
                   output to PIC

-Roman
PS. Can you FIX your reply-to address!!!!

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