DPRG mailing list archives: [DPRG] Encoders

Fri Sep 7 22:18:11 CDT 2001

Three terminals?  That is what I saw in mine, I assumed power, ground and
signal, or base emitter collector.  Can't figure how they would get two
transistors with three terminals.  Unless it is two photodiodes with one
common connection.

Ed
----- Original Message -----
>From: "Sluggy!" <slugmusk at linuxlegend.com>
To: "Ed Okerson" <eokerson at fw.telenic.net>
Sent: Friday, September 07, 2001 10:09 PM
Subject: Re: [DPRG] Encoders

> Ed Okerson wrote:
>
> > OK,  I've opened up three different mice.  All of them only have only
one
> > led/phototransistor pair per encoder wheel.  I'm stumped.  How do they
know
> > which way the encoder is turning?
>
> The mice I've disassembled had a single LED and a three terminal
> detector that actually had two detectors in it. They seem to be a dual
> photo transistor or maybe photo diodes...
>
> Sluggy!
>
> --
>
>   ... because I'm a huge Beach Boys fan. I'll
>   never forget the first time I saw them in
>   person, back in 1964, at a fantastic concert
>   in New York... Wait, no, it was Philadelphia,
>   and it might have been 1967. And come to think
>   of it, it wasn't the Beach Boys; it was the
>   Bee Gees. Or maybe the Turtles. It was
>   definitely a plural name. Although, now that
>   I think of it, I'm not 100 percent sure I
>   was there.
>
>                                Dave Barry
>