This is the way i aslo assumed things to work but......

My genius netmouse pro had only one pickup on each encoder wheel.   i too
out the encoder when and moved the tip of a pen through the gap and it still
picked up motion in the correct direction. Seems like the transistor theyre
picking the data up from is not all that standard. Maybe its some sort of
direction sensitive jobbie that can work on a very small angle.

John

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Paul B. Webster VK2BZC
> Sent: 25 December 1999 10:51
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [ot]Rotary Encoders
>
>
> Andreas Pockberger wrote:
>
> > The trick is that there are two sensors for each wheel so you will get
> > 2 impulsstreams out of one wheel the phases are 90 degrees shifted
>
>                                  |  Reading point
>                                  V
>              ___     ___     ___     ___     ___     ___     ___     _
> Stream A|___|   |___|   |___|   |___|   |___|   |___|   |___|   |___|
>            ___     ___     ___     ___     ___     ___     ___     ___
> Stream B__|   |___|   |___|   |___|   |___|   |___|   |___|   |___|
>
>
>