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Author Topic: Using an encoder wheel from a mouse  (Read 4892 times)

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Offline h_manTopic starter

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Using an encoder wheel from a mouse
« on: October 04, 2007, 04:15:09 AM »
Hi,

Recently I have been experimenting with 2 different sets of IR sensors and have been frustrated by the following problems:

Taking the IR emitter/detector pair from a microsoft mouse I am able to power them up and count pulses using the suggeted resistor values on the society of robots webpage (ie, 120 Ohm for the emitter and 11KOhm for the detector). However, in a microsoft mouse the IR detectors only have 3 pins. And therefore from my understanding there is only one output. My assumption is that I must be doing something wrong as there surely must be 2 sensors inside?? (in order to detect motion forward & backward)

With Logitech mice, the detectors have 4 pins, 2 of which are outputs. My problem however is that I cannot seem to choose the right resistors to activate them when they are removed from the mouse circuit board.

If I had the datasheets for these components it would not be a problem. Has anybody reading this overcome these problems?

Please help ???

Harry

Offline paulstreats

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Re: Using an encoder wheel from a mouse
« Reply #1 on: October 04, 2007, 01:58:32 PM »
Quote
in a microsoft mouse the IR detectors only have 3 pins

maybe there are two detectors, just 1 pin  is for +v to both sensors and the other pins (1 from each detector) go to ground maybe through external transistors

ie.
      |-------------------------------gnd
(detector)
      |
      |-------------------------------+v
      |
(detector)
      |--------------------------------gnd

Offline h_manTopic starter

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Re: Using an encoder wheel from a mouse
« Reply #2 on: October 05, 2007, 08:08:08 AM »
Thanks, that was spot on. I tried reversing the connections and having what I thought was the gnd as my output and vice versa and I got a signal from this (as well of course as the other way round).

I now go to scratch my head about how to connect them up so that I can use both detectors simultaneously.

Cheers..  :)

Offline _Rahul_

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Re: Using an encoder wheel from a mouse
« Reply #3 on: October 07, 2007, 09:06:09 AM »
are you using the sensors of a mouse to count the signals from the detector?

Buddy, can u help me with that ?
I mean I want to make a counter, that can count the signals. Can I use the old mouse for that ?

thanx!

rahul!!!
« Last Edit: October 07, 2007, 09:07:28 AM by _Rahul_ »

Offline paulstreats

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Re: Using an encoder wheel from a mouse
« Reply #4 on: October 07, 2007, 11:43:22 AM »
the old style mice have an ir emitter, and 2 ir detectors. Between them there is a small encoder wheel which is basically just black spokes with gaps in between. when the wheel spins the ir light either is blocked by the spokes or travels through the gaps to the detectors

Offline h_manTopic starter

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Re: Using an encoder wheel from a mouse
« Reply #5 on: October 10, 2007, 07:32:52 AM »
Hi Rahul,

I am attaching the circuit I used after having received the hint from Paulstreats to use transistors. The resistor values used where both 10KOhm. The transistors where of type 2N3904...  (the pic is just how the detector is connected up)

Apologies for the poor illustration, I did it in paint.

Ummm.. Paul, or someone else, could I pick your brains again regarding advice on how to activate the Logitech mouse IR detector/emitter pair. I would much rather use them over the microsoft ones as they have twice as many holes.

Thanks,

Harry
« Last Edit: October 10, 2007, 07:35:22 AM by h_man »

 


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