What is the cheapest DC motor encoder design scheme?

dc motor encoder

No specific requirement, just a general design.
How to construct a cheap DC motor encoder in a rather simple manner?
Thanks

motor encoder

Hello,
Look inside a mechanical PC mouse, or take it appart.
Just a sloted wheel and a couple of ligth sensor arranged so as when one of them is illuminated the other has the light blocked. You can use such disposition to sense the cw or ccw rotation.
Hope this helps

3mm dc motor

jorgito said:

Hello,
Look inside a mechanical PC mouse, or take it appart.
Just a sloted wheel and a couple of ligth sensor arranged so as when one of them is illuminated the other has the light blocked. You can use such disposition to sense the cw or ccw rotation.
Hope this helps

Click to expand...

Hello jorgito,
I had tried this scheme but how to fasten the sloted wheel with shaft is a big problem. Do you have any suggestions?
Thanks

dc motor+encoder schema

Oooops!
I doubt about that what I'm going to say is new to you, but if it is only to test something, you could try to use some plastic tubing linking the motor shaft an the home made encoder. Anyway if you plan to use it for more serious work it could be better to eliminate the plastic axis from the mouse wheel, drill it in its center (I guess 2 to 3 mm) and insert in a custom made axis with the 2 to 3 mm external diameter in a end and more in the other end as you can fasten to the motor shaft. That is a very simple lathe work.
It remains the problem of how to align the optical sensors, but I think that you could fix it to the motor frame.
Please let me know what you think.
Best regards.

jorgito said:

drill it in its center (I guess 2 to 3 mm) and insert in a custom made axis with the 2 to 3 mm external diameter in a end and more in the other end as you can fasten to the motor shaft.

Click to expand...

I am surprised of your such quick reply!
But I am sorry I didnt catch what you mean about "more in the other end as you can fasten to the motor shaft". I cant imagine why larger diameter will do help to fastening to motor shaft. Could you explain it in more detail? A simple picture will be very appreciated.
Thanks again.[/b]

My cad program has crashed, I'll try to explain better......

My idea is to make some sort of adapter sleeve. A single axis with diferent external diameter in each end. The smaller diameter end is solid and intended to support the drilled sloted wheel. The bigger diameter end is hollow, and the interior diameter is slightly greater than the motor shaft.