[invertedflight]

Does anyone know where I can get some really cheap optical encoder wheels to play with? I just want to built some simple circuitry using an optical encoder.
I tried using the guts from a computer mouse but after taking it apart you're confronted with the mechanical challenge of mounting the wheels, led's and receivers on your circuit board (and getting them lined up just right). Something that comes in it's own little package with a turnable shaft and a few wires coming out would be best.
Everything I've seen online so far is really expensive; I'd think there must be someplace to be a computer mouse-like setup for a couple bucks.

Thanks for any ideas!
Chris Hansen

[Bloy2004]

Here's an encoder that just ended on Ebay...item No. 7507259646. There are more offered by searching "encoder". I'm just wondering if this is what you had in mind, and if the price is right.

Bloy

[2muchstuff]

Hi, I noticed where you are from and I may have a source for you. A while back I traded some stuff at a hobby shop near you, Slot and Wing, northeast corner of Prospect and Hwy 72. I hope that's right, it's been a while. There was a bunch of servo motors and I think some may have encoders on them.There was a section in front of the counter that had a bunch of stuff that were odds and ends, that is where he kept them. Who knows I may have more at home but I'm 200 miles southwest from there. Good luck.

[invertedflight]

Bloy,

That's just about what I'm looking for. I'll keep an eye out on ebay.


2muchstuff,

Yup, I've been there. But every hobby servo I've seen uses a potentiometer on the output shaft.

[2muchstuff]

NO,NO,NO These are NOT hobby servos

[owhite]

http://www.usdigital.com/products/e3/index.shtml

$50.

owen

[JFettig]

I have been watching ebay quite a bit finding good stuff from time to time,
search "renco" theres a guy who sells trays of these, theres a tray of 5 for like $100 on there right now I think. the only thing I dont like is the shaft size, I dont think it would be a problem to make a bushing to fit the right size.

Jon

[2muchstuff]

I found another box of servo motors in the basement, these are the ones that I was talking about. I checked them out: Japan Servo Co., Type:dS48BT25-2, P/N:127K3190, 6.4 V/KRPM. They have a 2 wire tach on the back end of them. Sorry about that.

[H500]

Use an optical mouse. It has no moving parts.

[invertedflight]

How do I connect a rotating shaft to an optical mouse?

[H500]

Attach a disc to the shaft and mount the mouse sensor about 1mm from it. Alternatively, paint the shaft and sense it directly. It depends on your rpm.

[Bloy2004]

NO,NO,NO These are NOT hobby servos

Hi 2muchstuff,

I'm not sure what you mean. Could you elaborate? There's still a lot of wetness behind my ears ...

Bloy

[kong]

I think he means they are not servos, like the ones used to control a radio controlled car.

[2muchstuff]

Bloy2004,
Kong hit the nail one the head. Invertedflight had thought there were only the radio control type of servos there, but there are also these Japan Servo motors there. They are about 1 7/8" in diameter, 4" long and have a brass 16 tooth gear on the shaft.

Invertedflight,
I also remember trading some other servo motors, P/N: ME-3515-131E. I left the optical wheel encoders on some of the motors. Here is a link to what they look like, http://www.cmccontrols.com/downloads...atform3500.pdf

[Mat-C]

An optical mouse isn't going to work, at all. They have little cameras that watch the mousemat going past, and calculate movement from that. Extremely hard to make it work with a shaft, extremely hard to interface to (they are probably single chip solutions that go from camera straight to USB), and worst of all they are impossible to calibrate and will drift significantly over very short intervals.

Got an inkjet or laser? Just print your own wheels out onto acetate then stick that onto thin transparent plastic. Make sure the pattern is big (eg 2mm ish) so that alignment is easy, and if you need more accuracy make the wheels bigger. Once it works you can make your finished CNC machine cut you some permanent ones out of Al or something

[Xerxes]

Got an inkjet or laser? Just print your own wheels out onto acetate then stick that onto thin transparent plastic. Make sure the pattern is big (eg 2mm ish) so that alignment is easy, and if you need more accuracy make the wheels bigger. Once it works you can make your finished CNC machine cut you some permanent ones out of Al or something

That works very well (but I use optical period width of about 0.14 mm). See the picture of my home made 500 line encoder.

http://www.students.tut.fi/~kontkant/tmp/enkooderi.jpg

The quadrature optical encoder module can be extracted from old HP inkjet printer.

[Mat-C]

Nice work, you can't even see the lines.
Another plan might be to use less lines and more detectors, inteference-style? (Bit like a vernier gauge). Would need good alignment on detectors though.

[H500]

An optical mouse isn't going to work, at all. They have little cameras that watch the mousemat going past, and calculate movement from that. Extremely hard to make it work with a shaft, extremely hard to interface to (they are probably single chip solutions that go from camera straight to USB), and worst of all they are impossible to calibrate and will drift significantly over very short intervals.

There are several versions of the chip, made by agilent. The bigger version can output a quadrature signal, like any other encoder.

I have the small version from a $10 logitech mouse. It uses a serial interface which is very easy to interface using a PIC or AVR.

It is not hard to make it read off a shaft. Just mount the sensor about 1mm from the shaft. The shaft will need to be painted since it does not work well off a metal finish)

I found that the accuracy is as claimed, 400 counts per inch. I don't know how good the repeatability is, or whether there's drift over time. I will need to do some measurements when I get a chance.

[abasir]

For pendant or MPG use, you can just use the mouse center wheel encoder... details on this thread http://www.cnczone.com/forums/showthread.php?t=51494

Just bear in mind that it's not suitable for high speed or continuous duty though... :wave:

[neilw20]

How do I connect a rotating shaft to an optical mouse?

SUPERGLUE (stripes onto the shaft)