Encoder Help!

mhamen3

Hi Guys,

I'm new to the forum and was hoping to get a little help.

I want to build a very compact and very basic encoder. I do not need to know direction, it does not need fine resolution, I just need a high/low pulse output from it. I would think that 8 "pulses" (or switches from low to high or high to low) per revolution would be good enough. Can it be as simple as puting a disc with four cutouts between an IR emitter and an IR receiver with the receivers output tied to ground through a resistor and also connected to an I/O pin? Or is there more complex circuitry that needs to be involved to clean up the signal?

Thanks,

Marc

EDIT: I'm not sure if it matters but I wanted to mention that it isn't going to be used for position or anything, I just want to be able to find the RPM of a shaft.

erco

http://forums.parallax.com/showthread.php?121179-Reading-Quadrature-Encoders&highlight=optical%20encoder

This Hamamatsu sensor is cheap and has lots of internal circuitry & filtering that will make your life much easier.

http://www.junun.org/MarkIII/Info.jsp?item=48

kwinn

A led and photo transistor with a slotted disk or disk with holes around the perimeter will work fine for this. I have even used the teeth of a bicycle chain gear to measure speed and distance.

mhamen3

Thanks guys!

I think that Hamamatsu sensor will be perfect.

erco

Yikes, I'm finding that they are hard to find suddenly. If I find them, I will let you know ( I wanna stock up). Typically I get them cheapest from Junun, but they are backordered. Acroname has discontinued them, and they had a nice circuit which I can't find right now. Will advise.

http://www.acroname.com/robotics/parts/R64-P5587.html

mhamen3

Oh ok. Its no big deal. I do not need them quite yet. Theyre for a project im working on but i dont need to integrate them yet.

I really appreciate the help, erco.

Heres a link to my project if ya wanna check it out.
Oh ok. Its no big deal. I do not need them quite yet. Theyre for a project im working on but i dont need to integrate them yet.

I really appreciate the help, erco.

Heres a link to my project if ya wanna check it out.

http://www.lynxmotion.net/viewtopic.php?f=8&t=7256&start=0

erco

See http://www.seattlerobotics.org/encoder/200010/dead_reckoning_article.html for usage info. Pinout attached. Datasheet at http://www.junun.org/MarkIII/datasheets/P5587.pdf


Now let's find some!

erco

Uh-oh... here's Junun's reply to my inquiry...

>Sirs: I am trying to order several of these sensors but your site
>says backordered. Do you know if & when you will get them back in
>stock? Thanks,
>
>erco

Never - they were discontinued by the manufacturer years ago, and are now
unavailable. I'm only leaving the product page up for reference, so people who
bought them from me in the past can find the data sheet etc.

mhamen3

Dang, that's unfortunate. There must be something similar on the market, right? Or maybe some of these are still floating around on ebay.

erco

My new love affair with the Sharp IR distance-measuring sensors is also ill-timed, as they were discontinued recently. I better stock up on those from Junun, too. Maybe that's why Parallax discontinued them (plus they're half the price of a Ping sensor).

http://www.parallax.com/dl/docs/prod/acc/SharpGP2D12Snrs.pdf

erco

Curiously, Junun is also permanently out of another optical encoder sensor, see http://www.junun.org/MarkIII/Info.jsp?item=14 even though the website implies they are available.

Is there an optical sensor conspiracy afoot?

WHO is buying up all the sensors?
WHY are they being discontinued?
HOW can we carry on without equivalent replacements?
Will it be too late to foil WHOEVER'S nefarious plan when it becomes all too painfully clear?

mhamen3

Ah yes. I've got a few of these laying around at home somewhere; they are great sensors. Too bad they're discontinued. I've also seen that they have mini versions of these, too. Are these what are replacing them?