scavenging opto-isolators

- Telephony attachments, like modems and answering machines.

- Anything that uses some kind of door or slide that opens and is 'electronic'. (E.g. a CDROM player may use it to detect it's door being open or closed, while a magnetron is likely to use a mechanical switch for the same purpose)

But my 2 cents: scavenging optos is not such a good idea. Don't expect more than 1 or 2 in any given device. (Or find an isolated 128-input PC I/O card :-)

Keep in mind that the quality of optos rapidly declines (transfer ratio falls) when they get hot, as in desoldering.

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Kind regards,
Gerard Bok

Pretty much anything with a switch mode PSU - some PC PSU boxes use them, but not all.

Old computer mice are ideal. I've used them in several projects. The mechanical parts are usually the first to go, they're cheap, (Hell, free!) readily available, the slotted opto-switches can be used as regular opto-isolators, (Just remove the cct board from the mouse, and the slotted wheels) and work off a directly-TTL-compatible 5v. Oh, by the way, use a bit of duct-tape to shield the light-path from any ambient sources.

Mind you, I'm not saying that these beasties will have the characteristics of the 6N13 series you mentioned, just that I've found them useful in the past.

Cheers, Pete.

Thanks for the helpful replies.

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Ignorantly,
Allan Adler 
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.

Mice. Two couplers in each of them.

This is a little confusing! - the OP asked about opto-couplers, the number given corresponds to couplers but everyone is posting info on opto-interrupters????

Remove the slotted wheel, and you are left with a photo coupler. One infrared led facing a photo transistor in a small black housing, or something like it.

But realistically, one is far more likely to find junk with real optoisolators than they will mice that they have to make do with the optointerrupters.

I've found a handful of mice over the years, I've found plenty of things with real optcouplers.

VCRs (if they have a switching supply), and note VCRs may be one of the most common things to find, and that would be the source of optointerrupters before mice.

Telephone related products are likely the second most common thing to find. Cordless phones, modems, answering machines. Real optoisolators.

Someone mentioned switching supplies. I find "computer power supplies" just lying on the sidewalk far more than I'll find mice. Plus, tv sets are likely to have switching supplies at this point (just pull the board and bring it home to take apart). Switching supplies also seem common in inkjet printers (at least the ones that have internal supplies) and inkjet printers are far more common a find than mice.

The good thing about optoisolators are that they are so easy to spot, with their six pin DIPs. Rarely will anything else come in such a package, so one can just glance at a board and see whether there are any.

Michael

My mouse suggestion came from the fact that I have about 12 of them lying around. :) Your milage may vary.

I have an old mouse I couldn't bear to throw out, even though it didn't work and the piece that holds the ball in place got lost. I kept thinking that someday I'll learn something about it. It's a Hewlett-Packard with S/N (serial number) 50C5806 and P/N (part number?) 5183-9012 Rev A and M/N (duh?) MO15K. I couldn't find the screw to open it up and decided to resort to force it open with a screwdriver. Eventually, I saw a kind of cylinder bending and realized that that must be where the screw was housed. Then I remembered that someone here once told me to look under labels for hidden screws and, in fact, it was under the label with the information I quoted above.

The mouse has a kind of track wheel which I find works very well as a top. I removed the board, which automatically left the interrupter wheels behind. The opto-isolators are on the board. There are two of them. Also, 3 pushbutton switches, even though the mouse only has two buttons. There is a chip on which is written: EICI127400 EM01 D 9948

A google search for EICI127400 turns up some hits for it as a chip but I haven't found a data sheet yet. There is a component that might be some kind of inductor. It's shaped like a piece of Wonder Bread with a hole in the middle and has three prongs descending from the bottom, like the three on a voltage regulator. All the circuit layout is on the bottom of the board. I'm thinking of photocopying it just to see if it helps make sense of the device. There is also a 5 wired (black, green, blue, yellow, orange) cable that plugs into the board and which, at the other end, is the jack for the mouse port on the PC.

I don't want to ruin the parts with heat, so I'll see if I can think of a way to remove the optoisolators without heat. They look pretty accessible.

--
Ignorantly,
Allan Adler 
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.

Same difference. Alternative usage, perhaps, but essentially the same type of device.

Cheers, Pete.

Ditto. The lab where I work has LOTS of PC's and goes through mice quite regularly. I've collected many over the years.

Cheers, Pete.

You could get away with cutting out a section of the cct board around the optoisolator with a hacksaw, and soldering on to the tracks around it, but I've never had any problems with desoldering them.

Cheers, Pete.

As others suggest, look at modems.

If you don't need pin-compatible and can bear a bit larger footprint, look at floppy drives as other suggest. I'm currently working on a project that uses (abuses?) a 5.25" floppy drive, which I'm looking at right now, and there are 2 IR interrupters and 2 IR-sensitive diodes hanging loose by their wires (which will eventually be removed as not needed).

By the way, the motor that moves the heads in that drive (made by Panasonic for IBM) is a big, beautiful, Sankyo stepper. 1.8-degrees/step. I've never done a hobby project with a stepper but this nice motor has inspired me to do something with it.

Allan Adler wrote: (snip)

If the PCB is phenolic you could easily break it in such a way that you could get at the device you want to scavenge with a cutting tool, e.g. end-cutting needlenose. (I have a pair of "end-cutters" that I got in the Air Force in the

1960's and that I reserve for this very use.) Snip away at the PCB material until your device is free, its pins standing proud with nothing on any of them except a solder ball with pad and a bit of board. Grasp device firmly with one hand, heat solder with iron in the other hand, and when solder melts shake the device hard to throw off the PCB+pad. This works best only when pins are straight, not bent against the PCB. Done this operation zillions of times (with many different parts) over the past 40 years and it's now second nature!

If the PCB is glass then the job can be more difficult. I usually don't snip the board in this case. I have a variety of big soldering iron tips (most home-made) that heat multiple pins at once. Heat 'em all simultaneously until solder flows, then immediately WHACK the board against an immovable object to throw off the solder. This operation takes a lot of practice! Be careful not to lose the part you're trying to save; I've had some fly off the board when I whacked it, no prying necessary. And, of course, wear safety glasses (better, a face shield) when you fling molten solder. I got a burn on one eyeball from molten solder and it wasn't fun.

Fine in principle but unless the circuit is fully cased up the opto-interrupter can be prone to ambient light, while prototyping the light from fluorescents or CFLs can stop the circuit completely.

Been there, done that, too! Got a stern lecture from my doc about wearing safety gear. It's the sort of thing you only do once!

Cheers, Pete.

Hence my previous comment about using a tiny piece of duct tape over the gap to block out ambient light sources. Do try to keep up!

Cheers, Pete.