Telephone parts?

A 3x4 keyboard, if you need one, may be worth more than that but the one in the phone may be integrated into the PCB too much to be usable outside of the phone's body and its PCB. The entire phone is pretty much on one big IC these days so hard to tell if you can harvest many usable parts beyond the obvious cables and perhaps that keyboard. Do you need an electret mic? There's one in there as well as a (really bad quality) loudspeaker. There's probably a reed switch in there.

It's been more than 10 years since I've been inside an analog land line telephone set but I think it's safe to assume that the never ending miniaturization made the amount of re-usable parts in those phones pretty minimal by now.

brand new) for $ 2.50 each.

typical telephone parts include: microphone, loudspeaker, ringer, DTMF circuit, keypad, cable, modular jack, case

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The likely value of the parts goes up if you actually have need of something phone related. So if you needed a touchtone pad, you might be able to get that function out of it (once upon a time, that sort of thing was common, by now with most phones doing touchtone, there's a lot less need). It won't even be good as an interface to the phone line, since it likely has no isolation (counting on the circuit being used without external conenctions and just as the IC manufacturer lays out the cicuit).

SOmething current is a lot less likely to be useful, as others have pointed out, because the integration is high.

If you're buying new things, then something like those 99cent FM radios would have a descendent of the TDA7000 FM receiver IC that had some use if you were building FM receivers. I've yet to see them, but legend has it that some low end AM radios use a descendent of the ZN414 TRF AM receiver IC that used to see a lot of projects. That sort of thing doesn't offer much by building it yourself, but it's a cheap and handy way to get the ICs.

If you're just looking for parts, go to garage and rummage sales, and buy used electronics that nobody wants and is thus cheap. Older cordless phones offer up way more parts than some cheap solid state phone, especially if you're interested in radio. VCRs will offer motors and endless small signal transistors and if it's old enough, transformers with multiple windings. Satellite boxes are common, the parts are limited but if the price is right. They often provide a nice cabinet. Anything that's cheap (and the older the better because it won't be so highly integrated) is likely to be better than buying something cheap and new off the shelf.

Or look for these things in the garbage. I brought home another cassette deck last week, I don't think it's any better than what I've found in the garbage before, so I'll likely strip it. It will offer up a power transformer (something that often costs real money when building something), some DC motors, endless small signal transistors, and if noth8ing else, an LED VU meter. I once needed an ac adapter for a Powerbook 1400C I got at a rumamge sale, and remembering for some reason that inkjet printers tend to have higher voltage supplies (I needed

24vdc), I opened one I'd brought home, and extracted a nice module to provide the needed power. Inkjets are also common, lots of mechanical parts (though not as many as dot-matrix printers) and likely enough parts if they are found in the garbage (and thus free) though with an IC controller they tend to be a tad too specific. They tend to have some power transistors.

That's the thing, some items are better than others for certain parts.

Michael

Ivan Vegvary was thinking very hard :

Plug it in and use it. Emergency use when cell towers go down or power goes out. Send me a couple.

I just bought a Panasonic DECT wireless phone with a standard phone base station so I have phone access when the power goes out.

brand new) for $ 2.50 each.

Thanks everyone for the great insight. I guess I'll be buying one of these phones just to see what's inside. All the comments about integration are excellent points that I had not considered.

Ivan Vegvary