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Telephone parts?

Discussion in 'Electronic Basics' started by Ivan Vegvary, Apr 22, 2013.

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  1. Ivan Vegvary

    Ivan Vegvary Guest

    One of the discounters in Portland is selling "slim-line" phones (land line, brand new) for $ 2.50 each.
    Is this a bargain for parts? Anything fun and usable inside?
    Ivan Vegvary
  2. Jasen Betts

    Jasen Betts Guest

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

    passerby Guest

    responding to ,
    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.
  4. 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

    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.

  5. BeeJ

    BeeJ Guest

    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.
  6. Ivan Vegvary

    Ivan Vegvary Guest

    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
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