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"Fuzzy" push button component

Discussion in 'General Electronics' started by Arne Harisson, Jan 31, 2004.

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  1. Hi im looking for a button, the harder you press it, the less
    resistance will run through the circuit, in effect a potentiometer but
    with a button instead if a turning knob.

    Im a newbee to the components world and was wondering if some knows
    how to find such a component and if there are any tutorial online on
    how to get started finding the right component etc. If someone know
    the cross reference code or whatever its called ill be very happy.

  2. Myron Samila

    Myron Samila Guest

    Well, this is an easy one.

    Yamaha makes electronic keyboards, and on some models, the keys are velocity and pressure

    I don't know exactly how they do this, I doubt it is a simple analog circuit, especially
    for an 88 key electric piano.

    But at least I can tell you that something like that does exist.

    Where do you live? There are many switch manufacturers that would be willing to send out
    a sample to you, that you can later buy from a dealer.
  3. A fast and cheap method is to use a piece of that black anti-static foam
    and a pair of metal contacts. The greater the pressure, the lower the
    resistance. You can experiment with this for starters.


    Chip Shults
  4. I live in Mountain View, CA.

    Would a dealer send out a sample to a hobbyist like me?
  5. Alan Holt

    Alan Holt Guest

  6. Look at force sensors, like this: That component was cool!

    This is what im trying to do.
    Im trying to detect if something is over the thing im trying to make.
    it has to be a device that gets pushed down. e.g. an optical solution
    wouldnt work.

    I guess a piezo electric solution would work since it can be made very thin
    (I need something that is 1-1.5cm thick).
    I think smart houses uses this in floors that can detect how much the person
    standing on it weighs and where he is going and where he as been. But i dont
    need that advanced feature, basically on or off with a couple of steps in
    between that could be adjusted electronically/programmatically for a
    threshold , e.g detect when (some signal voltage/resistance) more than x.
    The range of weight is approx between 2-20 kg

  7. JeffM

    JeffM Guest

    Yamaha makes electronic keyboards,
    Baldwin used [use?] wire key contacts
    and conductive elastomers as collectors (~bus bars).
    You didn't get the explosive attack lik you do with Hammonds,
    as the gradual-make contact softens it up.

    Chip Shults' suggestion has the advantage of being free.
    Use the conductive foam that they ship your ICs in
    and sandwich it between stiff metal plates.
  8. Bill Sloman

    Bill Sloman Guest

    As far as I know, velocity sensitive piano keys incorporate two
    switches, and the key velocity is sensed by measuring the time delay
    between the first key-closure and the second. This can be done quite
    easily and cheaply in the digital domain.

    The U.K. hobbyist magazine published a "build your own electric piano"
    project more than twenty years ago that - IIRR - worked on this basis.
  9. CWatters

    CWatters Guest

  10. I see pressure sensors in the conrad catalog ( ),
    page 781 a, whole range, itt says (translated from Dutch):
    10g - 10kG gives 2 Mohm to ca 3 kOhm
    There is a whole range, some type numbers:
    FSR-149NS 8 mm diameter (these are foil type sensors), 4,85 Euro
    oder nr 18 23 89 44
    (catalog page 781 with the other sensors).
    That one is 8mm diameter, , the bigest one is 46x46 mm hehe
    They specify 10 000 000 activations.
    Have not tried one but for that price it is easy to find out.
    You will need a (knob) construction on top of the foil, it has soldering
    wires it seems.

    Or, for a quick and sloppy answer, use a piece of IC protective foam.
    Or better foams available at outrageous cost from Emerson & Cuming.
    Avoid the silver ones; they stop working as soon as they get a
    fingerprint on them.

    We quickly sold out of these by advertising them on eBay as tinfoil hat

    We offer component finding services per


    Many thanks,

    Don Lancaster
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    voice: (928)428-4073 email: fax 847-574-1462

    Please visit my GURU's LAIR web site at
  12. The best way to do this at a resonable cost is to get a varible
    resistor, and mechanicaly couple it to a spring loaded lever. This
    would require some custom work to have the pot rotate as the lever is
    pushed in.

    Another approach is to get a slider pot, and mechanicaly couple it to
    a lever that is spring loaded.

    There are some varible resistance type push buttons on the market, but
    their prices are very expensive. If this is for a professional type
    job, then I would suggest going with something that is commercialy
    made. I cannot recall the manufactures at the moment.

    Jerry Greenberg
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