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What are they?

Discussion in 'Electronic Basics' started by Roger Dewhurst, Oct 8, 2006.

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  1. I have two 10mm diameter cylindrical cans about 10mm long. They are
    screened at one end and two pins at the other. They are labelled R3C 130
    and SCS-401 88.23. 401 is a bit fuzzy and may be something else. I think
    that they are sonic devices of some sort. Can anyone tell me how they are
    incorporated in a circuit?

  2. Tom Biasi

    Tom Biasi Guest

    They could be transducers or maybe flux capacitors.
    No one will be able to tell you how they are used until it is known what
    they are.
    Do you know anyone with a DeLorean?
  3. Bob

    Bob Guest

    I've got a Mr. Fusion. There are no such parts in it.


  4. Sounds like you have the version that was neutered.

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  5. Fred Abse

    Fred Abse Guest

    That would be eunuclear fusion ?

  6. Yep, surplussed from the Vienna Boy's nuclear power plant. They
    didn't work worth a damn. ;-)

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  7. Chris

    Chris Guest

    Hi, Roger. Seriously, they sound like they're a little too big to be a
    microphone. If the cylindrical cans are black thermoplastic, your
    parts may be piezoelectric beepers. There are three basic kinds of

    1) Those that have all the drive circuitry enclosed, and just require
    that vThey sound like they're too small to have enclosed drive
    circuitry, so you'll have to drive them yourself.

    2) Those that have an internal transistor and a couple of resistors --
    you have to add a transistor and one or two parts to make them work,

    3) the bare piezoelectric element.

    The best way to tell if you've got a 1) is to just apply a low DC
    voltage, and see if it beeps (option 1) or just clicks (probably option
    3). Judging from size, I'd guess you've got #3. The piezo concept
    means that a change in applied voltage causes the piezo element to
    flex, and that flexing the element produces a change in voltage. You
    can use piezo discs as sensors (flex causes voltage), and you can also
    use them as beepers (voltage causes flexing like a tiny speaker) by
    applying an AC voltage to them of the recommended mechanically resonant
    frequency (usually 3KHz or so for the smaller units).

    For most applications, a digital drive signal is applied to both sides
    of the device to produce the "AC". For the really small ones (like
    yours), you might be able to do something like this if you've got a
    74HC14 and a 5V power supply (view in fixed font or M$ Notepad):

    | ___
    | .--|___|--. Piezo
    | | R | Beeper
    | | |
    | | | |.-.|
    | | |\ | |\ A || || B
    | o---| >O--o--| >O-----|| ||-------.
    | | |/ | |/ || || |
    | | | |'-'| |
    | --- | |
    | C --- | |
    | | | |
    | | | |\ |\ |
    | === '-----| >O--| >O-----------'
    | GND |/ |/
    (created by AACircuit v1.28.6 beta 04/19/05

    The 74HC14 is an inverer IC with schmitt trigger inputs. You can use
    that with an R and a C to produce an audio frequency square wave as
    shown, with R and C chosen for the appropriate frequency (again,
    usually around 3KHz for the smaller piezo elements). This is fed to
    the other gates, so that when A is high, B will be low, and vice-versa.

    This means that, for a 5V supply, you're applying a 10V peak-to-peak
    square wave to the piezo transducer. If you've chosen a frequency
    close to mechanical resonance, and the capacitance of the piezo element
    is small enough to be effectively driven by the HC14, you'll get an
    audio tone.

    This drive method is only recommended for the smallest piezo speakers.
    Larger ones can be driven by an LM556 or even a capacitive bridge
    driver for the larger piezo elements. This bridge-type switched DC is
    much more efficient than sine wave AC, because the fast rate of change
    of the square wave produces a much faster flex of the piezo element
    (and hence, more sound).

    I hope this has been helpful. As to your specific part, I believe
    there are about 4 or 5 manufacturers of these little piezo buzzers in
    Taiwan, and everyone puts their own numbers on and sells them under
    their own trade name. Can't help you there.

    If you're interested in designing one into a project, you just might
    want to buy one or two. The smaller ones are very inexpensive even in
    small quantities.

    Good luck
  8. Jamie

    Jamie Guest

    does that generate the required Jigga Watts?
  9. These are in small aluminium cans. I bought them years ago in a Dick Smith
    sale but without any documentation. I think that they are ultrasonic
    devices of some sort.


  10. Can you post a picture to

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  11. BobG

    BobG Guest

    Put one on a signal generator with a 1k R in series and sweep it up to
    40khz.... the volts across the R will peak at the resonance freq. Or
    maybe dip. Anyway, look for a maximum or minimum around there.... real
    helpful, huh?
  12. jasen

    jasen Guest

    by your description they sound like ultrasonic transducers, but could be
    electret microphones etc...

  13. Eeyore

    Eeyore Guest

    An electret mic will have a kind of 'black felt' on the opposite end from the

  14. I think that is what they are. Which is which and how do I use them in a

  15. Chris

    Chris Guest

    Hi, Roger. Can't help you on the "which is which" side (possibly try
    DSE?) but here's an older EDN article on a minimum parts count uC-based
    ultrasonic rangefinder using parts similar to yours:

    Look at the second article (p. 2).

    Good luck
  16. Archilochus

    Archilochus Guest

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