Ultrasonic transducers

Discussion in 'General Electronics Chat' started by adrenalina, May 19, 2015.

  1. adrenalina

    Thread Starter Active Member

    Jan 4, 2011
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    Hello everyone. I have been looking for an ultrasonic transducer, but haven't been able to find many, mostly transmitter and receivers, not transceivers. I was able to find this one on Newark: http://www.farnell.com/datasheets/1759986.pdf
    The only problem is that it is in stock in the UK. I have searched on mouser and digikey, but haven't found any transceivers.

    Does anyone know others places to find ultrasonic transducers?
     
  2. DickCappels

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    Aug 21, 2008
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    Well, if you only need one or a pair, you can always rip some out of an ultrasonic burglar alarm.

    If you can find one high enough in frequency, a high fidelity tweeter might work for you.
     
  3. RichardO

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    May 4, 2013
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    Interesting question.
    I worked with diagnostic ultrasound transducers and they were always "transceivers". These transducers typically operated at in the range of 2 to 5 MHz frequency.
    40 KHz transducers do seem to be either transmitters or receivers. I am not sure why. I suspect that if you use a transmitter version as a transceiver it will work but at reduced efficiency/sensitivity. It might be worth a try. You may find it works good enough in your application.
     
  4. blocco a spirale

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  5. JohnInTX

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    The transducer you select depends entirely on what you want to do with it. It ain't trivial. Frequency, sensitivity, beam width etc all have to be taken into consideration.

    What are you doing with it?
     
  6. adrenalina

    Thread Starter Active Member

    Jan 4, 2011
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    Thanks for the links. I intended to measure the distance to objects using ultrasound, because of my application I can't use the hundreds of ultrasonic modules that exist. After doing some reading online, I found out that the limitation of using 1 transceiver is that the minimum range is limited to about 30cm. I need a range of about 5cm to 2m aproximately, so I think I'm going to use a pair of transmitter and receiver, which doesn't have that limitation of minimum range.
     
  7. JohnInTX

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    That depends on the transducer and what is driving it. We use a narrow beam 220KHz transceiver that ranges from about 7cm to 50cm. On the short end of the range is how long the transducer takes to ring-down after transmitting to get it quiet and switched to receive. The long range is determined by the acoustic power transmitted, how much is reflected (narrow beam is better here) and the receiver sensitivity - among other things.

    A dual transducer setup can be easier to use if you have the space.
     
  8. AnalogKid

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    Most crystal-based components can behave as both emitters and receivers, especially if you have control over the transmitter power.

    Maplin (UK) sells pairs for $10: http://www.maplin.co.uk/p/40-khz-ultrasonic-transducer-hy12n

    Digi-Key has individual transmit and receive devices for $5 each, or an assembled module good to 2 cm for $30.

    ak
     
  9. ian field

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    Oct 27, 2012
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    With the low price of distance meters in various discount stores, it seems hardly worth going to the trouble of building one.

    IR distance sensors have better resolution and are not affected by ambient noises. AFAIK: Sharp do an off the shelf IR distance module.
     
  10. AnalogKid

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    Sharp had a great one for this distance range, but we got an end-of-life notice and had to design it out.

    ak
     
  11. ian field

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    There must be a second source somewhere.

    Some Epson product lines were similar to some of Sharp's lines - but I think Epson were generally more focussed on memory products.
     
  12. AnalogKid

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    We couldn't find one. There are lots of reflective sensors, but most of them are intended for go/no-go detection. Sensors with any kind of linear and calibrated output are rare.

    ak
     
  13. adrenalina

    Thread Starter Active Member

    Jan 4, 2011
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    What I am basically want to make is a sensor like this one: http://www.ebay.com/itm/1pcs-Ultras...420?pt=LH_DefaultDomain_0&hash=item3a9150794c

    But I want to make my own so that it sends the information using I2C instead of pulses.

    I have used the sharp sensors and the only problem that I have found with them is that they are affected by fluorescent light. If pointed directly to this light it gives incorrect measurements.
     
  14. AnalogKid

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    But it's only 99 cents! Whatever you build from scratch will cost 20 times that. I don't know of any differential-timing-edge to I2C interface chip, so it will need its own microcontroller if you want it to speak I2C. So, since you are committing to a uC anyway, add one to the 99 cent wonder to convert the timing pulses to whatever I2C message format you want to create.

    It is interesting that there is an RS-232 interface chip on the board. It might be there only to act as a charge pump, or this thing might have serial comm built in.

    ak
     
  15. blocco a spirale

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  16. adrenalina

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    Jan 4, 2011
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    I understand how cheap those sensors are, but because of space constraints those sensors might be a bit too big, I'm going to verify if I could somehow fit it and add a board with a micro to handle the I2C communication.
    Thanks blocco for the link. I find it weird how the price can jump so much from the regular sensors to an I2C sensor.
     
  17. ian field

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