Cheap pressure sensor

Discussion in 'The Projects Forum' started by Jefecito20, May 4, 2010.

  1. Jefecito20

    Thread Starter New Member

    Apr 26, 2010
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    0
    Working on a pressure measuring system (up to 50 psi). So far, the pressure sensors I've looked at are all too expensive for a small class project (in excess of $100 or almost Rs. 5000, which is the total budget we've been given). Does any one know of cheaper alternatives.

    Something similar to this, hopefully:

    ST1510

    http://pdf1.alldatasheet.com/datasheet-pdf/view/145477/ETC/ST1510.html
     
  2. BMorse

    Senior Member

    Sep 26, 2009
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    I am not sure if you can get something like this unit http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=480-2521-ND, but this is less than $30.00 US....

    Or you can create your own using a piezo "speaker" like the ones found in musical greeting cards, the piezo it will output a voltage proportional to the pressure applied to it...... search google for piezo sensors/transducers circuits


    Wikipedia says:
    here is a circuit I use to buffer the output of the piezo for use in 5 volt TTL circuits, D1-D2 prevent the output voltage from going over 5 volts....

    [​IMG]



    B. Morse
     
    Last edited: May 4, 2010
  3. bertus

    Administrator

    Apr 5, 2008
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  4. Externet

    AAC Fanatic!

    Nov 29, 2005
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    You can always find someone ready to rip you off on a pressure sensor.

    An oil pressure sender from any car that has a gauge on the dashboard will be in the range you want; and can be $0 at the wreckyard. Cheaper and simpler I do not know.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Just tried a piece of conductive foam for pressure vs resistance, the kind CMOS chips are stored in. Some was conductive, some was not. Used 1 " X 1" between two metal plates. No pressure = 200k ohms, gradually increased pressure up to 50+- lb =300 ohms. Cheap enough?
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
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    Ummm.. no. My time is worth too much to make that affordable.

    Can you ship it to me? ;)

    Were the results repeatable? I was wondering if the foam had lost any sensitivity regarding the sensor viability after the first test.

    Did the foam seem to return to the initial 200k ohm point after pressure was released?
     
  7. BMorse

    Senior Member

    Sep 26, 2009
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    I actually use those kind of homemade pressure sensors for my robotics projects....

    [​IMG]

    B. Morse
     
  8. retched

    AAC Fanatic!

    Dec 5, 2009
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    So it works well?
     
  9. BMorse

    Senior Member

    Sep 26, 2009
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    for the most part it does, but it does tend to loose resistance in time.....

    The piezo disc sensors on the other hand, have worked for pressure sensors, touch sensor, shock, vibration, etc.... and they are very versatile and can be used in a variety of applications....

    I recently just used a hand full of them to make a set of electronic drum triggers for my MIDI drum set
    [​IMG]

    You can check out the work log here >> http://www.morse-code.com/id208.htm


    B. Morse
     
  10. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
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    Have a look for a digital tyre pressure gauge.

    You may well find one at a reasonable price & the sensor should be fine for 0 - 50psi.
     
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