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A simple ultrasonic range detector?????

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by steven_first_2001, Jan 23, 2004.

  1. steven_first_2001

    steven_first_2001 New Member

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    Hey pepole!!! My teacher asked me to make him a ultrasonic range detector for backing up his turck. I wanted to know if there is any way (that anyone kinows of) for hoking up a Devantech SRF04 range sensor (or any others that range form ~1' to ~10') up to a lcd display WITHOUT using a stamp chip or any other expensive parts. Or if anyone knows of any kits that are compleat (sensors disply and whatever else you need). I would be verry happy if anyone could help me out on this!!! thanks!
    You can e-mail me directly if you like at steven_first@hotmail.com
     
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You need a processor of some kind, STAMP's are expensive because it is a complete system, rather than just a PIC. A 16F628 (which is cheap) would interface them together easily, and require hardly anything extra - apart from writing the assembler software for it.
     
  3. lopesn1464

    lopesn1464 New Member

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    Don't forget, you'll need a programmer to flash the chip. I've seen them on sale for as low as 30 bucks. Good luck!
     
  4. dave

    Dave New Member

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  5. pokiri

    pokiri New Member

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    Try PSoC

    There is an application note AN2048 available at http://www.cypress.com. It uses less components. Good luck

    Pokiri
     
  6. Roff

    Roff Well-Known Member

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    The range you mentioned is 1 inch to 10 inches. Do you mean 1 ft to 10 ft? If so, I can show you how to do it without a microcontroller. The display would be a 10-LED bargraph. I'll design it for you if this is what you want. You'll have to build and test it yourself.
     
  7. steven_first_2001

    steven_first_2001 New Member

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    Realy????????????

    Hmmm.... A ten LED setup sounds realy good and easy to build! Please do show me how to build the thing!! I am only a junior in a vocatinal school so I know a lot but it's a bit early for microprocessors. I will gladly except the offer. Post it, send it to me, or what ever you want
     
  8. Sebi

    Sebi New Member

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    I agree with Ron: never seen ultrasonic circuit who can work under 25cm distance.For parking sonar need sometimes 2..3cm (in the city....).
     
  9. Optikon

    Optikon New Member

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    It's true. I have used this model before (with a micro though).
    It works as advertised: 3 INCHES to 10 FEET

    I'm pretty sure the transducers are those old polaroid camera types that were used for auto-focusing (hence 10' ability).

    My experience was:
    Getting _accurate_ range at 10 feet was tough..
    Sensing small objects at 3 inches was tough..

    BUT for your application, you don't need the accuracy I had some trouble with.
     
  10. Roff

    Roff Well-Known Member

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    Here is the schematic for the analog, non-microcontroller, ultrasonic distance monitor. It has 1 ft resolution, with a range of 1-10 feet.
    U1 is connected as an astable multivibrator, providing a 20Hz trigger pulse to the SRF04. The width of the echo pulse from the SRF04 equals the round trip time for the ultrasonic pulse. Since the nominal speed of sound is 1100 ft/sec, the echo time for an object 1 ft away will be T=1*2/1100, or T=1.82 milliseconds.
    Q1 and U6a form a current source which charges C9 with I~45ua, generating a ramp on C9 which rises at a rate of dv/dt=I/C9, or dv/dt=0.17v/millisec, which corresponds to dv/ds=0.17*1.82=303mv/ft.
    At the end of the echo, the current to C9 is diverted to ground by analog switch U5a, which causes the voltage ramp on C9 to stop and be held. This voltage is buffered by voltage follower U6b. The trailing (falling) edge of echo is differentiated and inverted by C10-R8-U3d. This generates a positive pulse at the input to analog switch U5c, sampling and holding the stopped ramp voltage on C11. Thus a DC voltage proportional to distance is presented, via voltage follower U6c, to the input of U7, an LM3914, which is an LED bar graph driver. When the sample pulse ends, a logic "1" gets clocked into "D" flip-flop U4a. This turns on analog switch U5b, discharging capacitor C9. The flip-flop is reset by the arrival of the next echo pulse, releasing C9 to begin charging again.

    Calibration:
    The LM3914 can be used in bar or dot mode depending on the position of S1. If you use bar mode, be aware that the LEDs can draw as much as about 200ma from the 5 volt regulator (hence the heat sink and the 1 watt 10 ohm resistor). Dot mode is much lower power, but is probably more difficult to interpret.
    For distance calibration, simply aim the transducer at a target which is 9.5ft away and adjust RV2 to where the 9th LED is turning off and the 10th LED is turning on. The reference voltage should ideally be 3.0v, but this can vary considerably due to component tolerances, altitude, atmospheric pressure, and air temperature.
    The LED current, and hence brightness, can be adjusted with RV1 to a maximum of about 20ma for each LED.

    I considered using a switching regulator, but decided they are less accessible to the average hobbyist. There are a number of other options available for the 5 volt regulator.
    The TLV2404 is a quad op amp with picoamp input current, rail-to-rail input and output capability, and capable of running on a 5 volt supply. You can probably get it as a sample from TI, or you can buy it from Digikey.

    I simulated parts of this, but I haven't built it, so there may be errors. If anyone builds it, let us know about your success or failure.

    It would obviously be much simpler, hardware-wise, to do this with a microcontroller, but our OP, Steve, specifically requested a non-digital solution.

    Edit 1/30/04:
    I just noticed that in the schematic, I gave U3 the wrong part number. It has been corrected.
    Edit 1/30/04:
    In and Out were swapped on LM7805.
     

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  11. pasanlaksiri

    pasanlaksiri Member

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  12. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    All range finders I have seen look for the first echo. Has anyone seen a range finder that looks for all the echoes. In this thread we have already talked about PIC + LCD display. I am thinking of a LCD display that will show multiple objects. Is there a reason why the second, third and forth echoes cannot be seen? (I know new thread.) I am still thinking of a back up display but with more information.
     
  13. thinkinggee

    thinkinggee New Member

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    fellaas please i need some help i am working o my final year project .design and implementation of an ultrasonic motion dector.i need help real quick,need materiasl for all the paper work ,and how to implement it thanks
     
  14. scarboro

    scarboro New Member

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    Freebie SONAR

    There's a freebie "Super Simple SONAR" here, which uses just six common components: Urban Ministry Live And Unplugged: Super Simple SONAR. This has a few metres'/yards' range, and can be used, among other things, as a parking SONAR, or for security applications.
     
  15. brandoncosta

    brandoncosta New Member

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    Last edited: Mar 30, 2011
  16. shokjok

    shokjok Member

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    An alphanumeric display would be beyond your ability, lest it would make you very popular among parents and commercial drivers. For that, you need a team of engineers and designers, like the major automakers.
     

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