What use for ultrasonic transducers?

Discussion in 'General Electronics Chat' started by GS3, Nov 3, 2007.

  1. GS3

    Thread Starter Senior Member

    Sep 21, 2007
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    Years ago I started a project with a couple of ultrasonic transducers. The idea was to build a volumetric motion detector and it worked, sort of, because it easily gave false alarms.

    It had a transmitter which transmitted a constant tone and a receiver not placed directly across but pointed at the room so that it received all the sum of all the echos. Any movement in the area disturbed the echos and the amplitude received oscillated which was easy to detect. The principle did work well but even some movement of vibration of the walls (like loud outside noises or a truck going by) made the thing go off. It might have worked in a cave or castle with solid walls. So I never used it for that purpose and the whole thing went into a shoe box where it has remained over the years.

    I always thought some day I'd come up with a new idea for which I can use the transducers but in all these years I have never come up with anything so the question is what could I do with a couple of ultrasonic transducers?

    I suppose I could design some alarm or sensor that worked by interrupting the direct beam between them. That would avoid the echo problem but I really cannot think of any use for such a sensor. (I mean me personally, not that it would not have them.)

    A range finder is more complex and I have no use for it anyway.

    Maybe some simple, on/off, remote control... that would be good if I needed such a thing.

    Any other ideas?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Confusing bats?
     
  3. hgmjr

    Moderator

    Jan 28, 2005
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  4. GS3

    Thread Starter Senior Member

    Sep 21, 2007
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    That is a good idea but I don't happen to have any bats which need confusing :p

    Thanks. I looked in there and found those projects fall into several categories which are pretty standard and I had already thought of but I really have no use for any of them.

    - Animal repellents, dog whistles, etc.
    - Range finding (measure echo delay)
    - Volumetric detection (unreliable as I said)
    - Object detection by direct beam interruption (seems best use)

    Anyway, I'll keep thinking. I hate it when I have a solution in search of a problem to solve. :p
     
  5. h.d

    Active Member

    Oct 22, 2007
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    the ultrasonic sensors is used in autonomous robots as object detector and range finder.
     
  6. hgmjr

    Moderator

    Jan 28, 2005
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    How about using an ultrasonic transceiver to measure the distance between the ground and an object suspended in a magnetic field. The distance measured would be used in a PID controller circuit that would adjust the magnetic field strength to maintain the object at uniform height above the ground.

    hgmjr
     
  7. h.d

    Active Member

    Oct 22, 2007
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    how can u explain more?
     
  8. GS3

    Thread Starter Senior Member

    Sep 21, 2007
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    Well, I am not planning on building anything like that but I know what you mean and this raises an interesting question. I have seen such things usually controlled with an optical sensor and I have to wonder if an accoustical system would work or if it might not be fast enough for the feedback requirements.

    I think I may end up building some simple 'break of the direct beam' detector as these seem quite reliable. These days it seems infrared would be used instead for such an application as it is more reliable.

    As I say. I seem to have a solution in search of a problem. I can't think of a situation where infra-red would not work better except for animal applications and I am not really interested in that. Besides, I am not sure what frequencies would be required for that, I believe a bit over 20 Khz, but these transducers are something over 40 Khz so I doubt they would be suitable for that.

    It might work for some short distance range finding. I'll have to think what type of application I could use some short distance range finding. Maybe sensing liquid level in a tank or something like that.
     
  9. subtech

    Senior Member

    Nov 21, 2006
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    How about using such a transciever to set on the ground mid span between two poles and measure the height above the earth of newly strung power line conductors?
    Linemen would love something like that. The sag of the new conductors could be could be verified in several places and this would be much easier than some methods that are used presently.
     
  10. GS3

    Thread Starter Senior Member

    Sep 21, 2007
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    subtech, I doubt it would work well for that purpose due to the distance, noise, having to keep a direction, etc. IR would be better suited and even that I believe would be challenging.

    Some years ago I knew a guy who was going to spend some money commissioning the development of a system to be mounted on top of trucks on the runways of a certain airport. It was supposed to warn the truck driver when he was getting too near an overhead wing of an airplane and it was intended to avoid these collissions which are not uncommon.

    I told him to save his money as it would not work because ultrasounds just do not have the range and are too vulnerable to noise anyway. He took no notice and went ahead with the development anyway but when I asked him after a few months he avoided the subject so I conclude I was right and he wasted his money.
     
  11. Dragon

    Active Member

    Sep 25, 2007
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    Ah! The same thing happened to my Ultrasonic Motion Detector and Range Finder that I built 2 and half years ago!

    But I realised it was a wonderful engineering application.

    -You can measure water depth by this project (application of range finder)

    - It can be used for level surveying (application of range finder)

    - For measuring unknown depths in a variety of situations (application of range finder)

    -The Transmitter and Reciever can be projected upwards with an 'angle', so that the beam is in a position to be reflected off an intercepting object. (Kind of a crude radar design)

    - In security systems. On interception of the beam b/w the transmitter and reciever an alram goes off.
     
  12. GS3

    Thread Starter Senior Member

    Sep 21, 2007
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    Yes, that seems like a good project but I have thought if the sensors might not be damaged by the humidity.
    Hmmm, this might be problematic and I think IR is better suited for this application.
    Direct beam interception seems like the best use and it can be for an alarm or for counting objects, etc. Still, it is difficult to imagine where an IR beam would not work better.
     
  13. Nomad

    Active Member

    Oct 21, 2007
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    ultrasonic cleaning device? kidney stone eliminator? non line of sight communications or remote control? they have their uses, they were around way before ir leds were invented. Our first remote controlled tv used them. a monster zenith console.
     
  14. subtech

    Senior Member

    Nov 21, 2006
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    GS3
    I beg to differ with you. I've seen laser aimed ultrasonic equipment used for this and many other power line related purposes before, and more than once.
    Actually, it's quite common. You might want to check here:

    http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/7368/19993/00924406.pdf http://www.arrl.org/qst/2006/04/han...ansformer+Using+Transfer+Function+Method.html
    http://tdworld.com/overhead_transmission/power_birds_power_lines/index1.html

    A few years ago, I was able to inspect/investigate an ultrasonic equipped line clearance "substation" that had been constructed directly under a major transmission line owned by a large power company in Mid USA. Its function was to continuously monitor the height of the line conductors above the earth. The info was used by the power dispatchers in making decisions as to whether additional loading of that particular line could be safely allowed. The transmission line voltage was 345KV and the minimum allowed clearance from the station location was on the order of about 28 feet. The station has been in continuous service now for 7 years.
    I've got more examples if you'd like.
     
  15. GS3

    Thread Starter Senior Member

    Sep 21, 2007
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    That's a thought. I have always liked the dishes where you can clean your eyeglasses. But I think these transducers are not very powerful and a regular speaker at much lower frequency could use more power and work better. And, again, I am not sure these transducers would stand up well to humidity.
    Well, I don't have any kidney stones in need of elimination but even if I did I am not sure I'd want to go the DIY route with it. :) And. again, my guess is the transducer would not be powerful enough. You probably need some serious power for that.
     
  16. thingmaker3

    Retired Moderator

    May 16, 2005
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    "Ruben's tube" is the propane wave demonstrator. Truly fascinating toys!!
     
  17. GS3

    Thread Starter Senior Member

    Sep 21, 2007
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  18. bundick

    Active Member

    Dec 19, 2007
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    My Ultrasound Burglar alarm kept going off about Noon.
    Turns out the sunlight coming through the south Bay window, lit up the Dust particles in the air till the alarm thought it was a body in motion.
    I had to turn the sensitivity down until it could just see me if I stepped out into the hallway.
    So your home made Burglar alarm just needs a little sensitivity training.
     
  19. beenthere

    Retired Moderator

    Apr 20, 2004
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    To bundik - you might look more closely at posting dates.
     
  20. bundick

    Active Member

    Dec 19, 2007
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    My apologies. I'll look next time.
    I ran across that thread while searching for Ultrasonic information.
    Dick.
     
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