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SRF04 Ultrasonic Range Finder — Parallax Forums

SRF04 Ultrasonic Range Finder

Eric REric R Posts: 225
edited 2005-02-16 00:33 in BASIC Stamp
On my new car I installed a front air dam that sits close to the ground.·It really looks nice but since it won't clear a curb without being torn off I would like to install a SRF04 range finder in the air dam for obvious reasons. Anyone know of a way to semi waterproof this unit? There must be a material that won't affect the operation since a lot of these new vans have them on the rear. Anyone have suggestions?

Thanks in advance

Comments

  • steve_bsteve_b Posts: 1,563
    edited 2005-02-15 02:59
    There was another thread, where the poster wanted to measure tank level in a boat and the sloshing became an issue with the SRF getting wet.

    not sure what they eventually went to.

    The SRF's are basically small speakers.· So, if you take a speaker and put it in a waterproof box....does it work?!· Not well, as it needs to move air to create the sound.· So 'boxing' in the SRF won't do.· And any 'waterproof' speakers you come across are no different than other speakers except that their materials are all coated and covered, but it's exposed enough that it's action still moves air.

    I know there are cars that use ultrasonic...but they must have a weatherproof casing that still allows them to work.· They're probably more costly than the SRF's and may decay after a winter of salt and water.

    Have you thought about IR?

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    Steve
    http://members.rogers.com/steve.brady
    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • ForrestForrest Posts: 1,341
    edited 2005-02-15 03:10
    There are weatherproof ultrasonic detectors available. Cadillac and some other car companies have been installing them on bumpers for a few years now and they seem to hold up pretty well. I've built parking meters that had ultrasonic detectors built-in. These were designed to hold up to all outside weather conditions for a number of years. Use Google to search for sources.
  • Eric REric R Posts: 225
    edited 2005-02-15 03:17
    Thanks,

    I was looking to use the SRF04 since it could be mounted with two small holes and go almost unnoticed. The factory units are not exactly what I was looking for.
  • Eric REric R Posts: 225
    edited 2005-02-15 03:22
    steve_b said...

    There was another thread, where the poster wanted to measure tank level in a boat and the sloshing became an issue with the SRF getting wet.

    not sure what they eventually went to.

    The SRF's are basically small speakers.· So, if you take a speaker and put it in a waterproof box....does it work?!· Not well, as it needs to move air to create the sound.· So 'boxing' in the SRF won't do.· And any 'waterproof' speakers you come across are no different than other speakers except that their materials are all coated and covered, but it's exposed enough that it's action still moves air.

    I know there are cars that use ultrasonic...but they must have a weatherproof casing that still allows them to work.· They're probably more costly than the SRF's and may decay after a winter of salt and water.

    Have you thought about IR?

    The car will only see a possible rainy day and a hose during a wash. IR might be a possibility, however, I thought that IR would need to reflect off something (unlike a cement curb or parking block).
  • steve_bsteve_b Posts: 1,563
    edited 2005-02-15 04:01
    ultrasonic has to bounce off things too!· But definately the IR needs a more 'optically' reflective surface!

    I don't know where you live, but if you're in a snow belt, ANY moisture that settles in there will corrode wires and the tin can casing of the ultrasonics.

    I have to seriously pressure wash the truck every couple weeks to get all the salt debris off.· You'd be surprised where the stuff gets.

    Anyhow...off topic.· DEFINATELY be sure to weatherproof your cct....run wires out to the sensor and maybe you can get away with replacing the sensor heads after a couple winters.·

    don't get me wrong...the SRF is a perfect choice for your application....but the weather will get it.· (think the wicked witch and Toto..."and you're little dog too"...ok not that dramatic maybe).

    Certainly what Forrest says about the ones car manufacturers use....that's something you'd want as far as it's sealing.· But they'd get $$ I'd imagine!

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    ·

    Steve
    http://members.rogers.com/steve.brady
    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • aridaiosaridaios Posts: 57
    edited 2005-02-15 04:58
    Devantech has released a new I2C ultrasonic range finder named SRF235.
    http://www.robot-electronics.co.uk/shop/Ultrasonic_Rangers1999.htm
    I have bought one for experimentation.·It·has a sensor that it's surface seems to be rather water resistant. Maybe you could modify one·and place the sensor apart from rest of circuit which you could protect easily.

    Michael
  • Jim McCorisonJim McCorison Posts: 359
    edited 2005-02-15 23:13
    It was I that was looking for waterproof ultrasonic sensors. I had an email exchange with the folks at Devantech and none of their sensors are waterproof. They did state that they have received many requests for such a feature, but have yet to develop one.

    SensComp makes a series of piezo electric transducers which are waterproof www.senscomp.com/kseries.htm. They have an evaluation kit www.senscomp.com/specs/piezo%20kit.pdf which has a sample of all their different piezo units.

    From my research, the SenseComp units look like to best bet, but I've not ordered them yet as I'm trying to limit myself to one project at a time.

    Jim
  • steve_bsteve_b Posts: 1,563
    edited 2005-02-15 23:49
    What do depth finders use?!· I know some are mounted in the boat and others are dropped over the side....

    It's not ultrasonic....but just curious!

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    ·

    Steve
    http://members.rogers.com/steve.brady
    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • Jim McCorisonJim McCorison Posts: 359
    edited 2005-02-16 00:33
    From what I've seen, most of the common ones are at either 50kHz or 200kHz. 50kHz gives greater depth range and bottom contours, where as 200kHz provides better target definition. 200kHz is what the most common recreational grade depth sounders and fish finders use. It is limited to around 400 feet of water depth, depending on the quality of the unit. I think, but don't know for a fact, that most are 200kHz because a) it is cheaper to do than 50kHz, and b) the vast majority of boats don't need to know water depths beyond a few hundred feet.

    Jim
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