Harvesting ultrasonic sensors

With many modern cars coming equipped with an array of ultrasonic sensors mounted in the bumpers, it stands to reason that many junk yards have them too. [jimk3038] points out that, unless they’re crushed, they’re probably good. The list of features on these is pretty long, including being short proof, water proof,  EMF proof and fast. These tough little suckers can be used in a multitude of projects and can have a range of roughly 2 meters.  [jimk3038] documents in great detail how to use these things as well as offering some sample code to get you started. Why didn’t we think of this?


  1. AlanKilian says:

    Mystery part could be an HE40106 Schmidt trigger hex inverter.


    Pincount, package and power and ground match.
    (Of course so do tons of other 14-pin logic parts!)

  2. Sariel says:

    once again an idea I had that far outstretched my budget or electronic comprehension. I’ve been wanting to use some of these as a proximity alarm system on my car. would be an awesome alternative for many of the current expensive systems on the market today. I would imagine having a carpc connected with the cell towers could also alert you via sms to proximity. with an added camera and a bit of code you could even get a picture of the crime and call the police. ahhh the imagination of a student hard at work on things other than homework. lol

  3. This is a great idea! Cheap ultrasonic sensors!

    How well would these automotive sensors work underwater? I’ve been wanting to build a Vexilar style device. I failed last summer. :(

  4. Renee says:

    Have people had much experience with junk yards? Whenever I do searches for them all I seem to get are polished front-end manager offices.

    Is it really that easy to just go to a junk yard and walk around and take what you want? Paying for it of course.

  5. Rounderkatt says:


    try looking for local “pick your part” type places.

  6. Steve Hoefer says:

    @Renee Yup. Bring your own tools, wander around and take what you like. Pay on your way out. (At least thats how they work where I am.)

    Ultrasonic sensors aren’t the only cheap takeouts from cars. I have a road following windshield mounted camera that’s just begging for a project. A high quality camera mounted to an ARM micro, heavily ruggedized. For basically nothing.

  7. Daniel says:

    Care to share what model you pulled it from, where in the car it was, and what it was originally used for?

  8. PhilKll says:

    This is great, I used to work in a body shop, and would pick what I could. Broken tail light got me 60+ high wattage LEDs, part of a prius, loads of large capacity capacitors, more relays and fuses than I know what to do with, motors, and random boards to recycle components. I have 1 of these, used to be 2, but I didn’t know what I was doing and let the smoke out of one. Thanks for the article, been waiting for something like this.

  9. MS3FGX says:

    It seems like different states have different rules about junk yards. I know I could never find a decent junkyard that was open to the public in New Jersey, but if you cross the bridge into PA there are like 3 of them within a 5 mile radius.

    Prices are usually ridiculously low, but of course it’s a real gamble as to what you will find in there. The junk yards I have been to certainly never had anything new enough for ultrasonic parking detectors, all the cars were early 1990’s and older.

  10. CutThroughStuffGuy says:

    How do these work? 12v to them and they close a contact when an object gets to about 6 ft away? Some can detect relative distance but probably need an arduino or the like to interpret the analog signal?

  11. Taylor Alexander says:

    As people have touched on, there are two kinds of junk yards:
    The kind where you go out with tools, disassemble the car yourself, take the parts you want, and pay some small amount for what you’ve got,
    and – The kind where they pull the parts, and charge you much closer to the retail value of the part.

    Obviously you’d want to go to the former. I know Pick-n-Pull is one such place. They’re all over California, but there are some dotted around the rest of the country.

  12. strider_mt2k says:

    I used to peg Womp Rats in my T-16 back home and they’re not much bigger than two meters.


  13. CutThroughStuffGuy says:

    The quote should be:

    “I used to bull’s-eye womp rats in my T-16 back- home. They’re not much bigger than two meters.”

  14. Whatnot says:

    Junk yards have mean dogs though :)

  15. moo says:

    Pick-n-Pull FTW!

  16. Tom says:

    Anyone have any experience with scrap yards in the UK?

  17. holly_smoke says:

    EMF proof? You mean they are unaffected by voltage?

    Or did you mean EMI proof? As in Electro Magtnetic Interferance…

  18. nutwiss says:

    Tom 90% of UK Scrap yards are the pick-n-pull type. Just wander in, the scruffier the better – don’t take a bag, just a screwdriver or two, a pair of pliers and a socket set and say you just want a mooch. They should be quite accomodating. I can’t speak for the rest of the country but Brum has dozens of decent scrappers.

  19. toojeep4u says:

    @strider_mt2k: That was too funny.

  20. tantris says:

    i found that for many non-car projects the junkyard prices aren’t that great.
    the reason is that car parts are overpriced and junkyards sell at a certain percentage compared to new.
    that makes general non-automotive parts (relatively) pricey: a broken cordless drill might be a better source for a 12v motor than one pulled from a vent control, because at the junkyard it is still a replacement part not just a motor.

    same goes for water pumps, switches, and probably ulrasound transceivers. unless you got a nice junky junk yard that doesn’t act as a used car parts business, thrift stores or surplus stores will be cheaper.

  21. mithras says:


  22. poot says:

    Be carefull when you do pull an ntact sensor from a bumper. The plastics used on those (especially Toyotas) are ver brital. I have had many break when trying to salvage them.

  23. Paul says:

    I wonder if the data from the UPA module is relayed onto the CAN/OBD2 bus… could make for some neat car mods. (Tailgater sensor anyone)

  24. WolfinPDX says:

    And with this, I’m Batman!

  25. Steve Hoefer says:

    @Daniel It was apparently a 2008 Cadillac, don’t remember the model. It was stuck to the windshield(inside) above and behind the rear view mirror. It watches the lines on the road and alerts the driver when it thinks they’re straying out of the lane.

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