DIY Ultrasonic range finder for $5

After finding some ultrasonic transducers online for a dollar each [Kerry Wong] decided to create an ultrasonic range finder. The result is much like parallax’s PING))) sensor but much cheaper. His post is not only a good way to save some money, but also does a good job of explaining how ultrasonic sensors work.  The transmit circuit is essentially an H-bridge, much like what you would use to control a motor. To listen to the returning echo he uses a pair of high gain/low noise op-amps to filter and amplify the signal.  The board he uses to test the range finder (not included in the cost) is an ATMega328 running the Arduino boot loader.  He also provides lots of example code to boot.


  1. tristan says:

    source link seems dead, did we do that?

  2. bluewraith says:

    Domain seems to be down right now…

  3. zerth says:
  4. sneakypoo says:

    Sweet, hopefully it’ll help me once the page recovers from the DDoS :P I tried creating something similar a while back but gave up. Circuits like these seem more like voodoo than science *sigh*

  5. Slanesch says:

    @ sneakypoo

  6. Bill Porter says:

    Sigh… self hosting, through a DSL line no less. When will people learn? You can get a super cheap shared host for next to nothing now.

  7. golddigger says:

    Anyone know how to make a laser range finder. Small and light weight?

  8. zing says:


    camera and a laser pointer on a stick. If you know the length of the stick and the angle of the laser pointer compared to the camera, it is just trig.

    Smaller it is, the less accurate or more expensive it gets.

  9. golddigger says:

    Thanks for your reply! I have been through the google searches and I have seen the people doing work with webcams. But I was hoping for something less conpicious. The trig method with a cell phone camera and an eye safe laser pointer would be ideal, but I wouldn’t know where to begin. If anyone could point me in the right direction, it would be appreciated.

  10. adam says:

    I like seeing an embedded arduino like this. I’ve built arduinos before and they work great. $6 can easily replace a $40 basicstamp or $30 arduino board.

    very nice build

    I’m building a Geocache GPS that I’ll be able to load coordinates into and track them down. Its like a reverse reverse geocache lol. It will have a standalone arduino like this.

  11. Navic says:

    I love the Parallax Ping but hate its price so thank you for the great project!

  12. bluewraith says:

    Site is back up as of right now for anyone interested.

    I hate trying to incorporate a whole arduino board into a project. Its a waste of money and connectors. The only 2 cases I can think of would be a very temporary project (arduino controlled xmas lights) or a dedicated shield to bootload other AVRs.

  13. Mason Moore says:

    So where did he find the sensors? I can’t find them. If they’re a dollar each, then I definitely want some.

  14. jimmys says:

    golddigger, zing-

    A lot of cheap laser pointers can project designs like a smiley face or a star instead of just a dot. Measure the distance between star points or the eyes on the face.

  15. Rusty says:

    @Mason: I believe the site he got them from is;


  16. Mason Moore says:

    Thank you very much

  17. Lucassiglo21 says:

    my version:

    the range is 2cm-2mt and the accuracy is 3mm.
    now i have 6 and i am building another 5.
    i’m not using an H bridge, just a transistor and an inductor in parallel with the transducer (that gives you like 50v in the transducer)
    then i amplify the rx in 2 stages a couple thousand times with 2 high pass filters

  18. Lash says:

    How similar is this technique to the ultrasound used in baby scans? Could this be used as a Diy scanner or would there be risks? 3mm precision sounds very promising and a fascinating project, good work.

  19. strider_mt2k says:

    This an an appropriate app would be awesome to put onto a Spy Gear Video Trakr, if they would release the GPIO pins already.

    Sorry to veer off topic.

  20. Kaz says:

    Those look very nice. Have you considered selling them?

  21. Lucassiglo21 says:

    yeah, i have considered that, and i think i’m going to. i would sell a version with smaller transducers, 10mm in diameter. and i would love to use an smd microcontroller, but i couldn’t find them here.
    i’ve made these because the parallax ones are too hard to get, and they cost like 65 dollars each.

  22. Colin says:

    I recently had to purchase 5 high frequency ultrasonic capsules for a project. I found a site that sells them for $0.75 each (40 kHz), but with a minimum order quantity of 10.

  23. Justin says:

    I was hoping the source was going to be made available, I’d like to try building one or 3.

  24. Lucassiglo21 says:

    i am using a pic12f675, it sends the 40khz burst, and waits for the response from the RX amplifier, the ADC was too slow, so i am using an internal comparator and an internal voltage reference module to get the response.
    i didn’t publish the code mainly because it is used for a sumo robot competition, and i want to use them there. and i would be the first one with homemade ultrasonic sensors there. if i release the code and the schematics i lose my advantage in the competition.
    i am also selling them.

    anyway, it’s not that hard to do it. and you have to calibrate the detection voltages versus time for the comparator, and that varies with the construction and sensor sensitivity, so even if i publish the code, it will be probably useless.

  25. Lucassiglo21 says:

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