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Author Topic: A Sensitive DIY Ultrasonic Range Sensor  (Read 12000 times)
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CT, USA
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I wanted utilize several ultrasonic range sensors in my project, but they appeared to be quite pricey so I decided to build it myself.

And here's a detailed write-up on this project:
http://www.kerrywong.com/2011/01/22/a-sensitive-diy-ultrasonic-range-sensor/

This sensor is capable of measuring ranges well beyond 20 feet.

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Rural Arizona
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Very slick. Did you think about using an L293 for the transmitter?  I once picked up some non-"D" L293s by mistake,  but found them useful as drivers for LCD shutters.

They cost more than the discrete transistors,  but would save time when you're building multiples.
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That's pretty nice - although I don't consider the PING or most of any of the other ultrasonic sensors expensive; honestly, they are really cheap compared to what was available in the past. You basically had the equivalent of the the SensComp kits:

http://www.senscomp.com/

AKA - Polaroid rangers - which weren't cheap (and as you can see, still available - and still not cheap). Maxbotix also has fairly good sensors, though they aren't as cheap as others, either.

Something I am curious about (and I see this often in homebrew ultrasonic sensors) - why didn't you attempt to use a single sensor for both sending and receiving? Alright - I know it is more difficult to do, and hard to get your head wrapped around; I've always thought to try it myself, based on some designs from Hexamite:

http://www.hexamite.com/

...but using sensors similar to what you are currently using. I'm just curious more than anything; everybody seems to go for the simpler route of the PING style (not too mention, since the raw sensors used are so inexpensive, why not)...

Anyhow - great article, great device, great job!

 smiley
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nice work,
I have two pairs of transducers laying around, so I probably need to do the same thing some day.
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@ crosh: You have to admit though, two sensors look cooler  8-) And when mounted on top of a robot of some kind, tend to give the impression of eyes. I'm sure this plays a role too  smiley-razz
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@cr0sh,

Thanks for those links!  I have to admit that building something from scratch does feel good regardless of the material cost.  smiley-wink

Getting back to the one sensor question, The main challenge is to design a transmitter that is powerful and then at the same time to design a receiver that is sensitive.

In a one sensor design, the transmitter side usually is not bridged since the transducer needs to be multiplexed between sending and receiving. If the sender needs to be bridged the circuit will become even more complex.

Also a good analog switch chip that can deliver the power needed and has a low noise level is probably going to be expensive. But I think I might experiment with a single transducer design sometime just to see it myself.

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CT, USA
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Ran Talbott,

Yeah, I could have used some half-bridge/full-bridge chips to drive the transducer, but I don't have any lying around. On the other hand, I have hundreds of transistors right in my drawer smiley...
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Left Coast, CA (USA)
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Very nice, an experimenter's wet dream.  smiley-wink

As a side note for possible improvement, I recall playing with an exterminators Ultrasonic kit that Polaroid sold in the early 80s. In their receiving circuit they added a AGC (automatic gain control) function to the op-amp stages. Seems the return echo amplitude decreases with distance, so their amp stages would start up with a lower gain and increase gain over time to better detect the received signal and have better signal to noise ratio overall. I'm sure this would increase distance capability but at some added circuitry complexity.

Lefty
« Last Edit: January 23, 2011, 12:39:21 pm by retrolefty » Logged

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Ah yes. I'll was thinking of trying out AGC, maybe it'll go into my version 2. Thanks for the suggestion retrolefty!
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