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Author Topic: Creating a Circuit with Ultrasonic transducers  (Read 3688 times)
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I came across this schematic and I was thinking I could model it ---> http://www.micro-examples.com/public/microex-navig/doc/090-ultrasonic-ranger.html

however I am unclear on what one part of the circuit is.

The part of the schematic in question is the area to the right of R1 and below D1 (the red with the arrow pointing down and to the right)

Thanks for all the help!
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I don't think you connected the grounds, Dave.
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You mean T1, an NPN transistor?
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If you don't know what a transistor is then you are not ready to do such a project. This circuit will defiantly not give you the range you are looking for. You need to drive the transmitter harder, you need to amplify the input from the receiver and you need to disable the receiver during the time of the ping to stop it being saturated.
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Read the following
http://www.robot-electronics.co.uk/htm/srf04tech.htm
If none of it makes sense and you don't have a storage oscilloscope, or know how to use one, then you are going to end up building something that doesn't work.
For an absolute beginner, a project of this kind rates as a magnitude 8 on the Richter scale of difficulty.

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He seems like he is still active
Kinda smiley-razz I haven't checked in for a little while now.

Btw yes the schematics image is on the verge of being too small (that is if you enlarge it somewhat by clicking it - otherwise yes, absolutely too small to read).

As for ultrasonic distance sensors allow me to point to a better and more awesomer circuit than my simpleton, by AlphaZeta: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1295749011
Btw I still haven't pursued this more since my old post a year ago.
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Ok so I got the transmitter working( I can hear it clicking) however I can't seem to receive a signal. I built this rangefinder based on raron's which can be observed here -->

http://s557.photobucket.com/albums/ss11/rar0n/Electronics/Arduino/?action=view&current=Ultrasonicsensor1.png
as well as the breadboard here -->
http://s557.photobucket.com/albums/ss11/rar0n/Electronics/Arduino/ultrasonic/?action=view&current=IMGP6404.jpg

Anyone have any idea why I am not able to receive a signal? I'm pretty damn sure I built it the exact same way.
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Any chance of posting a photo that is actually larger than a postage stamp so we can see it?
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Since MediaFire (and photobucket) insist on resizing my image, I gzip'ed it instead. Winrar and similar for windows should hopefully be able to extract it.
New link: http://www.mediafire.com/file/2weve835zy74x5s/Ultrasonic%20sensor%201.png.gz

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Ok so I got the transmitter working( I can hear it clicking)
You have an exceedingly good hearing? smiley-razz

Anyway, to get this pretty simple and unstable(?) circuit working, you should have a (oscillo)scope and watch it with, while you adjust RV1. Lacking that, perhaps skipping one stage will help, maybe even two, with a reduced range of course. But it might get you started. As well as experimenting with RV1, as its just as a simple threshold adjustment. Pretty much just something I cobbled up without too much thought.


Also, as previously stated, AlphaZeta's solution is really much better!
http://www.kerrywong.com/2011/01/22/a-sensitive-diy-ultrasonic-range-sensor/

Except something I just noticed; about his note about using higher voltage to drive the transmitter. Do not do that with that bridge circuit (essentially the same as mine), as the arduino output has 5V (if its a 5V arduino, of course). You'd have to change it somewhat then, an additional inverting stage would be needed to shield the arduino output from higher voltages.
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I don't think you connected the grounds, Dave.
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You have an exceedingly good hearing?
It is quite easy to hear the clicks from 40kHz transducers driven hard.
Not the fundamental, obviously.
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You have an exceedingly good hearing?
It is quite easy to hear the clicks from 40kHz transducers driven hard.
Not the fundamental, obviously.

Well if you can't hear the fundamental frequency (40khz) and harmonics are multiples of the fundamental, what is it you can hear from such a transducer? Maybe just a mechanical 'noise' of the transducer flexing in it's mounting case when excited?

Lefty
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It is the step output you can hear. That is if you are sending out bursts of 40KHz at say one second intervals you will hear it click at one second intervals. The pulse train will have frequency components at the lowest rate of modulation. So it's not the 40KHz you can hear.
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BigTop,  Maybe take an existing $8.50 ultrasonic distance measurement unit, remove the transmit sensor and add power driver circuit and your transmit transducer and get that to work. Then replace receive sensor with yours and try to get that to work?? 

I have some basic Ultrasonic How-To here: http://arduino-info.wikispaces.com/UltraSonicDistance

You really need access to an oscilloscope to see these invisible signals.. it's a challenging project even WITH a scope...

Regards, Terry King
...In The Woods In Vermont
terry@yourduino.com
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Fiddled around with it a little more I was getting a read of 269in and 0in and the serial monitor was changing between those two numbers. I have since fiddled with it some more and I am not getting a straight read of 270in waving my hand over the transducers does not change the distance. Any ideas?
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