# Creating a Circuit with Ultrasonic transducers

Hey all,

I recently ordered a set of long range ultrasonic transducers from here: Ultrasonic Sensors
I was wondering if anyone can offer any advice on how I can hook these up to start reading distances.

Send out an ultrasonic pulse and measure how long it takes for the pulse to bounce back.

Can you be more specific? I am very new to programming and working with the arduino. It is my understanding that I need to feed 40khz into one, then amplify the other and listen for a reply(they came in a pack of 2). I am not quite sure how to make this happen though.
Thanks.

For another \$6 you can buy a pair of sensors mounted on a circuit board complete with its own microcontroller.
For a beginner it makes interfacing with so much easier as you can use the existing ping library.

Agree with mjbmikeb - unless you have access to, and know how to use an oscilloscope, these things are tricky to build and debug, with echoes typically only producing signals in the millivolt range.

If you're looking for circuits, google "devantech srf04" - the circuits used to be freely available, but be aware that they use a PIC, not an AVR to drive them.

Ok, i'll look into that. The reason I chose those sensors is because of the range approx. 18m where as the Devantech SRF04 only has a range of approx. 3m. I figured I would just get those sensors and build around them.

18 metres is an awfully long way for ultrasound.
You'll need to put some real power into the transmitter.
In a cluttered environment (and most will be out to that sort of range and beam angle) expect lots of multipath returns.

Well the basic idea for the thing i am trying to build is to keep track of the distance a moving object is from the point of origin. From approx 18m to lets say around 3m

How big is the "moving object"?

BigTop:
Well the basic idea for the thing i am trying to build is to keep track of the distance a moving object is from the point of origin. From approx 18m to lets say around 3m

The easy way is to buy a \$150 laser range finder as used by golfers. (These have a minimum range of 5m.)

The more interesting way....
Vehicle has a wireless "camera remote shutter control", Arduino, microphone and 40kHz band pass filter.
The origin has the corresponding wireless receiver, another Arduino to generate a 40kHz square wave bust, a cheap 100W public address amplifier turned up full, and a 50W piezo tweeter.
Fit ear plugs, (the tweeter will probably make loud clicking sounds.)
Trigger a pulse from the vehicle and measure the time for the sound to be received.
Calibrate for 3 and 18m.
Reduce the transmit power until it just works at 18m and remove ear plugs.

AWOL:
How big is the "moving object"?

Lets say the size of a car.

any ideas about what I need to get these particular ultrasonic sensors to work? I already bought them so I might as well use them. I read somewhere that I could use an LM833 as an amplifier and a MAX232 to provide a larger voltage to the sensors in a circuit similar to this one: SRF04 Technical Documentation however is there anything else that I would need on top of that to make this work?

Go here - check out raron's posts:

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1224198029

I just noticed that the images in the old forum for that post don't come up properly (they're too tiny to read) - here is raron's user profile on here:

He seems like he is still active - so maybe he might post up something; if not, I'm pretty sure I snagged a copy of that thread and the large images, maybe I can repost them somewhere...

cr0sh:
I just noticed that the images in the old forum for that post don't come up properly (they're too tiny to read) - here is raron's user profile on here:

Arduino Forum

He seems like he is still active - so maybe he might post up something; if not, I'm pretty sure I snagged a copy of that thread and the large images, maybe I can repost them somewhere...

awesome. that looks like it will help a lot. Thanks

I came across this schematic and I was thinking I could model it ---> A Cheap Ultrasonic Range Finder

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!

You mean T1, an NPN transistor?

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.