Comments on: DIY Ultrasonic Rangefinder

By: Mohammed

Mohammed — Wed, 01 Jun 2011 18:11:26 +0000

hi
I’m using the same concept for my range project
but when i tried to simulate it using Multisim v11.0
it won’t simulate “giving me an error without knowing where the error is”
the photo for my circuit is below
http://a.domaindlx.com/lio2000/Images/transmitter.JPG
I hope it works
if the pic didn’t open keep refreshing

is everything right their
it is my graduation project and I’m on deadline here

By: Keith Neufeld

Keith Neufeld — Thu, 11 Mar 2010 02:17:48 +0000

Lolo, I don’t think I’m likely to be able to see what’s wrong with your rangefinder from the circuit alone — I expect I’d probably have to play with it for a while with a scope watching things at different places in the circuit. Even if you felt like sending it to me, I’m afraid I really don’t have time to take that on right now.

You said you had it working with two transducers — why not use it that way?

By: Lolo

Lolo — Wed, 10 Mar 2010 14:48:12 +0000

exactly, i see this ring, but i don’t see the echo. it’s possible to send u my circuit(schema) per mail, if u see it, perhaps u can see something.. or not. But il really don’t know what i can do to solve this problem :s

By: Keith Neufeld

Keith Neufeld — Wed, 10 Mar 2010 12:21:52 +0000

Lolo, I’m sorry but I really don’t know quite what’s going wrong with your transducer. One thing that comes to mind is that a transducer will “ring” (vibrate) for a while after sending a pulse, and the commercial single-transducer rangefinders have a “dead” period after sending the pulse before they listen for the echo, but it sounds like you may be doing that already.

By: Lolo

Lolo — Wed, 10 Mar 2010 08:52:41 +0000

Hello Keith,

me i try to build an ultrasonic range finder but with an tranducer. This transducer must send and receive the pulses. But I’m not able to receive the pulses.. if i use 2 tranducers (one as emitter and an other one as receiver) there is no pbl! Have u an circuit or schema or something else to find my error and to understand better on how i have to this circuit?

My transdcuer works with 12v, and my microcontroller gives only 3.3v so.. i use one NPN to invert the PWM and to obtain a PWM with 12v.. and afeter i use a PNP to invert again the signal. With this solution i don’t polarize the transducer all the time.. In simulation it’s work.. when i use each stage separatly it’s works perfectly too.. but combined not!

Thank u for u answer

It’s for an personnal project

By: Keith Neufeld

Keith Neufeld — Mon, 08 Mar 2010 12:32:37 +0000

Shad’mehr, is this for a class assignment?

By: shad'mehr

shad'mehr — Mon, 08 Mar 2010 07:06:35 +0000

hi
I’m electronic student
can u help me ?~!!!!!!!!
i want to make a rangefinder which have sense a Accuracy 1mm
(& it will ranges distance of a liquids)
please help me
tank u

By: ryan

ryan — Sun, 30 Aug 2009 03:33:12 +0000

i imagine the transmitter rings for a long time because the transistor remains open, while the piezo (practicaly a capacitor) froms a tank circuit with the inductor… in the single transducer scenario both pins of the piezo are grounded, that should kill the oscilation immediatly… as for mechanical vibration in the PCB, mounting brackets etc… that’s probably the same for both single and dual transducer rangers… and just have to wait for the noise to die down… dual transduceers make sense when you want long range, one with dedicated tank circuit the other with an amp… but for short distances i see no advantage in using two… and costs more

By: Keith Neufeld

Keith Neufeld — Sun, 30 Aug 2009 03:03:25 +0000

Ryan, some of the newer ones have a single transducer. But the reason to have two is that the transmitting transducer tends to ring (you’re driving it at its resonant frequency) for quite a while after you stop the drive signal — long enough to make it impossible to detect an echo coming back from a near object.

By: ryan

ryan — Sat, 29 Aug 2009 00:59:50 +0000

Hi
i too want to build a cheap range finder, i have a piezo with a cone built into it, it’s from one of those ultrasonic pest control devices (i didn’t notice it having any effect on bugs, i could just barely hear it so it ended up anoying me instead)…
why do all units have two transducers??? my idea is to hook it up to a PIC with a resistor in parallel like pavel says. one wire to PWM and the other to ADC.
1) make ADC pin into output ground.
2) 40khz on PWM for… 50ms?
3)make PWM pin into output ground, turn ADC pin into ADC input
4)wait for noise to go away, then wait for echo.

why would this not work?? i only need like 20cm range, so pwm out should be enough, also, i know the amplitude i can expect for the echo and it’s length, that way filter out other noise… i’m surprised not to find projects like this alreaddy on the internet, can anyone tell me why?