circuit for ultrasonic transducer and receiver

[superchiku]

i wanna know if there are any schematics for making ur own sonar using the ultrasonic receiver and transmitter pair

[airman00]

search google, man!!!!

[superchiku]

not found

[airman00]

http://www.leang.com/robotics/info/articles/minison/minison.html

one of the first hits on google

I would recommend buying a sonar sensor instead of making it

[superchiku]

sonars are very costly to buy besides it is not available at the place where i live so i was deciding of making one

[airman00]

sonars are very costly to buy besides it is not available at the place where i live so i was deciding of making one

do you have an oscilloscope or a frequency counter to test the sonar

[superchiku]

nope not bought one

[Steel_monkey]

I see many people here want to make sonar. I think it would be great to unit our attempts and create DIY sonar that will not require o-scope or frequency counter ( it is not really needed), just robust enough to be solder-and-play. I already have all parts required, but don`t have time to prototype  . As I see it: ATmega 8 will be used as to drive and measure. It will be connected to **232 TTL-RS232 converter, driving  sender with high voltage in differential mode, i.e. it will give be 20 Vp-p. Receiver circuit is not very clear for me. I am planning to use two inverting amplifiers with non-inverting input biased to half of supply voltage. Then, there will be rectifier with two diodes and two capacitors, and then non-inverting amplifier and voltage follower will be connected. I don't want to use negative voltage from **232 for negative supply of op-amps because it is not very clear (voltage doubler). I have not decide yet, what to use. It is possible to use comparator waiting for pulse, and ADC with minor digital processing and auto gain control with digital potentiometer. It will be possible to detect far objects with big dimensions behind small objects. I was planning to create rectifier using op-amp, but is works poor with single supply.      However, receiver is not clear to me, because I have not prototyped it yet, I only used simulation.

[superchiku]

sonar is more trustworthy than ir can u plzz tell the schematic??

[airman00]

sonar is more trustworthy than ir can u plzz tell the schematic??

depends for what application

http://www.societyofrobots.com/member_tutorials/node/71

[superchiku]

sonar is better than sharp IR in many ways dont u think

[Ro-Bot-X]

Check out this circuit. It was made as a Lego compatible sensor, but it can easily be modified to work as a regular sensor. http://www.extremenxt.com/ultra.htm

[airman00]

sonar is better than sharp IR in many ways dont u think

thats why I wrote this

http://www.societyofrobots.com/member_tutorials/node/71

[superchiku]

ok ok cool

[ALZ]

Hi: I make a few many many years ago. They didn't work on the robot I had because the robot used belts and made too much noise for the sonar. Now a days they sell the whole thing on a chip but if you still want to make one yourself it would be very cheap. Here are some helpful hints: You only need ONE transducer, it can receiver and transmitter. DO NOT use OP. amps, too much noise on them.  Plain transistors work fine, you would need to build a three stage amp from them. The rest of the chips I used were things like 555 timer, counter chips, display chips and analog chips. If I was to build one today I would try using a PIC.

i wanna know if there are any schematics for making ur own sonar using the ultrasonic receiver and transmitter pair

[Steel_monkey]

Plain transistors  ... In the I-net I saw only one schematic with three-stage bipolar amplifier in receiver curcuit, all others used opamps. Perhaps, this is a trade-off between place economy and noise immunity, but I am not sure. Could you tell ,which opamps had you used? And had you used  AC coupling with suitable cut-off freequency? Had you rectified signal? What the gain was? I saw oscillograms where high niose was declared at the output of sonar, but it was not told to be connected with opamps, that is why I am asking. In theory, after rectificatrion and filtering ( just getting envelope of the sent pulse of 7-9 square waves), high-freequency noise should be suppresed. Perhaps, one amplification stage with high slew-rate and GBW and low noise will work. It is interesting for me because I am planning to build USRF and getting info around the net. 

[ALZ]

Hi Steel_monkey:

When I said it was a long time ago, I mean a long time ago, about 30 years. It was most  likely a 741, it had a unity gain bandwidth of 1 or 1.5 MHz. I was only getting a voltage gain of about 12. Yes I used AC coupling. Then I tried a video amp 733 120 MHz  bandwidth. I don't know if I was doing something wrong or what but all I ever got out of that was almost more noise than signal. Maybe the 40 KHz signal was too low for the video amp?  No mine design didn't use a rectified signal at all. All I did was send a few 40 KHz pulses to the  transducer. Stop the ringing of the transducer and then switched the input to the amp. When the signal came back, if it passed the trigger level I would stop the counter.  The range was about a 2/3 of an inch to about 18 feet. If you have birds in the house don't use sonar by them! When they chip it has a high frequency part that will pass right thru the 40 KHz transducer!

Plain transistors  ... In the I-net I saw only one schematic with three-stage bipolar amplifier in receiver curcuit, all others used opamps. Perhaps, this is a trade-off between place economy and noise immunity, but I am not sure. Could you tell ,which opamps had you used? And had you used  AC coupling with suitable cut-off freequency? Had you rectified signal? What the gain was? I saw oscillograms where high niose was declared at the output of sonar, but it was not told to be connected with opamps, that is why I am asking. In theory, after rectificatrion and filtering ( just getting envelope of the sent pulse of 7-9 square waves), high-freequency noise should be suppresed. Perhaps, one amplification stage with high slew-rate and GBW and low noise will work. It is interesting for me because I am planning to build USRF and getting info around the net. 

[Steel_monkey]

Thanks for info! I was planning to use cheap opamps to make shematic reaiser to copy (358) , but this chenges everything. Now I am planning to use somethinh like AD8606- pecision, wideband, low noise  high slew-rate operational amplifier. It is much better than 741 (noise is not even specified!) and should work fine.
30 years.... I was not even at project that time  .