Best Simple Detector Circuit for Ultrasound

Thread Starter

Jonesville

Joined May 27, 2023
5
I want to create and detect ultrasound at about 300kHz using piezo elements. I have a circuit that produces a square wave using a tlc555 IC, and I was wondering if a LM567 IC would be good for a detector circuit. If so what would be the best way to do it, or what other IC would I use? I'm hoping to make a detector that works well but is as simple as possible. Thanks.
 

Papabravo

Joined Feb 24, 2006
21,225
The answer to your question is to read the datasheet. If you were to do that you would find the following information:

1706148078084.png
This would tell you that the part is not guaranteed to be able to receive 300 kHz. OTOH it just might work if you are lucky. Wouldn't you rather have a better solution? From what I remember it is hardly a simple part to use.
 
Last edited:

UweX

Joined Sep 2, 2020
33
The most critical part of this circuit is the transducer. Depending on your purpose you may select on with high directional characteristics, which gives you the best sensitivity. So first get a suitable transducer and study that data sheet. Usually a transmitting transducer may need a driving voltage of 100 V peak-peak to cover a wide range. Also the LM567 may need a low-noise amplifier in front of it to get the signal to a suitable level. Noise can be reduced by putting an LC-filter at the input, consisting of the transducer capacitance and an external inductor.
Also some effort is needed if you want to use a single transducer. In that case your receiver input need protection during the transmission and ringing phase of the transducer.
And, as Papabravo pointed out, you are okay if you need to build a single or maybe up to 10 circuits for this system, but for a high volume product you should never ever operate a circuit outside specified operating range.
 

Johnfoxwell

Joined May 23, 2021
15
You don’t say what the application is.
You need to write a Requirement Specification as a first stage. This should include the output power, attenuation, reflecting coefficient etc
Without this you have no chance of success.
 

Thread Starter

Jonesville

Joined May 27, 2023
5
The end goal is for an Arduino board to detect when the transducer is hit by ultrasound. I've bought piezo disks at 300kHz. I am not an electrical engineer. So, I have a lot to learn. I was hoping to stick with battery power. So, no 100V. If not the 567, then what would be a simple but good alternative?
 

Thread Starter

Jonesville

Joined May 27, 2023
5
By the way, the data sheet for the 567 shows that its center frequency can go up to 500kHz. So, 300 should be fine. But would it be the best for an ultrasound circuit?
 

Papabravo

Joined Feb 24, 2006
21,225
By the way, the data sheet for the 567 shows that its center frequency can go up to 500kHz. So, 300 should be fine. But would it be the best for an ultrasound circuit?
If you read the datasheet carefully the typical or mean value is 500 kHz, but the minimum guaranteed value is 100 kHz. To me that means "not for sure, not for certain, but probably" it will work at 300kHz. Your mileage may differ.
 

Johnfoxwell

Joined May 23, 2021
15
It seems that you have no knowledge of the power transmitted, attenuation of the medium etc. Until you know that you don’t know the voltage at your receiver.
 

UweX

Joined Sep 2, 2020
33
For Arduino there is an ultrasonic module around, HC-SR04. On the Arduino website you find some introduction for it.
As a beginner you should start reading the documentation there.
Then explain, why you can't use that module for your application. is it just NIH (not invented here ) ?
 

Sensacell

Joined Jun 19, 2012
3,448
The end goal is for an Arduino board to detect when the transducer is hit by ultrasound. I've bought piezo disks at 300kHz. I am not an electrical engineer. So, I have a lot to learn. I was hoping to stick with battery power. So, no 100V. If not the 567, then what would be a simple but good alternative?

The concept of "detect when the transducer is hit by ultrasound" is too vague, it's not useful as a specification.

Using the analogy of light, imagine detecting a candle a kilometer away, or direct sunlight at noon? The huge range that this signal might encompass begs clarification.
The solution will be radically different depending on the signal levels.

Explain what you are trying to accomplish, from the basics.
 

Johnfoxwell

Joined May 23, 2021
15
Exactly. Typically for sonar, the input signal could be a few micro volt.
The project does not have a clear approach.
Failure to plan is a plan to fail.
 

Thread Starter

Jonesville

Joined May 27, 2023
5
What I mean is a circuit that allows the Arduino to know when the receiver has been hit by ultrasound so it can act on it. I want to have one transducer to be able to move separately from the other. I don't want to use echoes. I want the transmitter to be at one point and the receiver at the other point.
 

Lightium

Joined Jun 6, 2012
169
What I mean is a circuit that allows the Arduino to know when the receiver has been hit by ultrasound so it can act on it. I want to have one transducer to be able to move separately from the other. I don't want to use echoes. I want the transmitter to be at one point and the receiver at the other point.
This is a programming problem. It would be better to approach this by seeking programmer. All you need to do is read a mic programmatically, say with 16 bits, and then when you get a measure above some 16 bit threshold (above the noise level) you program Arduino to activate the 555.
 

Sensacell

Joined Jun 19, 2012
3,448
This is a programming problem. It would be better to approach this by seeking programmer. All you need to do is read a mic programmatically, say with 16 bits, and then when you get a measure above some 16 bit threshold (above the noise level) you program Arduino to activate the 555.
Nobody ever gets far ignoring the analog reality by going straight to code.
You need a viable signal to digitize first.
 

UweX

Joined Sep 2, 2020
33
Okay, now we know more about it. So why don't you use one module HC-SR04 for transmitting and one for receiving ? What distance you want to cover ? Maybe for something greater than 6 m you need some beamforming structure on the module to improve directivity and therefore distance.
Is my understanding right, you are trying to construct something like an ultrasonic "light barrier" ? Please note, the module or the transducers on the module I mentioned are only for inside operation. The transducers resp. the piezos are moisture sensitive, so outside operation is not possible. There are other encapsulated transducers available like the ones used for ultrasonic parking assists in cars, but here are the piezo crystals protected against environment.
 

Thread Starter

Jonesville

Joined May 27, 2023
5
Sorry, I should have given more info earlier. I want to measure the distance between two objects without aiming the transmitter in a certain direction. A speaker emits the sound and the receiver detects it and sends a signal to the Arduino, maybe by going through a comparator IC comparing the input to 0V, which then can calculate distance. The distance would be about three feet at most. I want to use higher than 40kHz to get close to millimeter accuracy. That's why I bought 300kHz piezo disks. I'm using the 555 to drive the transmitter.
 

UweX

Joined Sep 2, 2020
33
Thanks for that information. So for three feet you can live with a 555 as driver, at 12 V supply it should generate enough amplitude. You didn't answer my question about in house or outdoor application, but with this short distance I assume an inside application. That limits the temperature range and makes special effort for frequency tracking over temperature unnecessary.
Still on the receiver side you need to pay attention to the filtering, even a PLL is filtering. You need filtering structures to suppress out-of-band noise and improve the SNR and therefore distance. But any filtering will deform an ideal rectangular transmitting packet to something with limited attack and decay times. So just using 300 kHz transducers doesn't give you millimeter resolution without considering the filter characteristics.
There is a difference between a piezo disk and a transmitter. It is some sophisticated mechanical work to mount the piezo and contact it. So my advice is to first build the transducer ( depending on your application it may require some protection of the sound emitting surface) and then characterize it. A commercial transducer usually has the radiation pattern documented in the data sheet. So you have just the piezo, can you do this pattern characterization ?
So there are still many variables. A signal path calculation still makes much sense. (electrical power to transducer, emitted sound pressure level, attenuation up to the receiver, acoustic level there, electrical level at the receiving transducer and the electrical signal processing.
 

Ya’akov

Joined Jan 27, 2019
9,165
Welcome to AAC.

Is this school work?
Why are you trying to measure distance? What practical problem does this solution propose to solve?
How did you get to this point in the design of the solution? What else did you consider? Are you sure you haven’t turned your ”solution” into a new problem to be solved?
 
I want to create and detect ultrasound at about 300kHz using piezo elements. I have a circuit that produces a square wave using a tlc555 IC, and I was wondering if a LM567 IC would be good for a detector circuit. If so what would be the best way to do it, or what other IC would I use? I'm hoping to make a detector that works well but is as simple as possible. Thanks.
How have you determined distance differentiation?
Acoustic range finding requires a pulse of a known energy level, exact timing, and time varied gain to keep the receiver in the envelope necessary for function.
Things to consider are wavelength, medium(air?), losses, and interference, and frequency stability/phase angle.
I don't see a non echo solution.
You might review time of flight resources to gain some prospective.
It seems you feel that you can over simplify a rather complex problem.
In example: you want to determine distance to a constant radiated noise. But you don't know which direction it is coming from so you use an omni directional sensor. This reduces sensitivity of your signal by orders of magnitude. Thus requires much higher amplification, on top of not knowing at what level is needed to detect an unknown value. Are you planning to use sound level attenuation as your measurement process? I don't see that being accurate enough for mm level measurement. You may only gain detection at best. Accuracy is unlikely.
 
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