ultrasonic distance measurement with a phased array

Thread Starter

FelixB

Joined Dec 26, 2022
33
hello everyone,
I saw a video these days and that brought up a idea. It was about phased arrays and making a "beam".
Here is the video link:
So my plan is that I use 16 transmitters (I ordered these in the 12mm variant) and 1 receiver and I want
to order them like this:
phased_array_sketch.png
To control them I would use a 11.1V power source (3x lithium-ion), a RP Pico 3.3V microcontroller,
transistors to drive them and to amplify the receiving signal.
My problem is:
  • that I don't know if the 11.1V is a good choice(because the only thing I can get out of the datasheet is, that Vmax is 120V)
  • I don't know the current draw of the transmitters(same problem, I don't see it in the datasheet)
  • I don't know which Transistor is suited for controlling the Transmitters and which for amplifying the receiver signal (I got BC327-25, BC-337-25, C1815, 2N3904, 2N3906, 2N2222, 2N2907, S8050, S8550, A1015)
Thanks in advance!
 

MrChips

Joined Oct 2, 2009
30,485
Piezoelectric ultrasonic transducers can be modeled as a capacitor. DC current is zero. AC current will depend on many parameters such as capacitance and signal frequency. The total current drawn by a large number of transducers will have to be determined experimentally.

You will need to drive each transmitting transducer with a sine or square wave. What you need is a low-side switch which can be implemented using an NPN BJT. 2N3904 and 2N2222 are common NPN transistors.

You will need to amplify the signal from the receiver transducer. A good design choice would be an op-amp band-pass filter tuned to the 40kHz ultrasound frequency. LM358 is a popular dual op-amp in an 8-pin DIP package.
 

Thread Starter

FelixB

Joined Dec 26, 2022
33
Thanks for the answer. I just ordered some LM358. When they and the transducer arrive I will make some empirical measurements so maybe we have some data for the future.
 

MrChips

Joined Oct 2, 2009
30,485
I would suggest that you gain experience first by building a simple ultrasonic range finder using just two transducers.
 
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