## Ultra sound

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I found a pair of ultrasound transcivers in my junk box. It is marked with Mitshubitchi logo + EFR-OCB40K2. Ã˜ = 24 mm, L = 9 mm.

Google did not show me any datasheet, and I wonder:
1.
What frequensy might it be? I gues 20 KHz

2.
I will feed it with a dipulse, 1/2 posetive , and then a 1/2 negative sycle. (H-bridge) The voltage should be near the max voltage. What voltage may I try?

HM

HM

I'll put money on 40KHz.

Imagecraft compiler user

There are several ways to determine the resonant frequency.

One method is the data sheet, (if you eventually locate one).

One method is to drive it with a fixed amplitude voltage signal while measuring the current flow through the transducer as you sweep the frequency.

A signal generator or an AVR programmed as a DDS signal generator makes this easy.

Another method is to feed the sweep frequency to one transducer while watching the amplitude of the signal received by the other transducer. The received signal will peak at about the resonant frequency.

I'm not sure what the drive voltage should be. A lot of robotics ultrasound transducers are run at 5 V or 12 V. I don't know what the driver is for a typical automotive vehicle bumper transducer these days.

Years ago I did an under water ultrasound project, (think sonar), and I think the driver was 90 V, but that was many years ago. Point being, there is an incredible range of transducers and it is hard to guess its power rating.

JC

Well, the part number does include "40K". I am with Bob.

Ross McKenzie ValuSoft Melbourne Australia

mossige wrote:

1.
What frequency might it be? I guess 20 KHz

It's quite simple by pulsing low frequency via higher impedance voltage generator: it should ring nicely at Fres on edges. Scope is needed, of cause.
Quote:

2.
I will feed it with a dipulse, 1/2 posetive , and then a 1/2 negative cycle. (H-bridge) The voltage should be near the max voltage. What voltage may I try?

Quite a high voltage is needed for excitation; somehow similar in dimensions fishing sonar transducer is fed ca.120V pulse, IIRC. In sonar application TD shall be fed "spiked" voltage, so a bridge/bipolar pulsing is not necessary. Implemented usually by HV capacitor discharge via fast switch.
Continuous AC excitation is widely used in power applications - cleaning etc: the configuration there is a H either half-bridge autogenerator.