What is Ultrasonic Transducer : Working and Its Applications

Frequency is defined as the number of signals or waves that can be appeared in a fixed time. Units for the frequency are Hertz (Hz). These frequencies are divided into several ranges depending upon the frequency values. They are Very Low Frequencies (VLF), Low Frequencies (LF), Medium Frequencies (MF), High Frequencies (HF), Very High Frequencies (VHF), Ultra-High Frequencies (UHF), Super High Frequencies (SHF), and Extremely High Frequencies (EHF). The frequency range may be varies based on the type of frequencies. The frequency range of VLF ranges from 3 to 30 kHz. The frequency range of LF ranges from 30 kHz to 300 kHz. The frequency range of MF ranges from 300 to 3000 kHz. The frequency range of HF ranges from 3 MHz to 30 MHz. The frequency range of UHF ranges from 300 MHz to 3000 MHz. The frequency range of SHF ranges from 3 GHz to 30 GHz. The frequency range of EHF ranges from 30 GHz to 300 GHz. This article discusses an overview of the ultrasonic transducer and its working.

What is an Ultrasonic Transducer?

The ultrasonic transducer is one type of sound-related sensor. These transducers send the electrical signals to the object and once the signal strikes the object then it reverts to the transducer. In this process, this transducer measures the distance of the object not by the intensity of the sound. These transducers use ultrasonic waves for the measurement of a few parameters. It has a wide range of applications in various fields. The frequency range of ultrasonic waves is above 20 kHz. These are mainly used in measuring distance applications. The following image indicates the ultrasonic transducer.


These transducers can be defined as a transducer which is used to convert one type of energy to ultrasonic vibration. By these ultrasonic vibrations, this transducer measures the distance of the object. These are available in two types like active and passive

Ultrasonic Transducer Working Principle

When an electrical signal is applied to this transducer, it vibrates around the specific frequency range and generates a sound wave. These sound waves travel and whenever any obstacle comes, these sound waves will reflect the transducer inform of echo. And at the end of the transducer, this echo converts into an electrical signal. Here, the transducer calculates the time interval between the sending of the sound wave to the receiving the echo signal. The ultrasonic sensor sends the ultrasonic pulse at 40 kHz which travels through the air. These transducers are better than the infrared sensors because these ultrasonic transducer/sensors are not affected by the smoke, black materials, etc. Ultrasonic sensors exhibit excellence in suppressing background interference.


Ultrasonic transducers are mainly used for finding the distance by using ultrasonic waves. The distance can be measured by the following formula.

D = ½ * T * C


Here, D indicates the distance

T indicates the time difference between sending and reception of ultrasonic waves

C is indicating the sonic speed.

Circuit Diagram

The ultrasonic transducer has a transmitter and receiver circuit, they built with 555 timers or CMOS technology. The transmitter and receiver of this transducer are works on the same frequency.

The transmitter of this transducer transmits the ultrasonic waves towards the object and when the sound waves strike the object then the sound signals are converted to ultrasonic and electrical signals. The following diagram indicates the transmitter circuit diagram of the ultrasonic transducer.


The receiver circuit receives the signals after the striking of ultrasonic waves to the object and then convert them to electrical form. The following diagram indicates the receiver circuit diagram of the ultrasonic transducer.


Ultrasonic Transducer Types

There are various types of ultrasonic transducers available based on factors like piezoelectric crystal arrangement, footprint, and frequency. They are

Linear Ultrasonic Transducers – In this type of transducers, piezoelectric crystal arrangement is linear.

Standard Ultrasonic Transducers – This type is also called as convex transducers. In this type, the piezoelectric crystal is in a curvy form. For in-depth examinations these are preferable.

Phased Array Ultrasonic Transducers – Phased array transducers have a small footprint and low frequency. (its center frequency is 2 MHz – 7 MHz)

For non-destructive testing, the ultrasonic transducers are again having different types. They contact transducers, angle beam transducers, Delay line transducers, immersion transducers, and dual element transducers.


The applications of Ultrasonic Transducers are

These transducers have many applications in different fields like industrial, medical, etc. These are having more applications because of ultrasonic waves. This helps finds the targets, measure the distance of the objects to the target, to find the position of the object, to calculate the level also the ultrasonic transducers are helpful.

In the medical field, the ultrasonic transducer is having the applications in diagnostic testing, surgical devices while treating cancer, internal organ testing, heart checkups, eyes and uterus checkups ultrasonic transducers are useful.

In the industrial field, ultrasonic transducers have few important applications. By these transducers, they can measure the distance of certain objects to avoid a collision, in production line management, liquid level control, wire break detection, people detection for counting, vehicle detection and many more.

Advantages and Disadvantages

Any system has advantages and a few disadvantages. Here will discuss the advantages of the ultrasonic transducer.

  • These ultrasonic transducers can able to measure in any type of material. They can sense all types of materials.
  • The ultrasonic transducers are not affected by temperature, water, dust or any.
  • In any type of environment, the ultrasonic transducers will work in a good manner.
  • It can measure in high sensing distances also.

The disadvantages of these transducers include the following.

  • Ultrasonic transducers are sensitive to temperature variation. This temperature variation may change the ultrasonic reaction.
  • It will face problems while reading the reflections from small objects, thin and soft objects.

Thus, this is all about an overview of an ultrasonic transducer. From the above information, finally, we can conclude that this device is used to measure the distance to an object by using sound waves. It measures distance by sending out a sound wave at a specific frequency and listening for that sound wave to bounce back. Here is a question for you, what is the frequency range of this transducer?