How To Make Ultrasonic Sound Generator Using 555 Timer

I’ll demonstrate a basic ultrasonic sound generator in this lesson that may be used as a sound generator, a mosquito repellent, and other things of that such. This project makes use of an astable mode multivibrator with an IC 555 to change the variable resistance in order to obtain the appropriate frequency. Here, I’ll demonstrate how to use this simple way to create an ultrasonic sound generator.

This ultrasonic sound is audible to humans between 1 Hz and 20 kHz. We know that sound frequencies higher than 20 kHz are referred to as ultrasonic. Animals that can hear this ultrasonic sound include dogs, cats, insects, mosquitoes, and bats.

Below is a step-by-step tutorial for creating an ultrasonic sound generator with an IC 555 timer.

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Ultrasonic Sound Generator Using 555 timer

Circuit Schematic

Ultrasonic Sound Generator Using 555 timer


  • 555 Timer
  • 0.1 uF Ceramic Capacitor
  • 220 Ω Resistor
  • Piezo Buzzer
  • Switch
  • 5V Power Supply
  • Breadboard

Circuit Connection

Initially, we’ll place a 555-timer integrated circuit on the breadboard. Next, we will join pins 4 and 8 together and connect straight to the Vcc terminal in accordance with the circuit schematic. Additionally, attach pin 1 directly to the power supply’s ground terminal.

We’re going to put a 10 KΩ potentiometer directly on the breadboard. Next, its left terminal will be linked to IC pin 7 and Vcc with a resistor value of 1 KΩ, and its right terminal will be connected to IC pin 2.

Subsequently, IC pin 2 will be used to attach a tiny 0.01 uF capacitor (code 104) to the ground terminal.

Lastly, pin 3 of the IC will be used to connect a piezo buzzer, and another terminal will be linked directly to the ground.

Working Principle of Ultrasonic Sound Generator

The IC 555 timer in this project’s ultrasonic sound generator runs when the switch is closed. According to the circuit schematic, the voltage at the threshold and trigger pin will both be 0 at first since the capacitor’s voltage will be zero.

At a certain point, the voltage at the threshold pin is less than the voltage of the capacitor as it charges through potentiometer R1 and resistor R2. The timer’s output changes as a result.

At this point, the capacitor begins to discharge through resistor R1. As a result, the output signal has an oscillating frequency of 22 kHz.

This ultrasonic sound generator circuit drives a frequency of 22 kHz with its output. A tiny piezo buzzer will be used as a transducer to obtain output.

Applications of Ultrasonic Sound Generator

  • It can be used to measure the distance of an object far from the sensor.
  • Ultrasonic sensors can detect motion sensitivity by reflection of signals of ultrasound.
  • We can use it as a pest or animal repellent from a specific area.
  • Can measure liquid in tanks or containers using ultrasound.

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