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Buzzers and Sounders



These do not generate their own sound. A separate circuit like an Astable is needed. An audio power amplifier might be needed.


Buzzers convert a Direct Current into a buzzing noise. This can be anything from an unobtrusive warning sound to a deafening noise designed to be heard in very noisy environments.

Some are semi-mechanical. Others use an oscillator circuit to produce an AC signal. This is used to drive a transducer that converts the AC signals into sound energy.

In all cases the sound is produced by a vibrating surface that creates pressure waves in the air (sound).

The vibrating surface can be made of quartz, using the piezoelectric effect or a moving coil can vibrate a paper cone (a loudspeaker).

A bell is a special case. There is a vibrating clapper which strikes the bell.

Designing Sounder or Buzzer Drivers

  1. How loud does it need to be? This is measured in dB, decibels with a sound level meter and it needs to be louder than the background environmental noise.
  2. What voltage does it run on? Check out the data sheet. Test it with a multimeter.
  3. Is AC or DC needed? Check out the data sheet.
  4. How much current flows through the buzzer so what kind of transducer driver do you need? Measure the buzzer current with a multimeter.
  5. Is the device inductive (does it use an electromagnet)? If so, the transducer driver circuit must be protected against Back EMF.




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