• Everyone:
• Components
• Battery
• Bulb
• Buzzers
• Heatsink
• Inductors
• KU109
• Loudspeaker
• Microphone
• Motors
• Piezoelectricity
• Seven Seg
• Solenoid
• Thermal Switch
• Transformer
• Voltage Regulator
•  

Everyone

Buzzers and Sounders

• Top Row: Active sounders.
  • They generate their own sound.
  • These all need a DC power supply.
  • DC Driver / Buffer / Switch needed.
  • Left to right: Very loud - middling - middling - not so loud.
• Middle Row: Low power speakers.
  • Do not generate their own sound.
  • An audio power amplifier is needed to drive these.
  • A 64 ohm (left) and an 8 Ohm Speaker (right).
  • Pleasant sound quality.
• Bottom Row: Piezoelectric Sounders.
  • Do not generate their own sound.
  • These can be driven with a 555 Astable.
  • 2500 to 4500 Hz are typical frequencies.
  • Harsh sounding.
  • Very noticeable.

Sounders

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

Buzzers

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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