Buzzer inside details

[rajaram04]

Sir what is present inside a buzzer actually ?
is it simple speaker or additional circuit or what ?

In some circuit diagram when i replaced buzzer with a simple piezo speaker or a small speaker it didnt work . . .

 

[tpetar]

Usually buzzer is piezoelectric element.

 

[rajaram04]

Usually buzzer is piezoelectric element.

kk sir that i know but only that element is present inside ?
i used dat device openly but its not working

 

[betwixt]

A Piezo element will not produce a tone by itself. The older mechanical buzzers used a switch and coil rather like a relay but the switch was in series with the coil and normally closed. When voltage was applied, the current flowed through the switch, energized the coil and opened the switch. Without power, the coils magnetic field collapsed, the switch closed again and started the cycle over again. A diaphragm was attached to the switch to make the sound of of it opening and closing louder.

In modern electronic buzzers there is usually a piezo element and a small transistor oscillator. The oscillator pulses voltage across the piezo elelment making it flex back and forth to produce the sound. The casing and outlet hole is tuned to the oscllator frequency to make it resonate and sound louder.

Brian.

 

[rajaram04]

A Piezo element will not produce a tone by itself. The older mechanical buzzers used a switch and coil rather like a relay but the switch was in series with the coil and normally closed. When voltage was applied, the current flowed through the switch, energized the coil and opened the switch. Without power, the coils magnetic field collapsed, the switch closed again and started the cycle over again. A diaphragm was attached to the switch to make the sound of of it opening and closing louder.

In modern electronic buzzers there is usually a piezo element and a small transistor oscillator. The oscillator pulses voltage across the piezo elelment making it flex back and forth to produce the sound. The casing and outlet hole is tuned to the oscllator frequency to make it resonate and sound louder.

Brian.

kk sir nice one it is thanks . . would you please have me a circuit diagram for oscillators in modern buzzers ?

 

[betwixt]

Sorry, I can't draw schematics while connected to Edaboard on a mobile phone!

Designs vary but many use a tapped inductor. The tap goes to the positive pin, collector directly to one end and the base through a resistor to the other. The piezo goes across the collector to tap side of the inductor and a capacitor goes from the base to emitter. The emitter is the negative pin. So it uses the inductor and capacitor to provide the necessary phase shift for it to oscillate.

Brian.

 

[rajaram04]

Sorry, I can't draw schematics while connected to Edaboard on a mobile phone!

Designs vary but many use a tapped inductor. The tap goes to the positive pin, collector directly to one end and the base through a resistor to the other. The piezo goes across the collector to tap side of the inductor and a capacitor goes from the base to emitter. The emitter is the negative pin. So it uses the inductor and capacitor to provide the necessary phase shift for it to oscillate.

Brian.

kk sir this much info is enough for me but tell about inductor value please . .

 

[Audioguru]

Here is the schematic of a modern piezo beeper. It uses a piezo with 3 wires because one wire provides positive feedback to the transistor's input to make an oscillator:

 

[rajaram04]

Here is the schematic of a modern piezo beeper. It uses a piezo with 3 wires because one wire provides positive feedback to the transistor's input to make an oscillator:

okk sir i got that thanks let me go through it cause i am not getting these type of structure in market having 3 terminals

 

[Audioguru]

You cannot buy a piezo transducer with 3 terminals. Instead you buy the inexpensive piezo beeper that has it and an oscillator transistor built inside.
Most piezo transducers that you can buy have only 2 terminals and are used as a speaker.