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small but loud buzzer problem

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_hu_

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Hi
help needed,

I need a simple circuit to drive a piezo buzzer (the buzzer in not autoOX) with a pic. I build a pic based Vibration sensor that is Supplied by 3V litio cell, I need to produce a loud (long distance udible beep-beep) the pic produce a variable bf signal 800 Hz to 3000Hz, I just try to use a steep-up MC34063A with poor result ad large pcb (2 square cm of pcb only for the inductor).

thx in advance

_hu_
 

flatulent

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try a bridge

Try a bridge circuit using CMOS type inverters. Drive one side with a true signal and the other with an inverted signal. This in discrete transistor form is called an H bridge. Use square waves.

Adjust the drive frequency for maximum sould level. These emitters are narrow band devices.

An audio transformer can be used to raise the voltage by putting the larger turns side to the buzzer and the low turns side to the circuit described above.
 

mr_ghz

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Perhaps it's easier to use a piezo with integrated oscillator? They are
very loud and need only a supply-voltage of 5V and about 20mA...

Bye
 

_hu_

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@ flatulent
I'll give a try to your H bridge solution,
also now I'm triying an auto-trasformer solution..

@ mr_ghz
integrated oscillator bring the heavy limitation of the fixed freq. sound
i need a variable freq sound output.

thz for reply...

other Hint's are welcome
_hu_
 

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