Electronics > Beginners

Passive piezo buzzers

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queennikki1972:
I accidentally ordered passive Piezo Buzzers instead of Active. I have about 15 of them and they do not work with most simple circuits calling for a piezo buzzer. What can i do with them . I know they require AC signal to work, but I am not far enough along to play with AC yet other than transformers in power supplies.

alank2:
Are you playing around with microcontrollers?  You can connect a passive piezo directly to most microcontroller pins and then toggle the pins at different frequencies to make sound.  A trick to make it louder is to toggle both pins to the opposite polarity at the same time to make it louder.  For example, pin1=output low, pin2=output high, and then immediately change it to pin1=output high, pin2=output low.  Quieter could be leaving pin2 output low and then taking pin1 between output high and output low.

queennikki1972:
Thank you, Ill try that, hate to waste them.

Zero999:
Do the buzzers have two or three leads?

The three leaded variety are easier, as one transistor is all that's required.



The inductor variant is louder, but more expensive.

Otherwise there's the classic two BJT astable. D1 and D2 aren't needed if the supply voltage is below 6V.

queennikki1972:
They are 2 lead

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