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The Projects Forum Working on an electronics project and would like some suggestions, help or critiques? If you would like to comment or assist others with their projects, this is the place to do it.

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Old 08-13-2009, 09:12 PM
Cinatas Cinatas is offline
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Default Piezo speaker, how to make it buzz

Hello I am completely new to this whole electricity thing, but I found some old circuitry in the attic. I have what happens to be a piezo speaker, a circuitry that connects 9V battery but converts it to 5V(No idea why it was even built). A 555 chip and a transistor name starts with 2N-3904, and a bunch of resistors and a few buttons along with few LED and a potentiometer.
I tried connecting piezo directly to the battery, but all it does is during connection it just make a cracking noise and does not work, upon connecting battery to button and then piezo I was able to get crack/buzz from piezo each time I press the button.
Now I found out that it needs constant pulsating noise in order to make it buzz, but how would I go around in doing that?
By connecting 555 chip pin 1 to ground and 4 and 8 to the battery and pin 3 to piezo I managed to make it buzz. But is there a way to control volume?
And can I do the same using potentiometer? Any diagrams would be a huge help. Thnaks a lot in advance, I hope I can sart getting interested in electronics.
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Old 08-13-2009, 10:02 PM
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ELECTRONERD ELECTRONERD is offline
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There are different types of piezoelectric buzzers, some are capable of buzzing with DC connected to them but most need AC to power them. It sounds like you have an AC buzzer and that circuit is used to create the oscillations to make that buzzer go. Do you have a schematic of some kind? If so, that would be very helpful to determine what is wrong with the circuit. Although, it sounds like your taking out the circuit and just connected the battery to the buzzer which will not work. Since it appears to be an AC buzzer, if you apply DC to it, it will only make that crackling noise you mentioned; but if you apply AC it should work. I would make a simple oscillator circuit and then apply it to the buzzer. There are transistor oscillators, op-amp oscillators, and many other types of oscillators. Go online and search "Simple Oscillator Circuit" and you should come up with a gargantuan amount of results. Here is an oscillator circuit I found using the 555 timer:



Bill Marsden might have a better one. He is de' expert when it comes to the 555 timer.
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Old 08-14-2009, 02:11 PM
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The above circuit will work for an oscillator but the frequency matters to drive the piezo. You can add a volume control using a pot before the piezo.
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Old 08-14-2009, 02:38 PM
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Quote:
Originally Posted by jj_alukkas View Post
The above circuit will work for an oscillator but the frequency matters to drive the piezo. You can add a volume control using a pot before the piezo.
Yep, that's absolutely true. You can adjust the frequency for the circuit I suggested though.
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Old 08-14-2009, 03:38 PM
going_in_deep going_in_deep is offline
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Default doubt

may i know what actually "pot" is?? and how could it controls volume? and why do we have to place a volume controller before to the piezo?? what happens if we connect directly the piezo speaker to the 3rd pin of the 555 ic?
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Old 08-14-2009, 04:03 PM
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Quote:
Originally Posted by going_in_deep View Post
may i know what actually "pot" is?? and how could it controls volume? and why do we have to place a volume controller before to the piezo?? what happens if we connect directly the piezo speaker to the 3rd pin of the 555 ic?
A pot is abbreviated for a potentiometer; also known as a variable resistor. In schematics you'll see just a fixed resistor but a pot will have an arrow going inside with three ternimals. This means you can vary the resistance thus varying the current level. Varying the current will adjust the frequency. You know with the 555 timer how you have a capacitor and a resistor to set the on and off durations? Well the resistor value sets the time it is on I think, so you can adjust this value to obtain a different frequency.
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Old 08-16-2009, 03:09 PM
going_in_deep going_in_deep is offline
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thanku electronerd .....
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Old 08-16-2009, 03:18 PM
Søren Søren is offline
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Hi,

I'd recommend a cap before the piezo disk - a value of say 470 nF should do.
To make it as loud as possible (without using inductors), it will need to be run at its resonnance frequency.
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Old 05-30-2012, 04:07 PM
Teddy_Techno Teddy_Techno is offline
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I recently did a project that used a Piezoelectric Speaker, and I found this video helpful to get started:

http://www.youtube.com/watch?v=xJqDO...feature=relmfu
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