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Piezo question

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Piezo question

Unread postAuthor: Hubb » Tue Sep 04, 2007 9:27 pm

I was just wondering if a piezoelectric igniter could be used to supply current to devises instead of batteries.

Example: The piezo is wired into a camera circuit board to supply some current instead of a battery.
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Unread postAuthor: thespeedycicada » Tue Sep 04, 2007 9:31 pm

no i dont think so.Its essentially static electricity so you might just fry the circuit.
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Unread postAuthor: Blackett » Tue Sep 04, 2007 9:34 pm

I managed to break one and wanted to take it apart, and in doing so i noticed a lack of wires and only some kind of yellow plastic core. Anyone know what this is?
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Unread postAuthor: thespeedycicada » Tue Sep 04, 2007 9:37 pm

i dont think the core youre talking about is plastic it might be the ceramic that creates the charge.
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Unread postAuthor: jimmy101 » Wed Sep 05, 2007 9:53 am

The core is ceramic or quartz, the only wires in a piezo are the ones that are connected to the top and bottom of the crystal. Smack the crystal and it generates a voltage across it's two ends.

It would be possible, but very inefficient, to use a typical piezo sparker to power a device. The output of a BBQ piezo is several KV at very low current. To get that down into a useable voltage range you would need a step down transformer (which is easy enough to do).

The voltage pulse from a BBQ piezo only last for something like 0.001 second. To make use of that short pulse you would need a way to save the energy (after you've stepped down the voltage with a transformer). So, connect it to a capacitor as the energy storage device.

So, lets see, a 100:1 step-down transformer and a 50V or so high capacitance cap (perhaps 100uF), click the piezo many times and measure the voltage that is built up on the cap.

Ooops, forgot one thing, the transformer will produce both a positive and negative voltage spike from the positive voltage spike of the piezo. So you need a diode in series between the transformer and cap to keep the negative spike from canceling out any voltage that the positive spike stored in the cap.
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Unread postAuthor: paaiyan » Wed Sep 05, 2007 9:55 am

jimmy101 wrote:The core is ceramic or quartz, the only wires in a piezo are the ones that are connected to the top and bottom of the crystal. Smack the crystal and it generates a voltage across it's two ends.

It would be possible, but very inefficient, to use a typical piezo sparker to power a device. The output of a BBQ piezo is several KV at very low current. To get that down into a useable voltage range you would need a step down transformer (which is easy enough to do).

The voltage pulse from a BBQ piezo only last for something like 0.001 second. To make use of that short pulse you would need a way to save the energy (after you've stepped down the voltage with a transformer). So, connect it to a capacitor as the energy storage device.

So, lets see, a 100:1 step-down transformer and a 50V or so high capacitance cap (perhaps 100uF), click the piezo many times and measure the voltage that is built up on the cap.

Ooops, forgot one thing, the transformer will produce both a positive and negative voltage spike from the positive voltage spike of the piezo. So you need a diode in series between the transformer and cap to keep the negative spike from canceling out any voltage that the positive spike stored in the cap.


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Unread postAuthor: jackssmirkingrevenge » Wed Sep 05, 2007 10:08 am

jimmy101 wrote:Smack the crystal and it generates a voltage across it's two ends.


On an unrelated note but you got me thinking, the mechanism that does the smacking could be lifted from the ignitor and used to smack open the schraders that I use to actuate my mini-pistons, hmmm...
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Unread postAuthor: dongfang » Wed Sep 05, 2007 3:37 pm

Hi

If you want to generate low voltage electricity from stuff moving, use a magnet (those you can pull from hard disk drives are really powerful) and a coil...

Regards
Soren
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