piezoelectric spark generator?

henry99

I've been searching high and low but haven't been able to find any spark generators that can be controlled by the basic stamp. I want to make a programmable ignition for my bbq. I was thinking about using a car sparkplug but then I realized I need a high power ignition coil. Are there any low power piezoelectric solutions someone can suggest? I figure cell phone vibrators use piezoelectric circuitry and maybe I can adapt something like that to generate a spark. Has anyone seen interface circuitry to piezoelectric vibrators? Thanks for any leads!

Jonathan

Might be easier to use an ignition coil. The old model T versions (still available) have a built in vibrator IIRC. You can make a vibrator from a relay, it won't last too long in continous duty, but would probably work OK for occasional lighting of a BBQ. If you use an ignition coil, be warned that most spark plug wire and spark plugs are resistive, so you will lose some power.

You can also power a regular ignition coil with 120VAC with a dimmer, or you can make a push/pull transistor driver. You could also make a Marx generator or use an oil burner ignition coil.

Be warned that there are inhernent dangers in paying with HV, personal injury and starting fires among them. Using any of the methods outlined above would NOT be UL approved and would have to be considered a "mad scientist" approach.

However, it seems like the piezo's found in a modern stove could be made to work, but I have no idea other than salvaging one off a stove or ordering one as a replacement part. I assume they are powered by the mains voltage but I have never messed with one. However, they would be safer.

Out of curiosity, why do you want a programmable ignition? I hope not to start it when you aren't around. If that is it, I would look into a more conventinal ignition system with a pilot and thermocouple. If you play with any of the methods I mentioned above, I would use an optpisolator to drive the ignition. Just remember that you are playing with high voltage and flammable gasses.

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MSDTech

Piezoelectric igniters are not controlled electronically. The crystals used in piezo devices are two way transduces that convert mechanical energy and electrical energy. The piezo speaker in the Basic Stamp kits converts electrical energy into mechanical energy to vibrate the air and make sound. Piezo igniters work in the other direction. They usually have a spring loaded hammer that strikes the crystal, causing it to produce a short high voltage pulse which is connected to the spark gap.

Jonathan

All very true. But the ones on stoves must have small actuators that are controlled/driven by the mains voltage, so they *should* be controllable in some fashion. While I haven't played with one, none of the ones I see work when the power is off, nor does the user have to push or actuate anything, just turn the knob.

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Beau Schwabe

henry99,

I would think you might have better luck in reverse engineering a disposable camera's photo flash circuitry than a piezo igniter.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Jonathan

Beau,

All the disposable cameras I have taken apart run at about 300V, not enough for reliable spark generation. Are there some out there that output more? If so what brand, I need one. [noparse]:)[/noparse]

However, with a disposible camera flash supply, modified to limit the current and connected to an old "Operation" game makes for a challenging party game. [noparse]:)[/noparse]

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Beau Schwabe

Jonathan,

"All the disposable cameras I have taken apart run at about 300V" ... Yes, that voltage goes across the Xenon tube... The trigger voltage for the Xenon tube will take that 300V into the kV range to initiate the flash. The high voltage trigger coil connects to the "third" terminal on the Xenon tube located on the outside glass portion of the tube.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Jonathan

Wow, I didn't know that! Now I'm going to have to go and play with one! I have only used them to power Nixie tubes and shock people. Muhaha, off to dig one up and play. Thanks for the info!

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www.madlabs.info - Home of the Hydrogen Fuel Cell Robot

henry99

Beau:
Thanks for the lead! I found this site that uses the disposable camera http://www.angelfire.com/80s/sixmhz/camera.html

Runs off a single AA too!

My bbq lighter is going to be sweet!

stephenwagner

The Broilmaster BBQ grill has a unique 1.5 volt AA cell igniter that creats a spark over a 1/4 inch at a rate of 4 sparks a second.

It is item 17 of the of the attached link.

http://dev.obatadesign.com/clients/Broilmaster/pdf/P3P4.pdf

Broilmaster P/N B072218.

It is available here for $23.00.

http://broilmaster2002-store.stores.yahoo.net/igniters.html

I am sure you can hack somthing for your application.

The HIGH VOLTAGE wires are thick insulation about 9 in. long each. It also stands up to the high heat application under the grill. I have used mine for 8 years. The unit has never faild or even cracked and the wires are still flexable.

Stephen Wagner

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