high voltage trigger/ ignitor circuit

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cmh
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high voltage trigger/ ignitor circuit

Post by cmh » Wed Sep 03, 2003 9:17 pm

does anyone know of a circuit capable of producing a spark through a gap that is operated on 12vdc and is fairly small and inexpensive

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haklesup
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Re: high voltage trigger/ ignitor circuit

Post by haklesup » Thu Sep 04, 2003 11:17 am

How big of a spark and do you want to sustain it.<p>There are many ways to make a small spark but if you want a continuous arc you need a bigger circuit. Heck, just touching the 12V leads together should produce a small short duration spark<p>A diode doubler or tripler can generate very high voltages but usually not much current.<p>A square wave driven into a step up transformer with a high turns ratio (like a TV Flyback) will put out as much power as you put in as long as the components can hold up.<p>Whats your application?

cmh
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Re: high voltage trigger/ ignitor circuit

Post by cmh » Thu Sep 04, 2003 4:53 pm

i need a spark capable of lighting propane, so i need a continous spark because the propane will be on for several seconds and then shut off by a solenoid

Chris Foley
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Re: high voltage trigger/ ignitor circuit

Post by Chris Foley » Thu Sep 04, 2003 5:24 pm

You might get a spark coil from an older ('60s or early 70s) compact car. I suppose a coil might be considered a little big, but it's cheap and it'll definitely do the job. You can scrounge the HV wires and a few of the plugs along with the coil for 10 bucks or so at a scrap yard, and then you can then use the plug to light 'er up. The only other thing you might want is a special nut to mount the plug on a small aluminum bracket to complete the electrical connection. They cost about a buck at auto parts stores -- special thread, not usually available at the ol' hardware store. Spark plugs are practically indestructible for short term use. Good luck.<p>Chris<p>[ September 04, 2003: Message edited by: Chris Foley ]</p>

rshayes
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Re: high voltage trigger/ ignitor circuit

Post by rshayes » Thu Sep 04, 2003 8:41 pm

You might look at electronic ignitors foe oil furnaces. These appear to be an electronic circuit driving a high frequency step up transformer. Johnstone Supply (www.johnstonesupply.com) and probably hundreds of other distributors sell these units. They seem to put out about 30,000 volts AC at about a milliamp.<p>The primary circuit may need to be changed to operate off of 12 VDC. Possibly a transformer can be taken from a used or surplus unit and a new drive circuit designed. Designing and constructing the transformer is by far the hardest problem, due to the high output voltage.

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haklesup
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Re: high voltage trigger/ ignitor circuit

Post by haklesup » Fri Sep 05, 2003 10:21 am

A furnace ignitor makes a lot of sence especially when you consider that many come with a thermostat that senses that the flame has started. Consider hijacking an entire gas furnace control system and change the orifice for propane. Even better, look at propane heater control systems for RVs and Campers<p>The 110V problem is easily solved if the 12V supply is beefy like a truck power system or car battery. You can use a simple off the shelf inverter.<p>A low tech way would be to rig a pizeo electric BBQ starter button for repeated triggering. You could use a small electric motor with an eccentric cam which when rotated would push the ignitor button once per revolution. There are rotary type ignitors that can be easily adapted

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