# Ignition coils?



## keeperofthegood (Apr 30, 2008)

Hey oh

Guys, I am wondering. What is the smallest ignition coil going that does not need an external magnet to activate it? Length X Width X Height size I mean. 

This is related to pedals as I "have an idea" and using an ignition coil is part of that idea. Actually, what I need is a spark. Something under 1mm in length would work fine I think. I tried a dozen small body transformers last night, but none had enough emf to jump a spark. I did see some online plans for a coil-less ignition system, but the level of construction failed my KISS principles 

The coil idea may be a fail for cost though, I had a look at eBay and it seems marine ones (that look small in the pics) run around 70 dollars. I am not wanting to spend more than 20 or 30 on the idea unless it actually works.

So, I'm open to ideas, suggestions, places to scrounge


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## Fader (Mar 10, 2009)

What about the ignition from a BBQ?
You'll see a lot of those being tossed out this time of year.


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## keeperofthegood (Apr 30, 2008)

Ah the impact piezo types? Easy to pull from lighters too. What I have in mind would need continual spark. A means of containing in a pedal this effect (without the need for well... stage effects XD) I tried modelling the wave form and then mix/mod in audacity, and a stable wave wont do it. The random ionization of air is what adds the growl I think. So, a spark is needed. Not sure which way it would work best, to modulate the spark directly by the guitar, or to use the spark 'noise' to modulate the guitar. This is just in the "crazy idea" stage, no idea how far I will go with it 

[youtube=http://www.youtube.com/watch?v=qEG-1iYpgKU]qEG-1iYpgKU[/youtube]

The actual growl can be eliminated too, with the proper setup and these can be good(ish) speakers (not a lot of bass response from what I have so far seen).

[youtube=http://www.youtube.com/watch?v=1fGjk_BE0lA]1fGjk_BE0lA[/youtube]


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## greco (Jul 15, 2007)

keeperofthegood said:


> This is related to *pedals *as I "have an idea" and using an ignition coil is part of that idea. Actually, what I need is a *spark.* Something under 1mm in length would work fine I think.


Now I am really curious.

Hope the BBQ ignition idea that *Fader* suggested has potential.

Dave


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## ajcoholic (Feb 5, 2006)

I have been a model airplane nut since I was a kid. I have also had an interest in antique model engines, and it so happens that a lot of engines from the 30's, 40's and 50's were spark ignition.

You can still purchase small ignition coils to run these (I have a few) and they sell for about $20 US.

Not very common, but you can get them at specialty model suppliers.

Here is one:

http://www.woodysengines.com/assets/pdfs/informational.pdf

what you want is called a "modelelectric coil" and is about the size of a "C" cell.

I may have a spare one I can sell you if interested but I have to check.

Try ebay as well, but make sure you are buying a new one, as a lot of the old vintage coils are deteriorated to the point they will have internal shorts.

AJC


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## ajcoholic (Feb 5, 2006)

also, an ignition coil is just that, a means to produce a high voltage spark. It will always rely on something to energise it and then make/break the supply current - the resultant collapsing mag field within the coil induces the high voltage which creates the spark (rough description).'

A magneto uses a rotating magnet to energise the coil.

A small coil like I described, generally uses a 3 or 4 volt power supply, and a set of points to open and close the input power supply (along with a capacitor, which reduces the arcing at the points). Or, a modern system which consists of a transitorised trigger can be used (still with points).

A totally solid state system is also available, as which is used for modern model aircraft engines. This is a coil, and computer controlled ignition which is triggered by a magnet and hall effect sensor. Still requires something to move the tiny magnet past the hes to trigger the ignition.

To get a continuous ignition spark, you may need to look into a "buzz" coil, like they used in old model T cars. Basically kept the ignition coil firing continuously... but remember also that the resultant emf of a spark will cause a lot of noise around a guitar or amp.

If you do a search on model engines/ ignition systems/buzz coils you should find something. I must have this stuff in some of my engine books as well.

AJC


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## Fader (Mar 10, 2009)

Arcs and sparks are not friends of the soundman.


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## keeperofthegood (Apr 30, 2008)

Hey guys, thanks for the replies so far. Yes, arc noise is nasty  











Through the magic of photoshop, this is what I had in mind for blocking the transmission of noise, and encapsulating the spark safely. I would need to use an scr or other actuator that is solid state to energise the coil I would think so that part of the circuit was noiseless.

A - the power "in", and C - system ground. This would be important when adjusting the gap.

B - the signal out.

D - I went looking on google but didn't find, though I have seen in shops years back, but there are bushing sleeve capacitors that are meant to RF seal metal boxes. I don't have any idea on the electrical breakdown of these. I know for the B out leads they would work fine.

E - just some 3/4 inch or so household copper pipe and end caps as in the fun google picture I used.

F - Something like glass or ceramic (the spark is hot) tube that is used as a coil form.

G - The coil XD I think 2 or 3 layers of #20 or #22 wire would suffice for this.

H - The spark gap, adjustable by the screw.

:/ This is what popped into my head last night, and I've been mulling it over a lot since. Only way for me to really tell if it would or would not work is to try it, though I am sure there are engineeres and other hobiests here that could see 1000 problems in the idea.

**edit The "waveform" of energy across B I think "should" be an image of the spark. If I could evacuate the tube a bit to increase the randomosity of the sparks jump rate/path that should also help to follow the tesla discharge model. The spark's frequency would be set by the coil timing, then the guitar would mod that signal and amp from there in the same manner as how it would work in driving the tesla on/off I think. No information on this idea on google from the looking I did yesterday


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