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ignition coil is now apart

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Dr. Shark

Mon Feb 20 2006, 11:52AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

I wonder how an ignition coil secondary would perform if one had a suitable EE ferrite core to put in on and use it as a transformer and not as an inductor. This would probably work much better than hand-wound transformers. Can you check what wire gauge the secondary is? It would be nice to get a ballpark value on the obtainable continous output power before actually attempting to build something like that.

Marko

Mon Feb 20 2006, 01:15PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I wonder how an ignition coil secondary would perform if one had a suitable EE ferrite core to put in on and use it as a transformer and not as an inductor.

Well it is a transformer already...

Putting ferrite core will help arcing but I dont know how beter is it for output as secondary aleready has thousands of turns and it is unneeded to increase magnetic flux.

And as secondary is oily its unpractical to put it on some kind of core.

Best operation is TC-like with sparkgap under oil, solid state driver or mot+sidacs is also good idea...

Dr. Shark

Mon Feb 20 2006, 01:55PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Nah, its not really a transformer, its more like an inductor. You have to feed it with high dI/dt pulses and you get sparks from it, not arcs. I bet the output of an ingnition coil could be much more impressive if driven as a transformer, since peak current would be low, so the average current could be much higher (think I^2 R losses). How would you like 1000W 50kV continous arcs?

Problem would be to get a suitable core, though.

Marko

Mon Feb 20 2006, 02:10PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Even when pulsed it operates like a low frequency (resonant) transformer.
I cannot be considered inductor in any way, it has primary and secondary also (that are just internally connected in one lead) and behaves completly like transformer.

In car it operates pulsing a capacitor that goes in resonance with primary (without it sparks are 1-2mm and barely visible). This gives a voltage rise (automobile ignition coil capacitors are rated 100V or more) and like transformer it is stepped up by turn ratio of coil.
Capacitor also saves contact from eroding but its actually not its primary duty.

If there is no capacitor 100V kick would discharge trough opening contacts and not charge capacitor, there is no resonance and energy is burned in contacts.

It can be also done very good driving it solid state, on low frequencies, or like tesla coil (actually the same as in car, just capacitor voltage is bigger and mechanical contact is substituted by spark gap or sidacs, tank cap must be large to keep frequency low)

Bad side is iron core that doesnt like high frequencies (we cannot get high wattage otu of it) at all and if we get rid of it lots of fun can be had with now air-cored secondary...

Dr. Shark

Mon Feb 20 2006, 08:18PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Well, I guess it depends on your definition of transformer and inductor. It is somewhere in between since it has a bit of mutual inductance, but also lots of leakage inductance. Somewhere I read the term "transductor" describing this. Lets not argue over that.

I tried to take apart my ignition coil too (I am a copycat), but it seems that it is not filled with oil but with pitch. Now I think I have to boil it to get it apart - my girlfried is not going to be happy if I do that in our kitchen...

Dr. Shark

Mon Feb 20 2006, 08:59PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

After softening the tar with boiling water, I could get the coil out of its case and crumble off all the nasty stuff:

I am surprised how little coil there is inside this huge can. Well, it was a BMW can, so I suppose it's german efficiency

Marko

Mon Feb 20 2006, 09:10PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

yep good secondary, if youn can get rid of that tar you could do something with it...
Then put it under oil and run as tesla coil, to see how good job have germans done :)

Dr. Shark

Mon Feb 20 2006, 09:37PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

Yup, managed to get rid of the tar with some white spirit. Now the problem is, how to get out the iron core? I dont want to rip it out since it is also the terminal of the HV output, and I dont want to damage the winding.

I am surprised how thick gauge the secondary is, Im sure its good for lots of current, even though the resistance measures 5kOhm.

FaLLoUT

Thu Feb 23 2006, 09:32PM

Registered Member #241 Joined: Thu Feb 23 2006, 09:13PM
Location:
Posts: 19

joe doh thanks for the close image of clean windings what thickness is the secondary and if you can tell me primary too....

Marko

Thu Feb 23 2006, 09:50PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

This is the primary what is shown. Secondary is inside next to the core, and wire is thinner but not hair-thin or so like in HF flybacks and such.

And if I see correctly does that wire on left, on the core look like secondary?
Both wires should be acessible as other output is connected to primary too...

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