• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Fun with car ignition coils? Or use : )

Status
Not open for further replies.

Cobalt60

New Member
Just doing some spring cleaning and I have come across 2 ignition coils out of an old Dodge Ram I used to have. I am wondering what I could use these for other than their intended purpose (auto use). One is the original, a normal sized one which says "oil filled" and indeed I shook it and it definitely had liquid inside. The other is an after market Accel "Super Coil" which is about 4 times the size and does not seem to be liquid filled.

So, these coils are designed to convert 12V DC into several thousand volts. However, in their original application, this is done in short bursts, so I am curious to know if they can run continuously, perhaps with cooling, modding, or a lower input voltage.

Well, if anyone can think of a use for these, Id love to hear about it. One use I can think of is possibly to make a high voltage power supply (hopefully able to sustain the voltage). But I dont need to necessarily make something useful, perhaps something just fun or decorative.

Also, are these efficient? And should I keep that oil filled one or just toss it?

Thanks!

-Chris P
 
Last edited:

Hayato

Member
Yes you can do a HV supply with those.
The problem is that ign. coils works better with low frequency pulses, they start to lose power after about 5~10 kHz, so their sparks are very audible.

You have one that is oil filled, that one will have a better thermal and insulation characteristics, but worse mechanical, if it falls it can spill the oil all over.

The other one can be filled with tar or epoxy, they are good too, but once it internally arcs, a conductive "carbon path" is formed within the tar or epoxy... And you'll lose power.
 

Hayato

Member
Yes you can make a similar one.

Tesla coils runs in hundreds of kHz to some MHz, that's why you have those spaks going everywhere "in the air".

With the ign. coils, you'll have to make some sort of spark gap to get those sparky effects, and the neon light will not light up due the low frequency (or it will bright very very weak).
 

Cobalt60

New Member
I dont need anything fancy, just some decent volume to the music and a nice little spark show (at least should be bright in a dark room). A longer arc would be much preferred. So, what do you think? Can I make music with an auto ignition coil, with a decent length arc?
 

Hayato

Member
Well, the biggest spark I could get with those coils was about 2 inches, running with a pulse every 0.5 second. (with a generic coil)

With an Accel/Mallory you may get bigger ones.

With music, to get some audible thing, you will work with frequencies between 100 Hz ~ 10 kHz, to reproduce a 10 kHz sound, you gonna need to run your coil at least at 22 kHz.

I don't remember what frequencies I worked with, but I believe that your spark will be limited to about 1 inch, maximum.
I can test the frequency tomorrow.
 

Hayato

Member
Another thing, you'll work with pulses, and pulses spectrum carries audible frequencies, so it's very probable that your audio becomes very noisy, even working with ultrasonic pulses. But it worths a try.
 

Speakerguy

Active Member
Very very doubtful. Sorry to say it. But ignition coils will only work very poorly if you are trying to get audio out of them like with a tesla coil. Your Dodge probably had a 6000RPM redline on a V8, so do the math on how often they were meant to be fired in a real world application. You can easily get maybe 1kHz out of it, but it won't be near 22kHz. The highest rep rate I've ever seen was with a drag racing coil that would go up to 10kHz but by then it was getting quite weak.
 
Last edited:

Diver300

Well-Known Member
Most Helpful Member
Drive the coil from the mains via a lamp dimmer and a small capacitor. Make sure everything is fused and that the capacitor is rated to the mains voltage.

You won't get music but you will get some good sparks.
 

tcmtech

Banned
Most Helpful Member
Here is a basic mains powered ignition coil driver. If you take the diac that triggers the SCR and put a opto coupler SCR IC in series with it then you could vary its firing rate remotely from an audio source being fed to the opto IC. ;)

The diac can actualy be a simple neon indicator lamp. They work great for this type of circuit triggering.

I may be crude but it will give you a varying spark rate! :)
 

Attachments

Hayato

Member
Well, I made some tests:

I tried 3 frequencies at high duty-cycle, to reproduce the dwelling angle of the contact breaker, as the breakers remains closed most of the time (they only open when the rotor cam lobe hits the contact breaker arm).

Well, some time ago I had done those tests, as I was playing with a multi-spark ignition, but I lost my notes somewhere.

Well, like Speakerguy said, I could achieve 22 kHz. This can be proved with some engine math:
If I have a V8 with max RPM = 6000, I know that each turn on the flywheel has 4 power strokes.
Well, 6000 rpm = 100 rps = 100 Hz. But I have 4 power strokes so 100 x 4 = 400 Hz.
In a normal contact breaker engine, w/o multi-spark, the ignition coil would run at 400 Hz, but the engineer that projected the coil is a pessimist one, and he would project a coil that would operate well until 4 kHz.

Well, the tests results:

2.577 kHz, good spark, 15mm long (~19/32 "), D.C. =~ 97,86%
4.300 kHz, usable spark for a spark plug, 5mm long (~3/16 "), D.C. =~ 97,00%
9.689 kHz, minimun spark, 1,5mm long (~1/16 "), D.C. =~ 96,70%

The frequencies and duty cicles were measured with a oscilloscope.

Well, you could use the 4.300 kHz to modulate some sound, just for fun.
 

Cobalt60

New Member
Hehe thanks for the info guys. Yeah maybe I wont try to get audio from this then : ( Maybe just some sparks. Basically if I cant think of a use for these things Im pretty much just going to toss them, though a 15mm spark may be good enough to at least try it out. But yeah any chance this thing can be used for continuous voltage? Or any other project ideas?

Oh and what about getting longer sparks with a much lower frequency?
 
Last edited:

Hayato

Member
There is no miracle, the biggest is about 1 inch. At 10 Hz, maximum.

A good way to get nice sparks is from an old TV flyback.
 
Last edited:

Cobalt60

New Member
Just running some ideas...

I think a spark would make a nice light source (in the dark anyway, for special occasions), but am guessing it would be quite noisy. So, I thought, what if it was in a vacuum (clear plastic enclosure)? That should make it relatively quiet right? But then what would happen to the spark?

I just got most of my tools and work space put together so I am just looking for some projects.
 

Hayato

Member
In a vacuum, it would work nice. If you take a tube and pull the air out, then the remaining gas inside is nitrogen, mostly, so your tube will bright some kind of violet. But like the spark, it will source some UV (ionized Nitrogen produces UV), as well, but I do not know the amount of UV.

If it is a open-air spark, like you said, it will be very noisy, and it will produce Ozone, which is toxic.

The glowing tube would be nice.

What is a spark? It is a ionized gas path which conducts current. Ionized gas has low impedance to electricity.

In real world, a complete vacuum is nearly impossible, so there is always remaining gas molecules inside the "vacuum".
With a little molecules of gas, it is much more easier to ionize and create a path for the electricity, that's what happens (it's almost the same thing - it's a "controlled" spark).
 

tcmtech

Banned
Most Helpful Member
If you want to make a basic spark tube just the tube out of a mercury vapor or metal halide bulb. With the low input current they will never get hot enough to hurt anything or even get to the point of normal operation. They just make neat little blue/white spark flashes!
 

GonzoEngineer

New Member
There is no miracle, the biggest is about 1 inch. At 10 Hz, maximum.

An interesting phenomenon to observe........make the spark gap out of two wires in a V shape. As you vary the frequency, the spark will move up and down the gap. We called them "Jacob's Ladders" when I was a kid.

They get real loud when the spark frequency finds its resonant gap......
REALLY LOUD!:D
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top