Is the output of my ignition coil AC?

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Discussion Overview

The discussion revolves around the output characteristics of ignition coils, specifically whether they produce AC or DC voltage. Participants explore the implications of using ignition coils in high voltage applications, including their suitability for powering devices like Cockcroft-Walton multipliers. The conversation includes technical details and varying interpretations of the output waveform.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Max questions whether the output of an ignition coil is AC or DC, citing confusion from an illustration suggesting DC output.
  • Dave suggests that the output is likely pulsed DC, produced by the ignition system.
  • Old Jim references a source indicating that ignition coils produce unipolar pulses, which may exhibit ringing or decaying sinusoidal oscillations.
  • Old Jim further explains that the output consists of a transient waveform with damped AC and decaying DC components, arguing that the video Max referenced oversimplifies the output characteristics.
  • Max seeks clarification on how to select components for a Cockcroft-Walton multiplier based on the ignition coil's output.
  • Participants express concerns about safety when working with high voltage systems, emphasizing the need for skill and caution.
  • Max states his intention to achieve high voltage outputs, estimating the performance of a six-stage multiplier based on the ignition coil input.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the ignition coil output is AC or DC, with multiple interpretations and models presented. The discussion remains unresolved regarding the exact nature of the output waveform.

Contextual Notes

Participants acknowledge the complexity of the output waveform, which includes both AC and DC components, and the implications for practical applications. There are concerns about the safety of working with high voltage systems, which may limit the discussion's scope.

Who May Find This Useful

Individuals interested in high voltage applications, ignition coil functionality, and those working on projects involving voltage multipliers may find this discussion relevant.

eigenmax
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Hello,
I am working on a project that requires both high voltage AC and DC.
I was going to use an ignition coil for the AC because I thought it's output would be AC, but when I saw this illustration, https://www.google.ie/url?sa=i&rct=...cH4F28DNcL3AnRFD_vluFa7A&ust=1498033191615843 , I got confused. It shows the output to be DC.
If powered as is shown in the illustration, is it AC or DC?
Thanks ,
Max
 
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eigenmax said:
Hello,
I am working on a project that requires both high voltage AC and DC.
I was going to use an ignition coil for the AC because I thought it's output would be AC, but when I saw this illustration, https://www.google.ie/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwialOTp_svUAhVEC8AKHfLKDGAQjBwIBA&url=http://www.sciencemadness.org/talk/files.php?pid=91557&aid=2775&psig=AFQjCNFF2-cH4F28DNcL3AnRFD_vluFa7A&ust=1498033191615843 , I got confused. It shows the output to be DC.
If powered as is shown in the illustration, is it AC or DC?
Thanks ,
Max
I would expect it to be pulsed DC ... the pulses being produced by the points / CDI or what ever other system is utilisedDave
 
davenn said:
I would expect it to be pulsed DC ... the pulses being produced by the points / CDI or what ever other system is utilisedDave
Ok, thanks. Finally, so if it is pulsed DC, I expect it won't be able to power a Cockcroft-Walton multiplier?
Thanks,
Max
 
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html shows that yes, you should get unipolar pulses out of your coil . But it might 'ring' ie decaying sinusoidal oscillation , unlike the clean pulse in the hyperphysics images.


Your link redirects me to here - is that correct ?
http://www.sciencemadness.org/talk/files.php?pid=91557&aid=2775.

upload_2017-6-20_9-23-46.png


Is that a Model-T Ford spark coil ? Looks like it'd buzz and make continuous stream of pulses.

If your multiplier capacitively coupled(as in this wikipedia link) it won't mind the DC content at its input.
https://en.wikipedia.org/wiki/Cockcroft–Walton_generator
The CW is a voltage multiplier that converts AC or pulsing DC electrical power from a low voltage level to a higher DC voltage level.
old jim
 
jim hardy said:
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html shows that yes, you should get unipolar pulses out of your coil . But it might 'ring' ie decaying sinusoidal oscillation , unlike the clean pulse in the hyperphysics images.


Your link redirects me to here - is that correct ?
http://www.sciencemadness.org/talk/files.php?pid=91557&aid=2775.

View attachment 205809

Is that a Model-T Ford spark coil ? Looks like it'd buzz and make continuous stream of pulses.

If your multiplier capacitively coupled(as in this wikipedia link) it won't mind the DC content at its input.
https://en.wikipedia.org/wiki/Cockcroft–Walton_generator

old jim
Thanks for replying,
I got the schematic to power my coil from . Yes, the image in the link is what I was looking at. Is the video correct in sating that it gives AC output?
Thanks again,
Max
 
eigenmax said:
Is the video correct in sating that it gives AC output?

We always want simple answers. But Mother Nature makes us work harder than that before she gives us understanding.

Interrupting current through the coil initiates a spark. That's always one polarity.

The capacitor allows "ring down" which is AC.


SparkWaveform1.jpg


Not trying to be obscure here, just precise.
It's a repeating transient waveform.
That transient waveform has two components - damped AC and decaying DC.

So your video is i would say oversimplified.

I think the truest answer is "Unipolar pulses with substantial AC components ".

old jim
 
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I understand now,
thank you.
 
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jim hardy said:
We always want simple answers. But Mother Nature makes us work harder than that before she gives us understanding.

Interrupting current through the coil initiates a spark. That's always one polarity.

The capacitor allows "ring down" which is AC.


View attachment 205822

Not trying to be obscure here, just precise.
It's a repeating transient waveform.
That transient waveform has two components - damped AC and decaying DC.

So your video is i would say oversimplified.

I think the truest answer is "Unipolar pulses with substantial AC components ".

old jim
Sorry, but as a final question, how would I choose Cockcroft-Walton multiplier parts based on the output of this setup? What capacitances, recovery times , etc ?
Thanks,
Max
 
eigenmax said:
Sorry, but as a final question, how would I choose Cockcroft-Walton multiplier parts based on the output of this setup? What capacitances, recovery times , etc ?
What voltage are you looking for ? High, if you're starting with an ignition coil.
What current ?

I'll defer to somebody who has more high voltage experience than i.
 
Last edited:
  • #10
Furthermore,

PF will want some assurance that you have the skill to build this thing safely.
With Ignition coils and high voltage capacitors you could easily build something that will blow a child's fingers off or electrocute an adult.
 
  • #11
jim hardy said:
Furthermore,

PF will want some assurance that you have the skill to build this thing safely.
With Ignition coils and high voltage capacitors you could easily build something that will blow a child's fingers off or electrocute an adult.
Yes, I can handle these systems safely, I assure you.
 
  • #12
jim hardy said:
Furthermore,

PF will want some assurance that you have the skill to build this thing safely.
With Ignition coils and high voltage capacitors you could easily build something that will blow a child's fingers off or electrocute an adult.
jim hardy said:
What voltage are you looking for ? High, if you're starting with an ignition coil.
What current ?

I'll defer to somebody who has more high voltage experience than i.
Well, the current is unimportant to me, but I'm putting in about 10kV from the ignition coil, through a six-stage multiplier this should create 120 kV ( please correct me if I'm wrong). Also, the third stage of the six-stage multiplier should output 60 kV, right?
Thanks,
Max

Mod note: Thread temporarily closed pending moderator action.
 
Last edited by a moderator:
  • #13
Thread is closed due to the dangerous nature of the discussion (and the level of experience of the OP).
 

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