Is the output of my ignition coil AC?

In summary, the conversation discusses using an ignition coil for a project that requires high voltage AC and DC. The individual was initially confused about the output of the ignition coil, but it was clarified that it produces pulsed DC. They also discuss using a Cockcroft-Walton multiplier with the setup and the potential risk of working with high voltage components. The individual is looking for advice on choosing the appropriate parts for the multiplier. The conversation ends with a clarification on the expected voltage output of the multiplier.
  • #1
eigenmax
58
12
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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  • #2
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
 
  • #3
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
 
  • #4
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
 
  • #5
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
 
  • #6
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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  • #7
I understand now,
thank you.
 
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  • #8
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
 
  • #9
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).
 

1. Is the output of my ignition coil AC?

Yes, the output of an ignition coil is typically AC (alternating current). This means that the current flows in both directions, constantly changing in magnitude and direction.

2. How can I tell if the output of my ignition coil is AC or DC?

You can use a multimeter to test the output of your ignition coil. Set the multimeter to measure AC voltage and place the probes on the positive and negative terminals of the coil. If the reading fluctuates and changes direction, then it is AC. If the reading stays constant, it is DC.

3. Why is the output of an ignition coil AC instead of DC?

An ignition coil uses a step-up transformer to increase the voltage from the battery to a level high enough to create a spark in the spark plugs. This step-up process is achieved through the use of alternating current.

4. Can the AC output of an ignition coil be converted to DC?

Yes, it is possible to convert the AC output of an ignition coil to DC using a rectifier. However, this is not recommended as it can cause damage to the ignition system and decrease its efficiency.

5. What is the typical AC output voltage of an ignition coil?

The AC output voltage of an ignition coil can vary depending on the make and model of the vehicle, but it is usually around 20,000 to 40,000 volts. This high voltage is necessary to create a spark in the spark plugs and ignite the fuel in the engine.

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