The Old Standard Ignition System. Battery. Coil. Points. And Condenser....

[Magluvin]

Ok, I gota git.  If you are going to reply tonight try and make it one post and ill let it through tomorrow.  Wish we could see eye to eye here. But your just dead set on Im(were) wrong and will put up just about anything, even if it is clearly wrong and if that doesnt work you still insist im wrong with some other new inaccurate proofs

See ya tomorrow.

Mags

[MileHigh]

Here is the fundamental point:

Magnetic energy is being drained off from the core during the plasma burn.  So both the primary and the secondary will go to a high voltage during the burn-off.  Let's just use positive voltages to keep it simple.

So let's say the primary goes to 300 volts.
And therefore the secondary wants to go to 3000 volts, but in reality it is being clamped by the burning plasma, and let's say it's clamped at 500 volts.

During the entire draining of the magnetic energy in the core, the magnetic energy is going down, and therefore both the primary and secondary will remain positive, and what their positive potential will be at is based on the rate of the magnetic energy drain-off.

This means that the primary remains high at some potential, and only when the magnetic energy in the core drains to zero does the EMF disappear.  With the EMF gone, the charged capacitor does a ring-down with the primary, but the burn is over.  So the secondary swings during the ring-down, but it never ignites the plasma.

Now, I am suggesting that during this whole plasma burn process the battery is still pumping magnetic energy into the core, and that's the real source for the bigger and more robust spark.  Note that with the primary charging the capacitor, the capacitor no longer "eats" into the voltage drop of the primary relative to the battery as per my original posting.  So that implies that the battery puts more power into the core and extends the spark time.  It's not easy to make measurements when two things are happening simultaneously but it can be done.

One aspect of uncertainty is that the magnetic energy in the core has to drain to maintain positive potential on the primary, but if the battery is also adding magnetic energy during the burn, what's the deal with the net magnetic energy?  Does it still drain off but more slowly?

You don't have a victory, you can do whatever you want to do.  Like do a test and look for the plasma on and off ticks and relate the ticks other observations.  Make some energy measurements.  I am almost 100% certain you are not going to find your barely-defined resonance.  But what I am pretty sure you will find is that the battery pumped out X Joules of energy above any beyond the initial energy put into the core and these "above any beyond" X Joules of energy went into the more robust plasma burn.  i.e.; the plasma burn without the capacitor in place had Y Joules of energy.  The plasma burn with the the capacitor in place had (X+Y) Joules of energy.

You can't just say, "I think there is resonance making the spark bigger," you can't.  You actually have to provide a detailed coherent technical explanation and because even a simple circuit can be tricky enough, confirming your hypothesis on the bench is the real way to go.  All the indications are that there is no resonance.  There is a single continuous plasma burn with no changes in the current direction flowing through the plasma and when the burn is over the capacitor is charged to a certain potential and there is an innocuous ring-down that drains off the unused energy in the capacitor.

[MileHigh]

I have been fishing around online.  Now I am going to sort of play devil's advocate.

http://classicmechanic.blogspot.ca/2011/03/ignition.html

Here is a comment from somebody:

<<< Bingo! The condenser is connected across the points. When the points closs, the condenser voltage is clamped at zero, and current from the battery "charges" (via a building magnetic field), the primary side of the coil. When this is complete, the current flowing through the coil is now constant. When the points close ((MH:  He means open)), the condenser has two functions. One is to shunt the current which because of the collapsing primary coil sides magnetic field, wants to continue to flow, and would otherwise arc and quickly ruin the points. This probably wouldn't be a danger, because without the condenser, the ignition won't work. The condenser is charged up (voltage wise), by the current flowing from the coil because of the energy stored in the now collapsing magnetic field. This current flow quickly charges the capacitor, and then the capacitor then sends current back to the coil. This continues with each back and forth current swing being smaller. This is called wringing  ((MH: ringing)). The first cycle or longer (at a certain frequency), is what induces a corresponding (but higher) voltage and current that creates the spark at the spark plus. So the condenser protects the points from arcing, and allows a rapid and oscillating discharge of the primary coil, and that is necessary for generating a strong spark. Without the condenser, the spark would be weak or not even there. F on the schematic, F on the explanation.  >>

So, he thinks there is resonance and is basically confirming what you are saying.  So let's examine this more closely.

Would you agree that it's the core of the ignition coil that is the main energy storage component and the capacitor is not a major player in the energy storage?  You have made references to the "tiny capacitor" so I think that you would.

This guy says the cap charges up, and then rings down with the primary and you get a more robust spark.  If this is true then with your plasma sensor loop connected to your scope channel you would have to see a decaying oscillation.  This assumes the plasma stays "lit" the whole time as you get the ring-down that sustains the spark.  In other words, the ringing has to be fast enough such that the plasma stays lit the whole time.  If the plasma goes off and then on, that represents sharp on-off switching of the current and you should see a series of "ticks" on the plasma sensor loop.  Let's assume either way is perfecty viable.

Now here is the problem:  If there is a sustained but decreasing level of magnetic energy in the core then any ringing doesn't make sense.  The reason I am saying this is as follows:  Okay, the cap is charged to it's maximum voltage and it's time to change direction of the current flow.  Well, when the cap discharges into the primary, you will simply get magnetic flux cancellation inside the core with "north" annihilating "south."  So the capacitor would simply "magnetically short itself out" when it tried to reverse the direction of the current flow and discharge.  You would simply reduce the magnetic energy in the core by a chunk.

So what are we left with?  The only thing we are left with is that the capacitor can only reverse the current direction and "swing back" after the initial plasma burn is done and the core has been completely drained of magnetic energy.  And now you face a problem if you assume that the magnetic core of the ignition coil can store way way more energy than the capacitor, even when the capacitor is charged to 300 volts.  And note on the first "swing back" the capacitor has to do several things, 1) pump power into the core that is immediately burned off in the plasma burn, and 2) recharge the battery.  It really sounds like it's not going to fly.

So the conundrum is that the capacitor is "tiny" and is only really there to protect the points.  It's not supposed to be a big energy storage device to sustain three or five or ten "resonance cycles."

Here is a thought that occurred to me:  Is it possible that without the capacitor a hell of a lot of energy is burnt off in the points sparking when they open?  And then when you add the capacitor the elimination of the point sparking means you have more magnetic energy in the core and that's the reason you get a bigger spark?  I view that as a long-shot but you never know.

I still say the fat spark has to get its extra energy from the battery and that could be confirmed through measurements.

Again - there are lots of problems with the supposed resonance mechanism when you examine it.  And right now I am doing the thinking work that you are supposed to be doing.  I don't think you are thinking things through.

If you use a nice spring-loaded SPST switch like I said and then get nice consistent small sparks without the cap and nice consistent big fat sparks with the cap, then you can use the sensor coil near the HV output like I said.  If you get a decaying sinusoid during the fat sparks, or a series of fast ticks during the fat sparks, that would tell you right away that resonance is in play.  If you get a single "on tick" and a single "off tick" that would tell you that the plasma burn is a single unidirectional pulse of current.  One more time, you should be thinking of this stuff by yourself.

[MileHigh]

Still sniffing around.   Here is a clip that backs you up 100%.

https://www.youtube.com/watch?v=ZU87fpNQ3d8

HOWEVER, the "Automotive Engineering" channel might be much more automotive than electronics and it's possible that the persons that made the clip were just "following the crowd."

Going back to the "current has to keep flowing" angle relative to this clip:  Okay, the capacitor charges up to say 300 volts which lets the current flow, and then you are at the limit of the EMF generation and the current flow stops.  Why does it stop?  It actually stops because the secondary has just "bridged the gap" and ignited the plasma.  So then the magnetic core of the ignition coil dumps all its energy into the plasma.

So, suppose we guesstimate the energy status when the trigger point comes and the plasma ignites and there is 300 volts in the capacitor.  My guess is this:  90% of the energy is in the ignition coil core, and 10% of the energy is in the capacitor.

So when the core dumps all of its magnetic energy, the clip claims then you have a resonant plasma-firing ring-down.  I don't see it, what I see is just the ring down with no plasma generation.  So I think the clip is wrong and just "following the crowd."  I looked at several other clips that just say the capacitor protects the points and there is no mention of the the big plasma ring down.  But I am not convinced that those clips are the real thing either.

[norman6538]

As a young boy I was told that the purpose of the condenser was to prevents the points
from burning and that is one feature of Tesla's great circuit.
But what the spark plug needs is high voltage to jump the gap
and part of that comes from the primary secondary voltage increase
and part of that high voltage comes from the backemf which is greater than the
battery 12v which goes out of the coil and into the condenser where it gets
recycled again and again so the spark will jump the gap and get repeated
in the resonate circuit many times over.

If you hold your fingers on a 12v battery you will not get shocked but
if you hold each hand to a broken section of a wire and touch them
together and they are powering a coil or motor coil when you disconnect
them you will get shocked because of the backemf because its way over 12v
from the battery.

A very clever and very efficient circuit that works everyday for millions of folks
and for millions of sparks...

But the real question is can we get anything extra out of this circuit like the Bedini
school girl circuit other than the excellent spark we want?

Norman