Technical Ignition coil ground ?

A DC signal can have varying amplitude. AC doesn't have a monopoly on that....

 

Coils are probably the toughest thing in an ignition system! I’m not saying they don’t go bad, but I will venture a guess that of all the coils replaced about only 15% were actually “ bad “! Cleaning the connections while changing probably fixed most of the problems. Just my experiences! Now with this new china ****..... the % is going to go up!






Bones

 

The Pertronix II is notorious for ignition issues. Everyone I've heard about used an auto trans. Pertronix I seems to have less issues. Put the points back in and see what you got.

 

Got it fixed.

switched over to a pertonix II with Lobe Sensor and swapped in a new .6 OHM coil.

problem fixed.

Feel free to continue debating the coil ground topic

 

I'll repeat; you CANNOT transform DC, period. You're ***uming because you have a DC supply it's all DC and it's simply not true. Here's some crude waveform drawings but good enough to illustrate this....


Top one is DC. Steady state on both voltage and current for a given circuit. If your waveform doesn't look like this, it isn't DC.

Middle one is AC, one cycle.

Bottom one is what the ignition coil sees. While it's technically 'DC', what matters is the waveform is the same as AC only just 1/2 of it and that's what allows it all to work. The coil sees it as AC and more importantly, the circuit operates under AC laws. The output from the coil will have the same waveform and most certainly isn't DC. The '********s' in the old radios worked exactly the same way, only instead of a set of mechanically-operated points it used a bi-metal set for the same function, sort of a flasher on steroids.

 

Well he did get it fixed.
Basic ignition operation.
When the points are closed a magnetic field builds up in the primary coil.

When the points open that field collapses and the secondary winding creates the spark that goes though the secondary coil wire and to the plug.

The condenser/capacitator acts as a shock absorber for the points to route the primary voltage to ground while absorbing most of that charge so you DO NOT GET a spark across the points. I don't have the info handy but by looking at which side of the points most of the deposit is on you can determine if you have the correct capacity condenser. That I learned in Auto shop cl*** in 1962.

 

... And when the condenser shunts the primary winding voltage to ground, that opens up the ground path for the secondary coil winding.

 

Similar to a VFD, pulsating DC to a high voltage and back to zero, then depending how long the DC voltage is “on” acts as frequency.
I say similar because the DC for a VFD is a square wave that is controlled

 

I think it was here at the HAMB, Bubba's Ignition (Jim Linder) once mentioned a Sears Auto or somebody like that had a 55 gallon drum chock full of old round ignition coils they had ac***ulated over the years. Which they donated to his Ignition schooling course. He had his students test them and said they eventually went through the whole drum and only found a half dozen or so that were actually defective. Something like that.

A few shorted turns in the secondary is hard to detect, coils do go bad, not very often. Both ignition coils and condensers should be tested at normal operating temperature. That means "Hot". Most people don't have the right test equipment. Ohms testing will tell you it "should" work, but that's about it.

 

Sorry Steve, but you're simply wrong. As I posted earlier, in order for the secondary output to be AC the primary input must be AC. And as Squirrel put it, you can have varying amplitudes of DC, which is what you're describing and showing in your drawing. It is NOT, I repeat NOT AC. That is as basic as electricity gets. The current flows 1 direction, and 1 direction only, it is not alternating current, it is direct, 1 direction, period.

 

we might have to look at a real waveform to see what's happening, eh?

Where is zero?

 

That is incorrect, the capacitor does not provide a pathway to ground, it cannot, unless it's leaking, which is a faulty condition. A capacitor is 2 plates separated by an insulator, which is a physical barrier which prevents the flow of electrons, there is no pathway for the current to flow. The capacitor needs to have a connection to ground so there is an electrical attraction, but there is no pathway through it.

 

Now that's interesting Jim, thanks.

 

It is, isn't it.... Care to explain the negative voltage values shown after the spark has ended, and the additional small spike below the 0V line when the points close?

For that matter, I'd love to hear your explanation of how a capacitor works and it's purpose and operation for use in ignition circuits.

 

I have a question. Why will a bad condenser/capacitor, cause the spark to be pink instead of blue? And I do understand pink is a weak spark. And yes I use to charge up condensers and lay them on my bench at the dealership I worked at and wait for my buddies to grab one. I understand how a capacitor works but... did I just answer my own question? lol

 

Care to explain your drawing above? I don't see any negative values in it. Doh! Maybe you should check your at***ude Mr Electrical Guru.

Note the negative values appear AFTER the end of the spark. The negative voltage is part of a flyback current established after the spark, it is an artifact of an electromagnetic transformer circuit with a high rate of discharge and a sudden end of current flow as the spark ends. To equate this with the transformer generating alternating current indicates a complete lack of understanding. What comes from the coil is straight DC, positive voltage rising until it exceeds the requirement to jump the gap. This is basic auto electric theory and I'm surprised at how poorly you understand it.

The capacitor provides storage of electrical charge in the primary circuit, not the secondary circuit. I'm not going to sit here and type basic auto electrical theory to prove something to you in some kind of internet **** measuring contest. If you're struggling to understand this I'm sure you can find a video on Youtube that will show it in basic enough language for you to understand.

The beginning of this discussion between us was when you claimed the capacitor provides a path to ground for the primary circuit. Care to explain how it does that?

Also, care to explain the voltage rating of the capacitor and why it is so much higher than the 12 volt system it operates in? When you answer that, you're on the track to understanding the negative voltage swings in the secondary circuit after the spark ends.

Some guru you turned out to be....

 

BTW, back to your claim that transformers only work on AC, I mentioned to you then the ********s used in old car tube radios to generate high DC voltage. Why you didn't stop then and investigate I don't know, but it would've saved you a lot of egg on your face. Let me help:

There was a growing necessity to create voltages of around 50 to 250V DC from vehicle batteries. Electromechanical segments known as ********s were utilized as a part of a circuit ... to give a throbbing DC which could be changed over to a higher voltage with a transformer, corrected, and separated to make higher-voltage DC. This "********" is basically a transfer utilizing ordinarily shut contacts to supply energy to the hand-off curl, along these lines promptly breaking the ***ociation, just to be reconnected rapidly through the typically shut contacts. It happens so quickly that it is almost like one continuous motion. As it constantly vibrates, and seems like a signal. This same quickly beating contact applies the rising and falling DC voltage to the transformer which can step it up to a higher voltage. This is the intended results that permits the electronic magic to happen.

https://www.vintagecarradio.com/blog/radio-********s/

Read it and weep....