Masters in electronics EE, specially RF engineering, 30 years.... you?
After 10 years with Boing, I opened service centers for Motorola, GE, and several other electronics companies. taught auto shop for 2 years, General contractors license, and a pilot...

Never shy, but I believe that you are wrong,,,,

explanation: At the same time, current exits the coil's primary winding and begins to charge up the capacitor ("condenser") that lies across the now-open breaker points. This capacitor and the coil’s primary windings form an oscillating LC circuit. This LC circuit produces a damped, oscillating current which bounces energy between the capacitor’s electric field and the ignition coil’s magnetic field. The oscillating current in the coil’s primary, which produces an oscillating magnetic field in the coil, extends the high voltage pulse at the output of the secondary windings. This high voltage thus continues beyond the time of the initial field collapse pulse. The oscillation continues until the circuit’s energy is consumed.... but this is not the op's question,,,

o god... I'm getting sucked in.... this is not where I want to go....I am out of here


OP, the voltage you are measuring is fine, if you turn the distributer slightly where the points are open you will then measure 12v at the coil. if you do all is good with the ballast resistor, it is working properly.

 

[....there's nothing like being a genius in your own mind...]

Folks who really do have knowledge and understanding are always willing to learn. It's the one's who "know it all" that you have to watch out for.

 

Who do you direct this at?
I am fare from knowing everything, and am learning all the time, and have been proven wrong on more than on occasion, which I do not mind...

and on this post forward, I will only post for the op.. not feeling like a fight today/.... been to long of a day already... peace...

 

Not to hijack this thread, but if you install a MSD box, the coil power no longer goes thru the points (or distributor). It just uses them as an on-off signal & they last much longer.

Also, I just ordered the 40th Anniversary 6AL box for my 59 pickup...way cool & worth the extra $75

 

Wow - great discussion - and I appreciate everybody's input. It's great to know that there are so many of you that have a mix of knowledge, experience and passion for this stuff that are willing to share. I've actually got a pretty good understanding of Ohms Law myself, but lacking knowledge of resistor values and load information in the system there wasn't much of way to determine what a reading should be and I certainly dont know what 'normal' is.

I'm sure you've all guessed that my car wasnt running (again) and I was trying to find out if the readings at my coil were normal or not. I had my son-in-law take the voltage reading while I was cranking the car yesterday (couldnt find the alligator clips again) after I posted this thread. I hate to say this, but I wasn't overly confident of the 5v reading that he gave me.

This morning, I put the tender back on the battery and it was fully charged when I got home tonight. I took a reading across the coil with key in run and it was 7v. When I cranked it (yes, I found the alligator clips) it did drop to about 5v.

The carburetor (separate post and saga) was not spewing fuel, so with some nursing the engine started. With the engine idling, the voltage across the coil was fluctuating between 4v and 5v.

I dont know how these values compare to a car that is known to be working properly.

 

that sounds about right for a DVM,.. cool.

 

roy69 glad you fixed your ride.

A resistor wire lowers the current not the voltage. The readings you got with your DVM are OK but for an accurate reading you need a scope.

Formula:
E=I x R
E= voltage
I= current
R= Resistance

That's all I have to say about this.

 

It was just a 'comment', Paul. I didn't direct it at anyone. Did you think it could be referring to you?

 

Would you like to take a shot at answering my quiz question? Here's your chance to shine.

And as Paul said, who are you directing your comment at? If you're going to insult somebody on this thread, at least have the good manners to be specific.

 

No/// im cool... its sometimes hard to read ones true thought through type... we be cool....
we all be cool.... lets talk electronics...k?


ok, in a purely DC circuit a coil, looks as if it is a load, or resistor, then you have the ballast resistor on the other side, when you close the points and close the circuit you now have a voltage divider, so the voltage on the other side of the ballast will be lower... but there are changes in this due to to charging and discharging state of the coil and the changes of resistance in the ballast resistor. but you will see a lower voltage on the other side of the ballast resistor while the car is running.

Here is a page from wikapedia if you want to more closely examine the math... they do a lot better job of explaining it than I.. and I'm lazy

http://en.wikipedia.org/wiki/Voltage_divider

 

The DVM will not respond as fast to rapid voltage changes, thus with a scope you may see voltage spikes and drains. but the DVM will give you an accurate average voltage

well, a resistor does limit current availability, but it does not "reduce" current. Also, when 2 resistors are in a series circuit you have once-again, a voltage divider, please reference above post in wikipedia for the math.

but remember,....Inductive dividers split DC input according to resistive divider rules... p:-)

 

As far as using the DVM - I'm am not concerned so much about the exact reading - but whether it is in the same range that somebody else would get when doing the same test.

You're right on the resistive load - if you've got 1 amp going in, you've got 1 amp coming out (ignoring any I2R losses), but you will have the voltage drop. If you have resistive loads in series, you will have a voltage drop across each but again, the same current flow (again ignoring any heat losses).

 

Oh no, I'm heart broken! Forum trolling 101, 'try and belittle users with a dis wrapped in a backhanded compliment'.

Did your eyes skip over this bit?

What the hell is your point here? The whole reason I used the term 'full battery voltage' was exactly because I knew some pedant would start being specific about battery voltage, which of course will vary, even on the same car, even at different times of the day.

Why are you obsessed with the idea that anyone has stated that the ballast resistor supplies a specific voltage?

As far as I'm aware no one has stated that.

The OP was originally asking for basic diagnostic help with a points ignition system, not an in depth explanation of the operation of a ballast resistor. I know a ballast resistor increases in resistance as current through it increases and attempts to maintain a constant current flow. I also know that ballast resistors are sometimes used to try and compensate for reduced coil output at higher rpm, but he doesn't need to know that to fix his Vette.

If someone asks for help with a misfire I don't launch into detailed explanations of fluid and thermodynamics.
Instead of attempting to show off your knowledge, why not try and write a helpful reply that is useful to the self taught Vette owner, on here looking for help.

I've used hundreds of hand held meters along with diagnostic machines made by Snap-On, Mac Tools, Bear, Sun, Audi, VW, Mercedes, I could go on. Not one has ever shown more than battery voltage on the low tension side of the coil. Unless you get a short across the top of the coil this simply doesn't happen.


Your example is pointless as the HEI system does not load the ignition circuit in the same way as a points system. Also HEI systems use a dynamic dwell system which further stabilizes coil load.

I'm not that familiar with the HEI system but virtually every electronic ignition system I've seen turns the coil feed off if it doesn't get an rpm signal after a few seconds, where as a points system will cook a coil if the ignition is left on with the points in the closed position, a situation that would clearly be exaggerated by increased voltage and current.

I like the fact that you use the term 'oilcan coil', why do you think the windings sit in oil?

A coil is a transformer and the one thing that people know about any transformer is they get hot.

So if I'm correct why did you start your post arguing with me over varying battery voltage?

Bearing in mind you think it's clever to go into ever more detail in an attempt to sound knowledgeable, before I answer your question can you clarify some things for me.

What is the ambient temperature?
What is the ambient moisture level?
What is the ambient air pressure?
What is the compression pressure on this particular example cylinder?
What is the corrosion level on all the terminals in the circuit?
Am I using an analogue or digital meter?
Are the terminals nickel, gold or silver plate?
What's the oxygen content of the cable?
Is the radio turned on?
Is this test real or in my imagination?
Am I really here?


Thanks for that, I can sleep now.........





If you want to show off your knowledge why don't you stick to industry forums and play with the big boys?

A lot of the guys on this forum are self taught and experts in their own chosen fields.

I'm sure they could criticizes many things you do by going into excessive detail but that's a pointless negative exercise.

You know you know what your talking about, I know you know what you're taking about, now why not try and offer some real world help in a form the average user can understand rather than being a pompous pedant.

 

[QUOTE=Golden;1573667783


...........................

You know you know what your talking about, I know you know what you're taking about, now why not try and offer some real world help in a form the average user can understand rather than being a pompous pedant.[/QUOTE]


Mr Golden,

Please believe me when I say I am hurt by several of your comments. Don't smirk. I'm quite serious. I started out my previous reply to you by complimenting you on your knowledge of things automotive, and my belief that you are logically minded, and can be reasoned with. Apparently I'm wrong. I don't say that to be rude or mean. I'm just extremely disappointed that we couldn't have a strictly technical discussion. You've insulted me several times in your post. I'm a big boy, and I can certainly take it, but that still doesn't remove the disappointment of not being able to keep the discussion on a purely technical level. In all honesty, prior to this post I had a high regard for you and your technical understandings, and even your sense of humor. If you recall, I believe I was the only poster to compliment you on your "Enigma inventor" comment in another thread a while back.
You are correct in your statement above, and in all honesty, I do know what I'm talking about regarding this subject. There are millions of vehicles driving in the US and dozens of other countries around the world with my electronics designs under the hood. I take the performance and reliability of my designs very personally. It has never been just a way to get a paycheck to buy beer on the weekends. I was lucky to get into a career I enjoy (and was fairly good at), and also very lucky to have the guy who designed the HEI electronics as my first boss and mentor when I got out of college. There was a wealth of knowledge and experience in the group I worked in, and I benefitted immensely. I make no apologies for that.
You suggested I offer some real world help. Please review my first post (#2). I believe that met your criteria. It was only later, when inaccuracies and blatant factual errors were posted that I responded again. Forgive me, but as an engineer it is not in my comfort zone to sit by idley while untruths are being passed on to new, inexperienced members of our hobby.
I'll admit my ignorance regarding the definition of pedant. I assume it isn't complimentary, given the context of its inclusion.
I think I've spent enough time and energy trying to explain how an ignition system works, so I'll move on to other threads. If anyone wishes to try my quiz question, please drop me a PM.

 

I'm sorry if you feel hurt, my post was to make a point, not hurt your feelings.

Although sometimes you find the more a situation impacts on you, the more you learn from it.



Setting aside the specifics, all I really wanted to get across to you is that when replying to people who are self taught enthusiasts you have 2 options.

Either you write an accurate text book to go with every post or do your best to 'dumb down' (I hope nobody is offended by that) your replies so that they are short, to the point and don't go over peoples heads.

I could spend all day telling people they aren't qualified to choose an uprated sway bar for their car, but short of offering a 3 week online course for all forum members, it's simply not worth it.

If you really feel it's a heinous crime that someone has posted something inaccurate, why not explain why they're wrong, rather than offering them your 'quiz'.

 

With YOUR design? wow.. I had no idea you were so critical to the automotive industry.... Can you please explain to me just EXACTLY what YOU designed all by yourself.... I am sitting an the side of my seat with anticipation!!!

you seem to imply you are an electronics design engineer.... my I ask what your degree is in? and what type of degree, masters? phd? EE? just curious....

p:-)

 

What exactly is being argued?

As with all things physics, there's almost always a right and wrong answer.

 

Hard to day at this point. I'm not an EE but it appears the debate is not over the precise same things in the same context so this could rage forever. My method is to put an oscilloscope on the "thing" being tested and evaluate my pattern against other good and bad wave forms. I have only a superficial understanding of electronics and electricity so the scope is what makes the thing I can't see (the flow of electrons through a conductor) a little less intimidating.

 

Here we go again.

It was my turn in the barrel last week .

 

lol!!!1 guess we all have our turn brother!!

I taught electronics also for several years... about ready to make a video to show how.... but i am probably to lazy..