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Bouncing volt meter needle...


3rdowner
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Hi all.  Yes, another “bouncing needle issue”, however, this one is common, and even expected (referring to my last post regarding a bouncing temperature needle).  I understand the battery-generator-regulator circuit and the related Thevenin and Norton values across any of the lighting circuits, however, my needle jumps like a Jack Russell Terrier in beat with the turn signals.  The needle swings between + ¾ and -1/4 like a windshield wiper.  Q’s:  Is this typical? Is there a way to stabilize or damp the drain in energy?  My first thought is to place a capacitor in the circuit with a dead-short protector.  With that said, what is the collective advice on this subject?   

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19 minutes ago, 3rdowner said:

Hi all.  Yes, another “bouncing needle issue”, however, this one is common, and even expected (referring to my last post regarding a bouncing temperature needle).  I understand the battery-generator-regulator circuit and the related Thevenin and Norton values across any of the lighting circuits, however, my needle jumps like a Jack Russell Terrier in beat with the turn signals.  The needle swings between + ¾ and -1/4 like a windshield wiper.  Q’s:  Is this typical? Is there a way to stabilize or damp the drain in energy?  My first thought is to place a capacitor in the circuit with a dead-short protector.  With that said, what is the collective advice on this subject?   

Whether you think you can, or you think you can't-you're right.-Henry Ford

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Or bad connections or dirty terminal ends at the ammeter (not voltmeter if factory equipment).  Bear in mind that *ammeters* on 6V systems will often register significant current draw based on number and watts of operating bulbs.  And actually, these gauges are more galvanometers than more accurate ammeters.

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Grimy,

 

Great input!  Yes, it is an ammeter (measuring current), reporting out voltage based on the current draw!  I must admit to all reading this post: I haven't a car in my collection newer than 1926.  These modern cars (1931 and later) are new to me.  however, even those with "voltage meters" on the dash are actually displaying current drop across the circuit.  Again, good catch, and I will look into the regulator.  I am curious as to the response/transient time of the gauge, it may be reacting to the historisis (sp?) of the regulator rather than the voltage/current available.

 

Last (almost), and not least, thanks all for pulling me "out of the weeds" when chasing down issues.  I tend to go to the bottom of the fault tree rather than focusing on the top/basics.  I will be researching the best method of assessing a regulator.  However, in actuality, I should just buy a new regulator as my time is worth something (but let's face it, we are all in for the adventure as much as the solution.  We are problem solvers, which doesn't work for us when we are simply suppose to listen and not solve).

 

Peace all, and please read "Adam Smith's Wealth of Nations" (audio book is best, on a commute or daily task-drive), Our country is so-lost in the weeds of "economics-ignorance". And please, do not read into my request any party affiliation. The structure, conduct and accountability Smith talks about are oddly common among all political systems.  It would make a great Netflix series!!! (Rats, I don't have a TV!).

 

Dave

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1 hour ago, 3rdowner said:

Great input!  Yes, it is an ammeter (measuring current), reporting out voltage based on the current draw! 

Dave, the gauge is truly a galvanometer indicating the direction of current -- i.e., in/out the battery.  It indicates, not properly measures, amps (which is current, not volts) only in that sense.  PLEASE disconnect the battery before addressing the contacts on the "ammeter."  I believe in trying the easy stuff first 🙂 .   If you're like me, hang your heels over the front seat back, put a pillow under your head, and put your bifocals on upside down...  🙂

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These old cars have a habit of harbouring bad ground. Check engine to chassis ground for a start. All other grounds are important including the battery. 6 volts are the worst offenders. I am not sure if your car has a voltage stabilizer mounted behind the dash. They do malfunction.  

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I agree with @trini.  An excellent tool for checking grounds, especially on a 6V system, is a good length (6 ft or so) of 10 gauge wire with an alligator clip on each end.  For example, one at a time, ground the gauge base to some part of the body structure, ground the body to the frame.  If the problem disappears from the temporary, add a permanent ground.

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19 minutes ago, trini said:

These old cars have a habit of harbouring bad ground. Check engine to chassis ground for a start. All other grounds are important including the battery. 6 volts are the worst offenders. I am not sure if your car has a voltage stabilizer mounted behind the dash. They do malfunction.  

 

 What  trini said.  Almost assuredly a ground problem.  If I am wrong, lunch is on me next time you are through Wichita Falls.

  Remove the Neg cable from the battery and clean cable and battery post to a HINEY condition.  Same where the Neg cable connects to the engine.

 

  Ben

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Many great suggestions, but Grimy takes-the-cake with the method of hanging upside down!  I laughed because it's true, with the addition of safety goggles (and yes, I wear bifocals, never could adjust to progressives).  I wasn't always so careful in my youth, however, I lost 50% of my vision in my dominate eye (right) do to trauma induced glaucoma, causing open-angle glaucoma (at age 60).  Long story short: I inadvertently stepped on my ceiling-retraceable air hose causing it to spool/retract.  I heard the noise from across the garage and turned just in time to catch the hose with the right eye.

 

Also, TerryB, my apology for missing the "s" in 1940's, no harm, no foul.  To all, I struggle with writing and reading due to dyslexia, the kind of dyslexia resulting in flunking out of high school.  I have overcome the issue, to an extent and am always open to discuss the subject as it is near and dear to both me and my wife (she is also clinically diagnosed with Dyslexia).  As a summary for any that are curious, dyslexics don't sound-out words with phonetics, we memorize words as pictures.  That's why it takes dyslexics so long to master reading and other related subjects.  There are "special" books for dyslexics which are simply common fonts and spacing for quick word recognition.  The good news: dyslexics often development a photographic memory which results in great cerebral spatial perception (geometry, art, working with one's hands, etc.) and learn kinesthetically in the garage with tools!).

 

Must run to the garage now, ya'll gave me way-too-much homework, must get grounded (ok, so dyslexia does not equal humorist).

 

PS: Ben, trini, et. al., if it is a ground issue, lunch is on me if you are ever in Norther Michigan!

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Good luck @3rdowner!  Kudos to you for dealing so well with your eye problems and "lysdexia"....  I had my eyeballs rebuilt early last year (cataract surgery) and couldn't be happier with the results but I know your case is different and far more problematic.

 

Try drugstore or other cheap reading glasses whose prescription covers the whole lens, and the lens as large as possible (i.e., not the small lens where the glasses are perched on the end of your nose) for underdash and other upside down close work.

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The vision information is quite helpful to those like me who do not have that to deal with.  My wife’s vision is very bad, bordering on legally blind without her glasses. I have your normal for a person nearly 70 yrs old eyesight with some cataracts to deal with.  My bigger issue is I’m paralyzed from the waist down, thanks to a T11 complete spinal cord injury in 2012.  My right leg had to be amputated too just below the hip from the same accident.  The score was guy in Jeep not paying attention to traffic 2, guy on motorcycle doing everything correctly (me) 0.  My four wheel entertainment is now charging around the house in my push it yourself wheelchair. 
 

So I hang out here daily offering advice where I can and a little humor at times too.  Always glad to meet new forum members and learn about their projects and problems they are working on wether they be mechanical or human.  Many forum members bring loads of information to the table each day here too. It sure beats watching TV!

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Something that you might look at particularly with an  old car.  The bulb sockets at the Brake/turn signals eventually go bad resulting in a spurious ground.  Your voltage reg and generator might be truly trying to supply the grounded current.  I had to replace the innards   of my  sockets.  You can buy cheap replacement sockets and just use the  little  spring/contacts/wires to replace yours.

 

You might try removing your bulbs one by one to see which one is the culprit.  Good luck

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I always take a look to see how hard it would be to take the front seat out if I have to go under dash.

If I can get the seat out in 15 or twenty minutes it ultimately ends up being worth it.

Another trick is to build a bed of sorts out thru the door. Like a piece of plywood and a couple of jack stands.

Going in with my feet above my head makes me dizzy.

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All,

 

I do have an app that allows my to transmit my iPhone camera to my iPad and it is like having a second set of eyes when working on problem requiring being in two places at the same time.  I use it for diagnosing brake lights, watching the dashboard gauges while working under the car or under the hood.  As for the Lesdixia, my favorite saying is "Dyslexics of the world untie!"

 

PS: on a previous post regarding the "bouncing needle" on my thermoset, opened at 200 F.  I filmed the setup and test and will post on the related chat page.

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