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| | | | Joined: Feb 2013 Posts: 250 'Bolter | | 'Bolter Joined: Feb 2013 Posts: 250 | OK, just when I think I'm getting a handle on all things electrical I run head first into something that doesn't work even though I think it should. I have 3 extra ammeter gauges in my pile of old parts and I'd like to use one of them in Speedy, my '48 GMC, where I'm replacing the modern gauge cluster with an original style one. I've managed to Frankenstein a cluster together, refacing the gauges as I go, but before I reface and install the ammeter I want to make sure that it works . I thought I would enlist the help of my '48 Chevy truck, Pokey, by carefully attaching jumper wires from his working ammeter to the terminals on the ammeters I want to test. I do,but nothing happens on the gauge I'm try to test though the gauge in the dash works fine. Is this a method that should work to test the gauge or is it completely stupid? Wouldn't be the first time for me! Thanks, Jim | | | | | Joined: Feb 2004 Posts: 29,742 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,742 | Easy- - - -just connect two fairly large wires, #12 of bigger to the ammeter and use it to power something like a headlight, a heater motor, or some other device that will draw enough current to see the needle deflect. Reversing the direction of flow through the wires will make the needle deflect toward the + or - direction. When current flow stops the needle should return to center. You are aware that dash mounted ammeters are about as accurate and trustworthy as political promises, aren't you?
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Dec 2015 Posts: 52 Wrench Fetcher | | Wrench Fetcher Joined: Dec 2015 Posts: 52 | spot on jerry, as all ways . i run all my power threw my amp meter , so i can see all draw threw the hole system | | | | | Joined: Feb 2013 Posts: 250 'Bolter | | 'Bolter Joined: Feb 2013 Posts: 250 | Jerry, I don't care about the numbers on the ammeter, just charge or discharge is all I'd like. I can test the gauge the way you mention, I'm just wondering why my jumper wire method didn't work. I guess the redundant gauge doesn't get any current flowing through it. And I do apply a heavy discount to political promises.
Jim | | | | | Joined: Feb 2004 Posts: 29,742 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,742 | You were running a parallel circuit- - - - -the original ammeter had a better connection, probably one with lower resistance, so virtually all the current followed that path. Basic Ohm's Law! You would have to put both ammeters in series with each other for your test method to work.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Feb 2013 Posts: 250 'Bolter | | 'Bolter Joined: Feb 2013 Posts: 250 | | | |
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