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Post Info TOPIC: Voltmeter conversion question


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Voltmeter conversion question


Howdy folks!

Over the winter I had Gary the tachman convert one of my factory ammeter gauges over to a voltmeter. He based it on 13.6 charging voltage but I forgot to let him know my alt is putting out 14.4+ being a modern conversion. My gauge is reading hard right now ( wired into 12 volt at stereo) and I am wondering if there is any way I can put something in series to shunt the voltage so it reads more closely to what Gary had spec'd it out to read. The factory ammeter was reading incorrect due to the modern charging system and accesories on the car and even though I know it was a okay having it right under your nose after 30 years always made me wonder if I had a problem:) The meter today on a fresh start new battery is pegging to the right.

Thanks folks!!



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Dave Cosman


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Would it not be simple as adding a resistor of a calculated value in series to the positive side of the gauge?

I'm thinking you might be able to add a small and cheap amazon variable resistor before the gauge. This could allow you to "tune" the gauge needle position at what you feel is the normal running charge.

 

Ask Gary?



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65 Laurentian post, 67 Grande Parisienne 4 door HT. 
 


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Howdy Mark,

Thanks for the reply! I was thinking the same idea but wanted to make sure I was not way out on left field lol. I have sent Gary a message hes a busy fellow so I dont know when I will hear back. Value wise what would you say? He set it for 13.6 and mines I believe 14.5 and above. A variable resistor is an amazing idea thanks! I just need to figure out which one to grab, what would you get if you were in my shoes?

Have an awesome Sunday Mark!!

Dave Cosman



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Dave Cosman


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Glad to help in any way!

If you have any old junk radios around, you could probably harvest a volume control or a trimmer pot out of it. Then experiment and see what they can do.

I have no idea what Ohm value you'd need to drop basically one volt, but I assume if you go to Amazon for a rotary potentiometer, it should be a fairly low total resistance. Too high, and a small movement of the knob might have too big an effect.

 

There are a few electronics experts here that would know exactly what you should look for, I hope they might join in.

 



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65 Laurentian post, 67 Grande Parisienne 4 door HT. 
 


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Thats awesome Mark super cool!!!I actually have many different potentiometers here from guitars I think 250k,500k ect. Its such a great idea though I ran the power from my cd player which is mounted in the glovebox so its easy to get at thankfully those dash bulbs were deadly a few months back what an ordeal! I had her out today and the meter was pinned all the way to the right so will experiment with the different pots I have and report back with the results.

If your ever out in Alvinston I owe you a few beers for sure!

Dave Cosman

 



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