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Old 12-30-2015, 09:59 AM   #1
flatheadfan
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Default This doesn't make electrical sense.

If you have your entire car original (6 volt positive ground) and wish to run an accessory such as a modern radio (12v, negative ground), you need a converter. I have used these in several cars over the years without ever experiencing a failure. This is where the puzzle comes in.

Since the radio is grounded to the cars' chassis it would seem that you would have a negative ground and a positive ground conflicting with each other which would lead to all types of gruesome possibilities. But, it doesn't happen. I need some help on this to understand it!

Thanks

Tom
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Old 12-30-2015, 10:08 AM   #2
JSeery
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Default Re: This doesn't make electrical sense.

I would think the converter would have to have it's own ground. Are you saying there is just one wire from the converter to the radio? Don't see how that would work, it should require a return path.
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Old 12-30-2015, 10:44 AM   #3
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Default Re: This doesn't make electrical sense.

I have the same setup for my lighter socket to charge my phone.

Wires or frame and any metal in the car is neither positive nor negative in and of itself. It's just a conductor used to complete a circuit and current path from a source that creates it. The inverter is such an independent power source. It sends a positive current to the radio and uses whatever the radio is grounded on to complete the circuit back to itself through its own ground. It is like a little negative ground battery operating independently of the battery. It doesn't matter that the battery is using a ground source to complete its positive ground circuit back to itself.
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Last edited by Old Henry; 12-30-2015 at 11:41 AM.
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Old 12-30-2015, 11:15 AM   #4
Tim Brown
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Default Re: This doesn't make electrical sense.

Is there a converter that bumps the stock 6 volts up to 12 volt to power the radio? Where does the other 6 volts come from?
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Old 12-30-2015, 11:28 AM   #5
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Default Re: This doesn't make electrical sense.

Quote:
Originally Posted by Tim Brown View Post
Is there a converter that bumps the stock 6 volts up to 12 volt to power the radio? Where does the other 6 volts come from?
Yes. That's what the 12 volt inverters do. They use the 6 volts from the car battery to not only create 12 volts but make the polarity negative ground.

Here's the one to use with positive ground system:



Here's the one for negative ground:



Both available here: http://www.classiccarstereos.com/cat...onverters.html
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Last edited by Old Henry; 12-30-2015 at 02:04 PM.
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Old 12-30-2015, 11:50 AM   #6
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Default Re: This doesn't make electrical sense.

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Does this indicate that I can use a 12 volt GPS in my 6 volt pos. ground 34?


QUOTE=Old Henry;1214700]Yes. That's what the 12 volt converters do. They use the 6 volts from the car battery to not only create 12 volts but make the polarity negative ground.

Here's the one to use with positive ground system:



Here's the one for negative ground:



Both available here: http://www.classiccarstereos.com/cat...onverters.html[/QUOTE]
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Old 12-30-2015, 12:16 PM   #7
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Default Re: This doesn't make electrical sense.

Quote:
Originally Posted by Tim Brown View Post
Where does the other 6 volts come from?
Think about your ignition coil, or induction coil.......how does it turn 6v into 15,000 or 20,000v at the spark plug? DD
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Old 12-30-2015, 12:25 PM   #8
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Default Re: This doesn't make electrical sense.

I think you answered your own question when you ask it. Ground is ground, whether it is positive or negative. You always have a power side and a ground side.
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Old 12-30-2015, 01:29 PM   #9
Kurt in NJ
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Default Re: This doesn't make electrical sense.

I used a converter in my positive ground MG for many years. The only problem was when one of the speakers went bad it grounded and there was smoke from that speaker --- the radio and converter were ok
I did mount the converter in the spare tire compartment to hide the noise
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Old 12-30-2015, 01:34 PM   #10
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Default Re: This doesn't make electrical sense.

Evidently, not everybody is familiar with these converters. This is what I am using:

http://www.ebay.com/itm/6-to-12-Volt...JWKXSz&vxp=mtr

Tom
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Old 12-30-2015, 02:05 PM   #11
Old Henry
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Default Re: This doesn't make electrical sense.

Quote:
Originally Posted by 34fordy View Post
Does this indicate that I can use a 12 volt GPS in my 6 volt pos. ground 34?
Yes, anything up to 10 amps as shown on the inverter.
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Old 12-30-2015, 04:46 PM   #12
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Default Re: This doesn't make electrical sense.

Basically, if you double the voltage you halve the amperage.
in other words 6 volts at 10 amp current draw, gives you a 5 amp at 12 volt capability. The old style was just like a transformer. the "in" circuit is separate from the "out" circuit and the ratio between "in" and "out" depends on the number of windings in each. Just like your ignition coil.

In this case, twice as many windings on the "out" as the "in" gives you double the voltage. How ever nothing is free, so as said, the amperage able to be delivered is halved. I hope that helps.
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