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12 volt down to 6 volt

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Tom/Idaho

01-25-2002 14:36:18




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I have removed the ballast resister and wish to find the right resister to drop the 12 volts down to what the 6 volt coil will handle. Local parts store says I need a 3 ohm resister. They say I will have to wire 2 in series to get the needed drop in voltage. Does that sound right? For some reason I am unable to access the past pages to reread the recent post from Dell that adressed this issue.
Thanks for any help, Tom/Idaho

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DavidO

01-26-2002 08:39:54




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 Re: 12 volt down to 6 volt in reply to Tom/Idaho, 01-25-2002 14:36:18  
The diode "dropped the voltage" on the AC line because it only passed one side of the AC voltage. Pulsating DC. That will not work with DC voltage. If it is a silicone diode (common), it will block all voltage wired in one direction and drop about .7V wired in the other direction. You could wire nine diodes in series and drop about 6V, but why would you want to do that when one resistor will do. The resistor also tends to regulate the current by going up in resistance as the current increases. This causes (a positive coefficient) resistor to increase in resistance and reduce the current. Sort of self regulating.
Forget the diode. Use a resistor.

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Dell (WA)

01-25-2002 17:05:26




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 Re: 12 volt down to 6 volt in reply to Tom/Idaho, 01-25-2002 14:36:18  
Tom..... ..you can do a search on 6-12 volt conversions for frontmount ignition coils and the information is alway been repeated the same way. If you wish to use your OEM 6 volt frontmount ignition coil when converting to 12 volts. You need to use BOTH the infamous "ballast resistor" on the back of the dash panel AND you need a 12-6 volt dropping resistor. Wire them in series just like flashlight batterys.

A good autoparts store will know what a 12-6 volt converting resistor is. There are several out there and I don't favor one over the other. BUT yes, the typical 12-6 volt dropping resistor will be about 3 ohms and eazy to mount somewhere it won't melt the plastic wire insulation..... ...Dell

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kraig WY

01-25-2002 15:07:40




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 Re: 12 volt down to 6 volt in reply to Tom/Idaho, 01-25-2002 14:36:18  
I wanted to reduce my welder to weld ligher material. I have a 295 amp AC stick welder. I put a diod in line with the welding cables with a heat sink. I ended up cutting my amps in half but it switched to DC. I think if you go to Radio Shop and tell them what you are trying to do they could give you the right diod to reduce you from 12 volt to 6 volt. This is just a guess on my part but someone in a electrical shop (Radio Shack) will steer you in the right direction.

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Don, Luling LA

01-25-2002 17:13:11




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 Re: Re: 12 volt down to 6 volt in reply to kraig WY, 01-25-2002 15:07:40  
A diode works like an electrical check valve when used with AC. The reason your amperage dropped in half is because you now have deleted the part of the AC cycle that the diode is blocking. If I remember right a diode will only have a consistent voltage drop of 1.4 volts. I can't imagine that your welder would work very well now since I would also think you would have reduced your AC frequency of 60 Hz to a pulsulating DC at a frequency of 30 Hz. I would imagine that in doing this your rod tends to do a bunch of sticking when trying to weld. You must have one heck of a doide to handle that kind of current.

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wrong . . . Dell (WA)

01-25-2002 16:51:40




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 Re: Re: 12 volt down to 6 volt in reply to kraig WY, 01-25-2002 15:07:40  
Kraig..... ..sorry ol'feller, diodes on battery DC don't reduce voltage like it kinda does on AC. Diodes will eather block or pass electrical current according to its polarity. This is advanced electrical theory 101 and is best taught with a blackboard instead of e-mail..... ...respectfully, Dell



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kraig WY

01-25-2002 18:18:09




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 Re: Re: Re: 12 volt down to 6 volt in reply to wrong . . . Dell (WA), 01-25-2002 16:51:40  
Like I said I didn't know if it would work on the small electrical stuff. I did it to reduce the amps and switch to DC. I also switched to DC rod, 1/16. And it seemed to work. I did have to put in a large heat sink, about 1 sq. ft. of copper plate. I really couldn't say why or how it works. The diod is about 8 in. long. Some guy gave it to me several years ago when I was trying this project.

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