WTD 6 VDC Pos Ground to 12 VDC Negative ground Convertor or Schem.

[Carl WA1KPD]

Hi
I need to get 12 VDC neg ground out of my 6 Volt pos ground 51 GMC. Would like at least an amp but really like about 5...Anybody have a circuit, or something to sell/trade?
Thanks
Carl
/KPD

[WD5JKO]

Carl, maybe this will do:

http://www.ebay.com/itm/Ford-Model-A-Flathead-V8-Converter-6-8-volt-Positive-Ground-to-12-Volt-Neg-/280846440566?pt=Car_Audio_Video&hash=item4163c09876&vxp=mtr#ht_1232wt_948

Jim
WD5JKO

[KM1H]

Why not convert to 6V negative ground first? If its a stock truck the change is minimal.

Ground the other battery terminal
Repolarize the generator
Reverse ampmeter leads
Reverse ignition coil leads

The complete job is probably 30 minutes or less and Ive done it to many flatty Fords.

Then a power converter becomes simple.

OTOH I could run a 12V AM/FM SS radio almost a full season on one charge of a junkyard 12V battery in the trunk. No hash either.

Carl

[Carl WA1KPD]

Jim,

I am considering that. I had seen it before, just wanted to see how hard it was to build one. There is also a used RS convertor for sale there too.

Carl,
Agree it would be easy but I like to keep it stock

Carl

[KM1H]

It would be more stock than adding a SS converter, a matter of turning the battery around.
And a lot safer too if someone tried to jumper you and bumpers touched......

[WD5JKO]

My brother had an old 6v pos ground Chris Craft inboard system in his boat. The details are fuzzy, but when he tried to make it negative ground his three brush generator suddenly went up in smoke.

Jim
WD5JKO

[Carl WA1KPD]

It would be more stock than adding a SS converter, a matter of turning the battery around.
And a lot safer too if someone tried to jumper you and bumpers touched......

But unplugging the convertor from the 6V positive  cigarette lighter and removing the convertor box from the seat along with the cell phone and GPS will restore it to stock in about 30 seconds
Im looking for light duty

[KM1H]

Whatever spins your crank

[WD5JKO]

Interesting read about 6V + GND to 12V - GND converson on a 1955 Ford:

http://reviews.ebay.com/6-to-12-Volt-Conversion-1955-Ford?ugid=10000000001571127

Going to 12V brings in many more issues to contend with.

[The Slab Bacon]

My brother had an old 6v pos ground Chris Craft inboard system in his boat. The details are fuzzy, but when he tried to make it negative ground his three brush generator suddenly went up in smoke.

Jim
WD5JKO

3-brush "self exciting" generators are a little bit of a different animal. they rely very heavily on the residual magnetism in the field iron. And........they just use a cutout only, not a full voltage regulator. You adjust the 3rd brush to limit the total charging voltage. If you wish to change the polarity of the outpoot, it is best to disconnect it from the 3rd brush, hit it with a little AC to demagnetize it, then hit it with a little DC to remagnetize it the opposite polarity.

Been many years since I have done one, but I did do a bunch of them years ago.

the standard "more modern" 2-brush type are much simpler, you just pop the cover off of the regulator, hold the cutout relay in for a few seconds before starting the engine, then do it again after it is running and let it run for a while and you're good to go.

[KM1H]

Its even simpler than that with the later 2 brush gennies. Simply do a momentary jump between Bat and Gen terminals on the regulator. Often needed when a vehicle is long stored, battery disconnected or genny replaced.

I still have a jumper made specifically for that.

Switching to negative ground is perfectly acceptable to even the various car clubs since it is a safety and convenience issue.

[The Slab Bacon]

Its even simpler than that with the later 2 brush gennies. Simply do a momentary jump between Bat and Gen terminals on the regulator. Often needed when a vehicle is long stored, battery disconnected or genny replaced.

the standard "more modern" 2-brush type are much simpler, you just pop the cover off of the regulator, hold the cutout relay in for a few seconds before starting the engine, then do it again after it is running and let it run for a while and you're good to go.

  

[K5WLF]

Years ago, I changed my '56 Jeep CJ-5 over to 12 VDC negative ground. I used a GM 10-SI alternator, left the 6 volt starter and all was well. Drove it that way for a dozen years or so before I sold it. It was part of a frame-up resto, so I did rewire it since the old cloth insulation on the factory harness was getting brittle and cracking. Only thing I'd do differently if I had it to do all over again, is keep the Jeep rather than selling it.

[The Slab Bacon]

My standby generator at home (a 1948 U.S.Power and light 5 Kw) has a 6v Autolite starter on it. (3-bolt Ford style with the Bendix drive hanging out on the shaft). I have been cranking that thing with 12v for more than 30 years now.

[KM1H]

Having to take the regulator cover off is a waste of time

My 54 F-350 has been using the stock 6V starter since the PO converted to 12V in the 70's.

[W1TAV]

Just one point, if you stick with the 6 Volt system and re-polarizes the Generator you DO NOT need to change the +/- on the coil, however do need to add a resistor.   While a 12 Volt upgrade may seem appealing, unless you have the starter rebuilt using a 12 volt field coils your are likely heading for some trouble with the Bendix drive.   Yes running a 6 volt starter off a 12 volt system will work, however the torque and issue with the Bendix and ring gear can be a problem.  Back in  the 70's I worked few of these conversions in DIVCO's ( the old stand up to drive milk trucks) and today still play with model T's and have seen the error in simply dropping  in a 12 Volt Battery and changing out the bulbs.. (Although a Model T is a Negative Ground to begin with) - Steve

[Carl WA1KPD]

OK- I hear all of you.

I don't want to change the voltage or polarity. All I asked was for a schematic for a 6 volt pos ground to 12 volt neg. ground convertor. I want to be able to run my GPS and charge my cell from time to time. If I can find one with enough Moxie to run a small 2 m rig, fine. If not, I'll survive.

If no one has plans, I'll go with one of the ones on eBay

Carl
/KPD

[WD5JKO]

Carl,

  I did look around. Looking at switch mode typologies, the inverting "buck-boost" will do the trick. You can Google that. I did find some circuits but they were all positive input to negative output. If you want regulation, low ripple, high efficiency, then doing a ground up DIY design is a big job; except for the other Carl who could do it blindfolded in 30 minutes or less. 

Jim
WD5JKO

[Carl WA1KPD]

Jim,

Appreciate it. I did try Google, but did not see that site. Agree, its amazing the way the thread evolved. If I wanted to change the voltage, polarity or add in another battery I would have done so. I thought the questions was pretty basic

Best 73
Car;l
/KPD

[WA2TTP Steve]

I had an 64 VW bug with a 6 volt neg ground system. I HB my own 6 to 12 volt DC converter that provided about 3 amps at 12 volts. I used this to power a UHF 2 way radio and the car BC radio/tape player. I had installed a 12 volt car battery under the rear seat to provide the current needed to power the 2 way radio on transmit, 20 amps or so. It worked great with no ripple problems. The converted was tied to the battery thru a diode and the loads were all connected directly to the 12 battery thru a DPST relay that also turned on the converter with the ignition switch.

These converters are available on the web.
http://www.6to12volt.com/
6 volt input pos ground no problem.

Good luck.

Steve

[KM1H]

Just one point, if you stick with the 6 Volt system and re-polarizes the Generator you DO NOT need to change the +/- on the coil,

Not true. Not swapping the wires sometimes works but the HV is reduced as its a buck/boost winding. Having mostly worked with flathead V-8 and Y Block Fords I guarantee they need all the voltage they can get. Even more so with the V-8 and V-12 flathead Lincolns.

Slightly OT but the Dodge electronic ignition coils at least to the mid 80's are 6V and use an external resistor. They make excellent high output coils for the oldies.

Carl

[KB2WIG]

Lobster Thermidor a Crevette with a mornay sauce served in a Provencale manner with shallots and aubergines garnished with truffle pate, brandy and with a fried egg on top and spam.


klc

[The Slab Bacon]

Not true. Not swapping the wires sometimes works but the HV is reduced as its a buck/boost winding. Having mostly worked with flathead V-8 and Y Block Fords I guarantee they need all the voltage they can get. Even more so with the V-8 and V-12 flathead Lincolns.
Carl

I got a bridge for sale if ur interested       Get real, Carl 6 0r 12v difference over 20,000v is like pissing in the ocean. It will make absolutely no appreciable difference whatsoever.
You may well have me by a few years, but I have probably worked on more of that old stuff than you. I still even have ingots of babbit for pouring babbit bearings. I was the last guy in baltimore that poured babbit bearings. 

[KM1H]

I got a bridge for sale if ur interested       Get real, Carl 6 0r 12v difference over 20,000v is like pissing in the ocean. It will make absolutely no appreciable difference whatsoever.

Its not as simple as that and I'll refer you to any competent vintage car forum to complete your education...this is not the place.

You may well have me by a few years, but I have probably worked on more of that old stuff than you.

I seriously doubt that as Ive been at it since 1955 and as more than a hobby at times. I just sold the R&C shop 2 years ago to my manager after a 30+ year run starting as a part time thing and ending up full time with 3 employees. My speciality was hammer welding, lead work, and engine building and I still get called to help out.

I still even have ingots of babbit for pouring babbit bearings. I was the last guy in baltimore that poured babbit bearings.

 

I still help a local who does Model A engines along with a few oddballs a year. Pouring is the easy part.

[The Slab Bacon]

Carl,
       I have done all of the above. I have done more than my share of hammer welding. I learned way back before the advent of small portable wire-fed machines.
I have hand pounded body panels out of flat sheetmetal. It used to amaze my wife to watch me do it. Leadwork is easy once you learn to tin the metal so it will stick. I find it easer than bondo because you can keep heating and reshaping it with a paddle til you get the shape you are looking for. I can and have run EVERY machine in an automotive machine shop. From a line boring rig to a Sunnen CK-10. I even mastered custom paint work (including metalflake) when it was done in lacquer. Long before the days of the basecoat / clearcoat finishes. Over the years I have had my hands in everything from lawnmower engines to a top alcohol funny car.
Anything automotive was what I lived for but................... I did something very stupid..... I took what I did for enjoyment and turned it into my living. I finally got so burned out with it, I walked away and never looked back. "Back in the old days" it was pretty tough to make any real money at it, and many times you were lucky just to get a cheeseburger out of the deal.

If you want to discuss cars and older automotive stuff, you are right in my comfort zone. Feel free to bring it on. We can do it by email and not snarl up this forum.