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I have been wondering how I could power a gps or charge a cell phone when in my Packard. As you know, as do all cars prior to 1955, it has the wrong polarity (positive ground) and wrong voltage (6v).

I did some searching on the web, and found no practical solution available. Years ago (not long after cars switched from 6v to 12v in 1955) some 6v to 12v converters were made, but they were very inefficient, large clunky things. I found some of the old ones still available on ebay. Building a 6v to 12v converter today is easier, but upconverting voltage is inherently inefficient and takes a bit of circuitry. What was needed here is a very steady 5v (actually 4.75v to 5.25v) supply for a usb device charging - virtually all modern devices charge from usb - iphone, blackberry, gps systems, etc... The voltage supplied at the cigarette lighter (or cigar lighter as it was called in 1954) can vary quite a bit. Simply using a voltage divider circuit with a few resistors is tempting, but since the cars voltage isn't constant, neither would be the voltage that the circuit produced. I would hate to ruin my iphone or gps by supplying it with incorrect charging voltage.

So I did a little digging, built a circuit based on a low dropout voltage regulator chip and gave it a try. Success! Works like a charm. Constant 5v dc output from the cigarette lighter in my old car.

Here are some pics. Maybe I'll build a neater version now.

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Very nice. Be nice to put it inside a lighter plug if there is room and then run the USB cable out.parts-express.com/pe/showdetl.cfm?PartNumber=265-562

Or just drive a 1956 Packard. 12V negative ground. I use my GPS in my car all the time.

I bought one of those 6 V pos grnd to 12V neg grnd converters from Ebay ($60). I've had it in my car (38 cpe) for 3 years now - works great. I can run my AM/FM radio and I put in a 12V acc. plug for running the GPS and charging the cell phone and the like. So far no problems.

running other 12v accessories is an advantage. If someone were to build a 6v pos gnd to 12v neg gnd converter using modern technology that would be nice too.

Wouldn't it be easier and ultimately safer to just use an auxillary 12v motorcycle battery mounted somewhere???? The e-devices are very insignificant current draw????? So a fully charged m/c battery would last days before a recharge is needed??? OR is that just another case of "endless guessing" for a "simple solution to a complex problem"??? Gufwah ha ha ha ha ha .

The reason i recommend the aux battery is in view of so-called 'surge protection' devices for various e-devices. It is my understanding that their capacity to protect diminishes with each 'hit' it takes and therefore are recomended for replacement every so often.

I'm definately no expert on chips, diodes, transistors nor the like. But if we go with what know then we don;t have to worry about some transistor going bad and ruining our expensive cell phones and the like.

Looks like this could work - but not a lot of power.

cgi.ebay.com/Classic-car-6V-12V-voltage- ... &hash=item5197a770e0#ht_1268wt_1398

This could do it too, but is an install - I see that the minimum input voltage is 6.3 volts which is cutting it close.


cgi.ebay.com/6-12-VOLT-CONVERTER-RUN-12V ... 3&hash=item3cbae8c43f#ht_931wt_1398

The reason I made mine is that I am only looking to charge a phone or use a GPS. It cost me about $8 in parts. - and it seems odd to me to convert 6 to 12 so that you can convert it back down to 5v. If you have a device that needs 12v (like a radio) that's another story - but they usually need a bit of power, like the second link above.

Maybe supply us with some instructions/part numbers for chips on how to build the one u made in post #1 above.

54Clippers converter mite be of interest to 55 Packard owners. 55's were 12v but POS ground.

Quote:

I easily changed the polarity of my '55 Clipper from positive to negative ground. I reversed the leads to the coil, changed the battery around, and re-polarized the generator. No problems, no drama, just enhanced convenience. This will work if there are no solid state components in the system, like the radio. Otherwise enjoy the world of negative ground.

(o{}o)