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MG Midget and Sprite Technical - Sat Nav in a frogeye?

The Frog is positive earth. The sat nav runs off negative earth.
How can I use my sat nav?
Thanks from a non electrician!!
Neil (K series)

Take 2 minutes and convert your frogeye to negative earth

swap the battery leads around and flash the dynamo job done. Oh and swap the coil connections around as well.

Here is the link to the MGCC website with the technique required.

http://www.mgcars.org.uk/mgcc/midgetreg/positivetoneg.shtml

If you try to use it in the car as is you will end up blowing something up
Robert (Bob) Midget Turbo

Neil,
Does your satnav not have its own battery? My TomTom runs for about 2 hours without a 12v supply. Charge it up in a modern, then take it with you in the Frog and just turn it on when needed (unless going on a long journey, when you'll need a map. Such as - if you're in the UK - something by, oh, I don't know, maybe the Ordnance Survey...)
Steve Clark

Neil,

I'd have thought that unless the Sat Nav is in some way grounded by a mount all you would need to is make sure the power supplied is the correct polarity and it would be fine.
David Billington

Robert - Thanks for the suggestion.

Steve - The tom tom battery won't last long enough for the distances the Frog travels.

David - The tom tom isn't grounded. If I was to use an independent cigarette lighter plug and connect it to the pos and neg connections of the battery, this should work? I take it that the fact that the Frog battery is itself grounded positive earth, won't make a difference?
Neil (K series)

Neil

On longer runs I take my portable Jump pack in the passenger footwell. (And if out for a week, the charger to give it a boost every third night.) It's one of those (Halfords) ones that has a lighter socket, can start a car or inflate tyres, and has a big emergency torch too.

I have a bracket that mounts the Tom-tom below the dash, out of sight. Seems to still get a signal Ok.

Maps are only good if you have a navigator, or keep stopping...

Andy
Andy Pie-Crust

Hi Andy,
Good idea. That is a real possibility, however would really like to make use of the battery if poss.
Neil (K series)

Negative/Positive earth means sod all really if you're wiring your own kit up!

Just wire a cigarette lighter up the 'wrong' way round and you'll be good to go!
Rich Amos

Neil - If the GPS unit doesn't have any exposed metal parts that are connected to one side or the other of the battery (most, if not all of todays electronics do not have any exposed metal parts connected to the battery), you can install an auxiliary power socket (cigarette lighter socket) that is isolated from the car's chassis, you should be able to wire it to match what the GPS unit needs. The best place to get such a socket is from a marine supply house that carries bits and pieces for private boats. I got sockets that are made of plastic so they are totally isolated from the car's chassis. See the attached picture of the socket package. Cheers - Dave


David DuBois

Keep Positive and buy a Map.... :-)

Mark.
M T Boldry

if you could convince me of a good reason not to change to negative earth then perhaps other possibilities would be worthwhile but I am afraid I can see no benefit whatsoever.

A friend of mine with an early MGB was in the same predicament, I also failed to convince him to change. So we installed a cigarette lighter into his car wired up with negative to the earth (outer part) of the socket. This meant it could not come into contact with anything metal in the car or something would go bang. In the MGB this was accomplished by installing it into the plastic radio blank in the dash. It is difficult to keep the outside of the lighter socket away from touching metal although it is possible such as the MGB. I have also seen some lighter sockets that are insulated from earth but would I trust them? no, however if you insist then be careful and be sure to instal a small fuse into the supply. This will protect the car wiring if you do happen to have a short.
Good luck
Robert (Bob) Midget Turbo

The ONLY reason that I can think of not to convert to Negative Earth is for originality.

Maybe I'm a bit of a sentimentalist, but if I have a car that came out of the factory that is Positive Earth, I like to leave it like that. I'm not saying every one should think the same way or be influenced by my thoughts, it just how I am....

Neil.

Bob's suggestion is probably the easiest and most cost effective.

Mark.
M T Boldry

then i am even more of a sentimentalist

why not use a map!
sat nav was never a part of the possible equipment

I never had the need for a sat nav just carry a good map and i will get anny where
The times i was in a car (as a pasanger)directed by sat nav it told us all kind of stupid things and we had to correct several mistakes of the bloody machines by my topogafical memory!
Onno Könemann

Not only some varied advice, but quite emotive too, Thanks all,
Neil
Neil (K series)

This works for me for 2 years already
Flip


Flip Brühl 948 frog 59

elf portrait with Tom (TOM)

Flip


Flip Brühl 948 frog 59

Flip,
What kind of a mount are you using for that cycle speedometer?
David "artistically challenged" Lieb
David Lieb

I ran my stereo all last season wired direct to the battery (my '63 was still positive earth at the time) All was well unless my iPod slipped and grounded on the ebrake handle---zzzzzzzzzzz. No harm done. I've since converted for the stereo and I plan to fit a Crane Cams XR700 ignition someday (when I fab up a shutter for the dizzy). I say convert it especially if you have a mechanical tach and don't have to rewire an electrical like I did, even that was no big deal.
J Van Dyke

Flip, im shocked, there i was thinking your car was completly original without modern modifications...
A shame realy. :)
Arie de Best

Sounds just a trifle hypocritical caoming from Arie ;-)
David "nothing original" ieb
David Lieb

David you obviously never met Arie
He is always busy with originality!
(and how he can beat it :P)
Onno Könemann

Neil

I have a similar solution to Flip. New wires and fuse direct from the battery and an insulated Halfords lighter socket under the dash. I will take a pic and post pretty easy installation and seems to work well.

Mark
Mark '59 Frog

So Picture 1

The wires direct from the battery. An in-line glass fuse holder may have been better had to insulate the terminals in case they gounded on the body.


Mark '59 Frog

Picture 2

The cable tied 12v socket. If you spent more time you could make this neater! The original heavy plug wobbles free. You could manage to cable tie it vertically. The smaller after market cable is fine. Think Flip's is fixed.


Mark '59 Frog

Picture 3

The nav mounted on it' ssuction pad on the shiny self adeshive disc you can get from Garmin. The vinyl need re fixing on the trim as it was pulling off. The position is good as it does not block the screen and doesn't get in the way of passenger knees.

All I need to do now is learn how to use the sat nav properly!


Mark '59 Frog

Neil

An easy solution is the one I use in my 6volt car. Buy a small (say 150x50x50mm) gell cell from someone like Screwfix and make up a fly lead terminating in a cigarette lighter of a length sufficient to route between the cell and your sat nav lead.

You will then have sufficient capacity for several days use before recharging with a controlled current battery charger e.g. accumate. Don't use an old battery charger without electronic control as there is a risk that the gell cell could explode when charging.
David Southcott

In my everyday 'modern' car, I have satnav, 'phone charger and handsfree charger, so I got a 4-way socket from Poundland for...........£1

It looks like this...

http://img.auctiva.com/imgdata/4/6/4/4/4/2/webimg/56316627_o.jpg

It would be easy to chop off the plug and wire it into your electrics with an in-line fuse.

Gives you a socket for the satnav and anything else you can think of!
Dave O'Neill 2

This thread was discussed between 20/06/2009 and 07/07/2009

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