TR2/3/3A Phone charger & Radio can I put these in my car???

[Momikey]

Hello,
Is it possible to put a phone charger (USB) or a cigarette liter to charge my phone with in my tr3a with the positive earth ground or do I have to change it over to a Negative ground for that to work?
I know they have positive ground radios I am looking at some hidden Bluetooth radios to just play music off of my phone but It would be nice to be able to charge my phone in the car for the music and the GPS.

 

[TR4nut]

You can but I recommend getting the car switched to negative ground. A friend of mine ruined a gps because it shorted out in a positive ground car simply by having the case touch a metal part in the car. Much better in my opinion to just convert over.

 

[Andrew Mace]

I agree. Changing polarity is simple (and completely reversible -- again -- in the future)! Likely you wouldn't be able to completely isolate even ONE mount for radio, etc., in the time it takes to change the polarity!

 

[TR3driver]

Ditto. Can be done, but best to convert.

Third option is a "polarity converter", which is basically a power supply that runs on -12v and produces +12v. But they are expensive and won't work with some devices. Still better to go to negative ground, IMO.

 

[John_Progess]

I have a cigarette lighter is my positive ground cars. I install the lighter is a piece of PVC pipe and attach it to the car. Make sure the car frame does not touch the body of the lighter and make the correct connections to the lighter and no problems.

John

 

[Momikey]

Thanks all great ideas. I think I will convert over.

 

[TR3driver]

Make sure the car frame does not touch the body of the lighter and make the correct connections to the lighter and no problems.

The problem with that approach is that sometimes you get unexpected, 'sneak' paths to ground; which of course are a direct short when using negative ground devices in a positive ground car.

Many years ago, a buddy of mine put a negative ground CB radio in his positive ground MGA. What he didn't realize was that the antenna mount was grounded through the coaxial cable to the radio body. It all worked fine at first, he mounted the antenna to the back bumper and apparently the bumper mounts were too rusty to make electrical contact to the frame.

We were rolling down I-70, couple hundred miles from home, when vibration finally cleared out the rust and the bumper made contact. Unfortunately, he had neglected to use a fuse, and the short pretty well burned up the entire wiring harness! But after a few moments of pure terror, we got the fire out and were able to cobble together enough wiring to finish our trip.

Sure would have been a lot easier to switch to negative ground, though!

 

[Got_All_4]

Your other possibility is to use a voltage inverter. I used this Archer unit for 20 years in my positive ground TR3 to run the radio. I took it out years ago as I "was" going to go to a alternator system but changed my mind. I had already purchased the Pertronix for the distributer for negative ground thinking I was going to convert. So I did have to go to negative ground to use the Petronix. Now that I'm about done with the 2nd restoration I'll just hook up the radio as normal and was planning to list this on EBay.