elbanna Posted February 18, 2019 Report Share Posted February 18, 2019 I wish to have a discreet iPhone charging port using a USB cable in my TR3, not sure what polarity is required for this. Your help would be appreciated. elbanna Quote Link to post Share on other sites
RogerH Posted February 18, 2019 Report Share Posted February 18, 2019 Hi Elbanna, welcome to the forum. Your TR3 would normally be positive earth. Not sure if any modern parts would align with that. However if you get a 12V accessory socket https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR1.TRC0.A0.H0.Xin-car+usb+charger+socket.TRS0&_nkw=in-car+usb+charger+socket&_sacat=0 Made with plastic components then the earth polairty shouldn't matter. Then you can plug in a USB charging socket. Roger Quote Link to post Share on other sites
foster461 Posted February 18, 2019 Report Share Posted February 18, 2019 I kept my TR3A as positive ground and used an insulated power outlet mounted as shown in the picture below. There is an inline fuse protecting it and I am aware of the issues of plugging in anything metal that has a grounded case. Our phones and GPS unit are all plastic so I'm not too concerned. Quote Link to post Share on other sites
elbanna Posted February 18, 2019 Author Report Share Posted February 18, 2019 thanks to RogerH and Foster461 good info Quote Link to post Share on other sites
Lebro Posted February 18, 2019 Report Share Posted February 18, 2019 Another option - completely hidden from view Quote Link to post Share on other sites
elbanna Posted February 21, 2019 Author Report Share Posted February 21, 2019 thanks Lebro, definitely discreet that one. Elbanna Quote Link to post Share on other sites
Andrew Smith Posted February 21, 2019 Report Share Posted February 21, 2019 On 2/18/2019 at 5:45 PM, RogerH said: Hi Elbanna, welcome to the forum. Your TR3 would normally be positive earth. Not sure if any modern parts would align with that. However if you get a 12V accessory socket https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR1.TRC0.A0.H0.Xin-car+usb+charger+socket.TRS0&_nkw=in-car+usb+charger+socket&_sacat=0 Made with plastic components then the earth polairty shouldn't matter. Then you can plug in a USB charging socket. Roger Hi Rog, I fitted a modern 12v socket in TuRK (pos earth) and just reversed the wires/polarity - hasn't caught fire since fitted about 10 years ago..... Cheers, Andrew Quote Link to post Share on other sites
boxofbits Posted February 21, 2019 Report Share Posted February 21, 2019 On 2/18/2019 at 10:12 PM, Lebro said: Another option - completely hidden from view Hi Lebro It is very discreet. Where is it exactly ? I can see a plate with a circular hole and what looks like a switch .. Kevin Quote Link to post Share on other sites
Lebro Posted February 21, 2019 Report Share Posted February 21, 2019 The circular hole is the entrance to the cigar lighter socket, you push the plug up into it. The switch is for something else. A bit further towards the battery box is the screen washer pump. Quote Link to post Share on other sites
roger murray-evans Posted February 22, 2019 Report Share Posted February 22, 2019 Elbanna, I fitted an accessory (fag lighter) socket to my (Non TR) 12v Postive earth car, (if that is what you still have) using an existing live feed from the fuse box and earthing to the car body and wondered why I blew the socket fuse everytime I plugged in the SATNAV. After a bit of research I discovered (and I'm sure all the forum electrical experts will already know),if you wish to retain the existing positive earth on your car, but want to use modern electronics such as satnavs etc, you must wire the accessory socket direct to the battery terminals.By this I mean the new socket live wire has to go to the positive or earth terminal on the battery and the socket earth wire must go to the live terminal on the battery.The socket itself must be one of those all plastic encased jobs that cost nowt on Ebay and screwed whereever you like, as long as nothing metal within the socket comes into contact with the car structure.Basically you are wiring the socket into the car but entirely isolating it's electrical circuit from the rest of the car's electrical system. Roger M-E (Awaiting in trepidation an avalanche of rebuttals!) Quote Link to post Share on other sites
Lebro Posted February 22, 2019 Report Share Posted February 22, 2019 That's quite right, personally I can see no reason not to change to -ve earth, which solves these compatibility problems (sat nav, car radios etc) Bob. Quote Link to post Share on other sites
roger murray-evans Posted February 22, 2019 Report Share Posted February 22, 2019 Too easy Bob! RogerM-E Quote Link to post Share on other sites
Richardtr3a Posted February 25, 2019 Report Share Posted February 25, 2019 I have just found this thread. My car is positive earth. I bought a unit with three sockets and one usb . I wired the earth cable from the socket to A3 with an inline fuse and took the power cable from the charger to a nearby earth point. I can use the Sat Nav and charge the phone at the same time. It is mounted on the dashboard mounting strip and I used plastic nut and bolt as a precaution. It works very well. Richard & B. Quote Link to post Share on other sites
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