barber007 Posted October 17, 2009 Report Share Posted October 17, 2009 (edited) Hi - can anyone out there in Tr land help? My Husband has wired an off the shelf car cigarette lighter to our Tr2. He has wired it directly off the battery. It has a 5amp fuse in the lighter. Every car charger I own and ipod charger has blown the fuses in the chargers themselves. We have a cd player whose car charger is not fused and it runs the cd okay. So clearly it is something to do with the modern chargers. Can anyone help out please. Edited October 17, 2009 by barber007 Quote Link to post Share on other sites
RogerH Posted October 17, 2009 Report Share Posted October 17, 2009 Husbands - what would you do with them !! The TR2 is positive earth and any modern appliance will be wired for negative earth. Have you got the polarity correct. Some appliances may have a bridge diode across the input thus sorting out any input problems - but not all!! Roger Quote Link to post Share on other sites
Menno van Rij Posted October 17, 2009 Report Share Posted October 17, 2009 If you have a look on this picture, don't look at the doorpanel , just look a little further: you can see a little, shiny panel with the cig. lighter mounted. This little panel is attached to the part of the pedal box that points backwards under the dashboard. I'm sure I have more pics, but not on Photobucket like this one; if you need additional pics, please send me a PM! Menno Quote Link to post Share on other sites
JJC Posted October 17, 2009 Report Share Posted October 17, 2009 Husbands - what would you do with them !! The TR2 is positive earth and any modern appliance will be wired for negative earth. Have you got the polarity correct. Some appliances may have a bridge diode across the input thus sorting out any input problems - but not all!! Roger I've fitted one of these to the TR6 and tried to get the polarity right by measuring the polarity in one of our family cars. Does anyone (hopefully an electronics expert) know for sure whether the central pin in the accessory plug is positive or negative? For safety I connected mine so it switches off with the ignition. JJC Quote Link to post Share on other sites
tthomson Posted October 17, 2009 Report Share Posted October 17, 2009 Hi, The early TRs were Positive ground whereas later TRs and modern vehicles are Negative ground. The centre connector of the power socket (cigarette lighter socket), should be positive and the outer body negative for it to suit modern electrical devices. The problem with this is that, typically, the outer body of the socket is connected to ground via the fixing method. so you end up with a short circuit in the car if you do not take precautions to isolate the socket from the car's metalwork. (Plastic bracket maybe?). The problem you have experienced with modern chargers is because the polarity of the plug (positive central connector), is the reverse of the socket, (negative central connector), causing the charger to be effectively short circuited. This is always going to blow a fuse when you connect such a charger. It is an easier task to swap the polarity of the socket than it is to change everything else. It looks to me that the CD player has an inbuilt bridge rectifier circuit which means it doesn't matter that it is connected to a reversed supply. I hope this helps TT Hi - can anyone out there in Tr land help? My Husband has wired an off the shelf car cigarette lighter to our Tr2. He has wired it directly off the battery. It has a 5amp fuse in the lighter. Every car charger I own and ipod charger has blown the fuses in the chargers themselves. We have a cd player whose car charger is not fused and it runs the cd okay. So clearly it is something to do with the modern chargers. Can anyone help out please. Quote Link to post Share on other sites
JJC Posted October 18, 2009 Report Share Posted October 18, 2009 Thanks - I'll go back and check the polarity in the TT first then the TR. If they both say positive then I'll risk plugging in the TomTom which I haven't had the courage to do yet. The sockets I used had both central connector and outer ring wire connected since the whole socket, and fixing, is plastic. Has a little light in it too. Incidentally, I suspect modern cars have a stabilized positive rail, possibly surge protected as well. Will the Tom Tom be at risk without that? JJC Quote Link to post Share on other sites
tthomson Posted October 18, 2009 Report Share Posted October 18, 2009 Hi JJC The chances are the TomTom has a regulating circuit in it. Modern electronics run on 3.3 Volts, or earlier systems on 5 Volts, so the supply from a car socket will be regulated down to the appropriate voltage inside the TomTom TT Thanks - I'll go back and check the polarity in the TT first then the TR. If they both say positive then I'll risk plugging in the TomTom which I haven't had the courage to do yet. The sockets I used had both central connector and outer ring wire connected since the whole socket, and fixing, is plastic. Has a little light in it too. Incidentally, I suspect modern cars have a stabilized positive rail, possibly surge protected as well. Will the Tom Tom be at risk without that? JJC Quote Link to post Share on other sites
barber007 Posted October 18, 2009 Author Report Share Posted October 18, 2009 Thanks to you all for your helpful comments. My husband has now changed the polarity of the car from positive earth to negative earth and the cigarette lighter socket issue is now resolved. I will await the next issue that will no doubt crop up and look forward to more helpful advice from my fellow Tr pals. Quote Link to post Share on other sites
Andrew Smith Posted October 18, 2009 Report Share Posted October 18, 2009 ..........It is an easier task to swap the polarity of the socket than it is to change everything else. Question, not a statement: I guess you would get away with just cutting the wires on the Tom Tom lead and reconnecting them the other way round to reverse the polarity? Cheers Andrew Quote Link to post Share on other sites
RogerH Posted October 18, 2009 Report Share Posted October 18, 2009 When you say he has changed the polarity of the car has he sorted the dynamo etc not just swapped the battery terminals over!! I know it's a silly question but!!!!! Roger Quote Link to post Share on other sites
johnny250 Posted October 18, 2009 Report Share Posted October 18, 2009 Question, not a statement: I guess you would get away with just cutting the wires on the Tom Tom lead and reconnecting them the other way round to reverse the polarity? Cheers Andrew Andrew, If it's a similar model to my TomTom, what looks like a regular cigar lighter plug actually contains a switched mode power supply! I wouldn't advise just cutting it off or swapping wires john PS I did however do that to mine and fitted the internals into the ashtray for inconspicuous mounting Quote Link to post Share on other sites
barber007 Posted October 19, 2009 Author Report Share Posted October 19, 2009 When you say he has changed the polarity of the car has he sorted the dynamo etc not just swapped the battery terminals over!! I know it's a silly question but!!!!! Roger Hi Roger - not silly at all! And yes my hubby has sorted the dynamo. I was very impressed with him - it is all a bit beyond me, think I will stick to the household chores!!!! Jane Quote Link to post Share on other sites
unclepete Posted October 22, 2009 Report Share Posted October 22, 2009 Just bought a 3 way socket adapter from halfords, cut off the cigarette plug, wired it into the cables behind the dash and leave it loose in the glove box! Have had the Sat Nav, Phone Charger and a CB radio all plugged in without a problem. The 3 way socket has a built in fuse. UnclePete Quote Link to post Share on other sites
Andrew Smith Posted October 25, 2009 Report Share Posted October 25, 2009 Unc Is your 'preference' positive or negative? Cheers Andrew Quote Link to post Share on other sites
unclepete Posted November 15, 2009 Report Share Posted November 15, 2009 Unc Is your 'preference' positive or negative? Cheers Andrew Andrew you know me, i don't really care which way! Unc Quote Link to post Share on other sites
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