Carrera polarith

[MikieG]

So my buddy added a nice power unit to his analog Carerra track. He can dial amp/volts as he wishes.
Today I noticed that when I sat my car on the track, it took off without me on the trigger. He said it was because the track is now opposite polarity and for me to switch the black and the white leads. I did so, and all was fine.
So I am fixing to order the PM club racer super pro controller. It says it is Positive polarity. Is this the one I need? Any experience would be appreciated.

[Dangermouse]

As best I understand it all - for positive polarity the positive feed from the power supply goes to the right hand rail of the slot with the car facing in the direction of travel.

[RichD]

If you are using an electronic controller those are polarity sensitive. That has nothing to do with the track rails, it has to do with which way electricity goes through the controller. Devices like transistors and diodes only conduct in one direction, so the polarity of the controller has to match the way that the track is wired. Usually electronic controllers are designed so that they will not be damaged if they are connected to a track with the wrong wiring. Some electronic controllers will only work with a track that is wired for brakes. If you are unsure about the polarity of your track wiring or your type of controller just connect the black and white wires and see if that works, if the controller has a red brake wire do not connect that. If the controller does not work switch the black and white connections and the controller will probably work. In that case if you have a brake wire do not connect it, you would be likely to short something out. If the normal connections work it is safe to connect the brake wire. If the track and controller do not match it would be best to change the polarity of your track wiring, that is fairly easy to do. Just switch the wires at the power supply and switch the wires that go to the track rails, your cars will still run in the same direction.

[RichD]

I should add that set type 1/32nd tracks all have what is called negative polarity and most club type tracks have positive polarity. Here is what each type looks like.

First negative polarity.


Here is positive polarity.

[WB2]

Why was this never standardized way back when?

[RichD]

I guess that before there were electronic controllers it did not matter, resistor controllers conduct in either direction. A local commercial raceway had three tracks and two of those had positive polarity wiring while the third had negative polarity wiring. Years ago I raced on an oval track where some lanes were positive polarity and others were negative. One of the racers used an original Professor Motor diode controller and he had to remember the correct hookup when he rotated from lane to lane. The majority of electronic controllers are made for positive polarity tracks, some makers offer both polarities. There are a few dual polarity controllers where you can flip a switch or swap a couple of wires. I have a couple of old Cidex Omni controllers, they are like diode controllers, but they use bridge rectifiers and work with either polarity without having to do anything.