Power at rails or at supply?

[proxieken]

I recently added a variable regulated supply to the track. Kind of a long story- but the big monster supply from the 60's was unregulated so it caused some problems.

Anyhow, I am testing and have about a 1.6 volts drop between the power supply out wires and the rails on the track. I am assuming this is due to resistance in the length of the track. It is 75' long. Do you turn up the power until you are getting 18 volts at the rails? It is a Carrera Digital track and I do not want to fry the control unit. The power supply has variable amps so I set them at 6 max to protect it.

The thing is, when I plug in the standard Carrera supply I am seeing a similar drop. I get 18.5 at the supply but about 16.2 at the rails. So I am thinking Carrera designed the drop in with the track design. So the cars are supposed to run on 16?

Just wondering if the voltage drop is normal and if it should be compensated for.

BTW. I really know very little about what I am doing and will most likely destroy something soon. I am learning fast thanks to reading forums and asking questions.

:oops:

[dr fabio]

Dont really know the digital system that well, but from my understanding there is always max voltage at the rails and a signal is superimposed on the rails and decoded by the chip to allow the voltage through to the motor on the car. I assume that when you say there is a voltage drop at the track that you measured this under no load conditions? That is you measured it when there were no cars running on the track? Under such conditions you should not measure any voltage drop due to poor (resistive) connections between the power supply and the rails. Voltage drop due to poor connections is V = IxR. With no cars on the track there can be no current flow hence no voltage drop. So I suspect that the voltage drop is due to the way the digital circuit works and is normal.

[MrAdept]

Just measured mine and I see about 16.7V on the rails out of my 18V Carrera power pack.

To see the voltage drop on the track measure the voltage at the furthest point out, (half way round or so), and compare with the measurement right at the power track. You may need to have a car/motor running to add some current draw in that area when you are measuring. That should give you an idea of what is dropping through the connections between track pieces.

Mark