Placement of resistors for DS-54 to Switchmaster? : LUSENET : Wiring for DCC : One Thread

Please help!

The wring diagram in the "Track Switch Control" section shows the two resistors going from each Switchmaster lead to the Green (coomon) for the DS-54. The Switchmaster instructions call for a resistor to be connected the the positive lead. I realize the DS-54 will require two resistors but shouldn't they be connected to the Yellow/Black wires from the DS-54 then to each Switchmaster lead? I'm confused, please help explain.



-- Stan Godfrey (, December 04, 1999



I haven't asked AJ what his output circuit in the DS-54 looks like exactly, so I can't give you a good answer as to why it needs to be the way it is shown in the diagram. The diagram basically comes right from the DS-54 manual. I know it's right because that exactly what I use all the time.

As far as the resistor being connected to the positive lead, that isn't necessary. It can be in series with either lead.

Allan Gartner

-- Allan Gartner (, December 05, 1999.

Stan, Allan,

May be this will help. The DS54 output is, the Green wire is the DS54 + common, the yellow/black are current sinks when turned on.

Resistors connected between yellow to green + common, and black to green + common are external pull up resistors, and are used to pull up the off output closer to the value of the + green common. In other words they supply more current to the output.

The single resistor recommend for the Hankscraft motors is in series with the motor input, and is meant to be a current limiter, to keep the speed down on the motor for a given input.

So it is not to hard to see, the pull ups are to raise the current, and the series resistor is to lower it. Do not use both together. Infact it is best to try and use the DS54 without any of the resistors. If the speed is to fast, then add a low value resistor in series with either the yellow or black to slow it down. If it is not fast enought, then instead of pull up resistors try using the AUX AC input on the DS54.

By using voltage instead of resistance or atleast nothing more then a low value resistance for series, then the outputs are much more stable then instead of having to depend on higher values of resistance.

But the one thing you do not want to do is use the pull ups and the series current limiter together.

Remember Always Have Fun and Enjoy!, Don Crano Akron, Oh NMRA #096211 Visit Model Railroading with DCC at:

-- Don Crano (, December 06, 1999.

Moderation questions? read the FAQ