Help for a newbie - points control

[stephjant]

Hi, I'm new to this forum and new to the hobby. I know little about electrics, so if anyone is minded to respond to this post please respond in simple layman's language. Before starting this new thread I did look on the forum but couldn't find what I was looking for.

I have laid my small N guage track, got a loco and tested its operation with my new Hornby DCC select controller. I have also laid 5 PECO turnouts, and each one has a PECO PL 11 motor (fitted but not yet wired).    My options for controlling the point motors electrically seem to be a) use my new DCC controller and purchase the Hornby R8247 Accessory Decoder (which I know can only operate up to 4 points) or b) use separately powered and operated point switches and CDUs. 

My question is this: how is the Accessory Decoder connected to the DCC controller?Is it simply a case of connecting the 3 wires from each of the points motor to the Accessory Decoder - and then connecting the Accessory Decoder to the Auxilliary Ouput at the back of the DCC controller?

Knowing the answer to this question will help me decide which route to take to control the points. Thanks in advance for any responses

[Chrissaf]

Is it simply a case of connecting the 3 wires from each of the points motor to the Accessory Decoder - and then connecting the Accessory Decoder to the Auxiliary Output at the back of the DCC controller?

 

You have almost got it right but not quite.

 

A DCC Accessory Decoder such as the R8247 is a DCC device which is also a DCC decoder ... the clue is in the name. Therefore it has to be connected to the 'TRACK A & B' output of a DCC controller [i.e your Select] not the AUX output.

 

The AUX output [in the case of a Select] is a 15 volt DC output [not DCC]. It is used to power Analogue DC products not DCC ones. However that said, when using the Select with its factory supplied 1 Amp power supply, it is advised ideally not to use the AUX output, as any significant electrical current [Amps] drawn from the AUX output is deducted from the DCC current that is available from the Select to operate DCC locomotives. The one exception for that statement is, if you were to connect the AUX output to a CDU to operate the points via electrical switches. A CDU [Capacitor Discharge Unit] is charged up by a low level trickle current from the Select AUX output, the CDU then stores a high current charge to operate the points. The trickle charging current impacts very little on the current available to operate locomotives.

 

Personally, with only 5 points. I would operate them using traditional DC Analogue methodology with a CDU and manual switches. Do not use the Hornby R044 points switches as these are not 100% compatible for use with a CDU.

 

For DCC operation. You could use either 2 x R8247s for your 5 points [4 ports spare] or a single DCC Concepts ADS-8SX Accessory Decoder that has 8 ports.

 

But bear this in mind. When you operate a point via a CDU and a physical switch [and there are only 5 switches to worry about] it is quite straight forward and needs little operational forethought.

 

If you operate those 5 points via DCC using the Select, each of those 5 points will need to be given a separate unique DCC address. You then have to memorise those 5 addresses or have a written 'aid memoir' nearby to refer to.

 

Then when you want to operate the point you have to use several key strokes on the controller to call up that address and operate the point. If you need to set a 'route' involving more than one point then you have to replicate those tasks for each point in the route. All the time you are using the DCC controller for the point operating tasks, you are unable to use the controller at the same time to operate your locomotives.

 

DCC is very much one operational task at a time control.

 

Where DCC control comes into its own for total layout control. That is to say, locomotives, points and signals. Is when you are using a PC software based controller such as Hornby RailMaster with an eLink or Elite. RailMaster can't be used with the Select controller.

 

So based upon the above, my advice is that if using a Select with only 5 points, that the points are operated using traditional DC Analogue methodology. Only one CDU is required as it is a shared resource for all the points. Not only that but PECO PL-11 point motors have come up on the forum before as not working reliably with the Hornby R8247 Accessory Decoder, thus they are more likely to operate robustly and reliably using a traditional Analogue CDU method.

 

Some schematics that will assist.

 

DCC Control using Hornby R8247 [note that in this schematic it shows Hornby wiring colours and Hornby Motors as it was copied from a previous reply elsewhere on the forum].

/media/tinymce_upload/c0cb6423b00805be12a546f134aedcf8.jpg

 

DC control using Select AUX output and CDU [note that in this schematic it shows PECO wiring colours and PECO Motors, again the image was copied from a previous reply].

/media/tinymce_upload/1691b95fd355aaef3cc0266c82a0fe6f.jpg

The switches could also be PECO PL-26 lever switches which are totally compatible for use with a CDU.

 

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[stephjant]

Thanks very much for the response, very helpful