Feedback contacts planning

[Moris]

Hi all,

since I'm still planning the conversion to "computer controlled operation" of my layout, after my previous question (see http://www.windigipet.de/foren/index.php?topic=61677.0), I have another question regarding the routes.

If I understood correctly, every route should normally have four section as in this way:

  |--start--|-------travel----|--brake--|--stop--|

and the start, brake and stop section should always contain at least one feedback contact. Transferring this concept in a real layout, is it correct to say that the FIRST track piece of a given section will contain a feedback contact...? (in other words, that it will be a contact - or circuit - track...?)

And what happens if I plan to have bi-directional traffic on a route? I understand that the start section in a direction becomes the stop section in the opposite direction as in this way:

  |-start/stop-|--brake--|travel|--brake--|--start/stop--|

but is a single feedback contact (e.g. contact track) enough for one start/stop section, or have I to plan additional feedback contacts due to bi-directional traffic...?

May be that I am a little confused because I haven't tried yet to put these concepts in a pratical environment (I have only tried Win-Digipet 2009 Demo), but the only thing I have understood is that the right planning and positioning of feedback contacts is fundamental for a correct operation of Win-Digipet, so I'd like to learn how expert Win-Digipet users usually plan the positioning of feedback contacts in their layouts.


Thanks for your help and any other related tips.

Maurizio

[Stefan Lersch]

Hi Maurizio,

each section is one feedback contact. That means: the start conctact e. g. may consist out of let's say three tracks. These three tracks are one feedback contact. You make isolations between the start contact (= start section) and the preceding and following sections but not in the start section. Result: a locomotive may be placed on any of these three tracks and no matter where it is placed WDP will get a feedback.

The same is correct for every other section no matter how long (how many tracks) a section is. This is the simple case.

In the more advanced case you do not have start | travel | brake | stop but start | travel 1 | travel 2 ... travel n | brake | stop. Of cause you can make it more complicated and may also have start 1, start 2 etc. Same for brake and stop. In my opinion it can make a lot of sense to divide the travel section into numerous sections. In that case you can e. g. define different travel speeds for each section. But in my opinion it doesn't make much sense to divide the start, brake or stop sections.

By the way: the stop section of the first route is the start section of the next route.

Concerning the bi-directional traffic: you are right. You only need one contact for start/stop.

There are a lot of WDP layouts in this forum. The description of the layouts is only in German available but anyway you can see how other WDP users planned their layouts. Please have a look here: http://www.windigipet.de/foren/index.php?board=19.0

If you can than start with a very simple example. Take one easy route (maybe without turnouts) and try to make a WDP route. The best way to learn it is always to make it yourself. Give it a try and if you have any questions or problems please do not hesitate to ask!

[Moris]

Hi Stefan (and all),

thanks for your quick and exhaustive reply.

each section is one feedback contact. That means: the start conctact e. g. may consist out of let's say three tracks. These three tracks are one feedback contact. You make isolations between the start contact (= start section) and the preceding and following sections but not in the start section.

This is a concept I completely misunderstood. But this worries me a bit too.

If I understand correctly, this means that I have to modify (e.g. cut the ground latches of Märklin C-Tracks as from Workshop 11) almost all my tracks (except from the switches), or I caught it wrong...?

I'll try a drawing:

               |                     section A                     |                     section B                     |
  ---------+------------+------------+------------+------------+------------+------------+--------
                     24xxx           24xxx           24xxx           24xxx            24xxx           24xxx
  ---------+------------+----------+-+------------+------------+------------+------------+--------
              ^                                 |                    ^                                                      ^
              |                                  |                    |                                                       |
          insulator                            |                insulator                                             insulator
                                                 |                                         
                                     sensing wire to Mä s88 or similar   

So:

- all tracks have the two outer rails insulated from each other
- the ground path for all locomotives relies only on one rail

Sorry for the silly questions, but I have to be sure to have understood this correctly from a pratical perspective, because it involves a lot of work in the (re)building of the layout.


Thanks again for your patience.
Maurizio

[Stefan Lersch]

Hello Mauritio,

you understood correctly and your drawing is correct, too. You need insulations between the sections but you do not make any insulations within a section. In your example you have 2 feedback contacts (A and B).

I can't answer the question where you have to make the insulations at Märklin tracks. I have N gauge which is DC but I am sure someone else can answer this.

PS: there are no silly questions in this forum!

[Ralf Krapp]

Hello Maurizio,
you are right, you have to cut the underground connections of the outer rails so that you will get an isolatet rail on one side of the track. The other side is the ground path which will be not cut into sections, even when two or more boosters are installed (excepted when you use CS1 or CS2; note the special rules for application in the brochure).
It's right, that after this modification of the track only one side is used for ground path. But don't worry about, it will work. To be sure that all locos will run without interruption and start correctly in a stop section you can use a diode to be installed between the outer rails with the ring showing to the isolated rail (= feed back side). Diode should be of a type like BY 500/200.
Perhaps you may read in "Hints and Tricks" the topic of "better ground pick-up".

[Moris]

Stefan and Ralf,

thanks again for your help, now everything is  more clear. My only concern is about the fact that I'll have to modify almost all my tracks, but I suppose this is a problem that affects all C-Track owners.


Maurizio

[Ralf Krapp]

Hello Maurizio,
you are welcome. It's correct that all C-track owners will have this problem. I suggest the following modification: cut the connections of the outer rails on both sides of the track and bend these connectors a little bit aside so that they will not get in contact again. In the case you will restore the original situation you bend these parts back again and solder them. But I guess that you will have no need to do so.