Hi Alex
Here are remarks (just my personal opinion):
- current sensing is good for 2 rail operation but in 3 rails, this is definitely an inferior solution. Why, because only slider-equipped vehicle are detected. At least, in 2 rails using a resistive paint on the axles, you may detect ALL vehicles
- isulation using C Track: the best way is to use the red sleeves 74030 and to cut the rail 2 electric bridges. I used a diamond disk to cut the rail in very precise locations (uncoupler operation, etc) but it has drawbacks: difficult to do it in-situ, leaves metallic dust that is good for ghost detections, it is irreversible, takes time. So I am not a big fan of this.
- to be fair, using Märklin sleeves 74030 has its drawback: sometimes the rails supposed to be insulated are so close that it makes an unwanted contact (using old C-Track, using it near the start of a ramp), there are easily damaged and should be replaced without hesitation (happened to me that re-using those sleeves has caused un unwanted detection after quite some time. In few cases, I had to file rails to avoid unwanted contacts.

I hope this helps
Jean

You have to cut the strap between the rails if you are using s88 style train sensing where the wheels are bridging the the rails together. Remember there is a strap at both ends of the track piece, and both need to be cut.

If you are using some other scheme then maybe you can get away without cutting the strap.

The problem with center track sensing is cars or locos with sliders will activate the sensor so cars or locos without sliders will not be noted and the block will appear empty. That might cause collisions if you have a very long consist and a short block. Also, if your loco/car with slider goes beyond the sensor it will release the block immediately. And if the loco has a very slow acceleration you might have a collision.

If you already have a bunch of current sensing modules and are happy with the disadvantages described above: Carry on! I used current sensing when having M tracks, these worked fine.

However, then you should NOT cut any straps on the C tracks, but connect the wire from the sensing module to the middle rail. Of course, isolate the track end connector, were you want the sensing track to end.

I guess 99 % of the hobbyists on C tracks use earth sensing modules (cutting the strap between the outer rails).

The way a contact track works is cutting off the connection between the outside rails results in their being electrically isolated and remain so until the wheels of an AC car make a connection. And that occurs as long as AC cars are on the contact track. Finally if you are happy with just sensing cars with sliders you can just use a circuit track and avoid all the hassle. Plus it has the added advantage of being able to sense which direction the train is going.

Is it?

http://yamorc.de/products/?singleproduct=1244

If you intend to use Loconet as feedback bus, your Z21 shouldn’t care if you have ground sensing or current sensing modules…

Karst Drench from YaMoRC - "Z21 is not allowed to be used with Ground Detection. It will blow both Z21 Hbridge and YD6016LN-GND"

I am using YD6016LN-CS

Coming late into this discussion, but I think I should share some of my experience.

16 years ago, we built a C-track layout at my work for demonstration purposes. We decided to use current sensing to identify the position of the train on the layout (we only ran one train). We used the red isolation pieces and we had no problems with it during the 8 years we were running it. But it was a permanent layout, don't know how well it works if you rebuild your layout frequently. We used a rather elaborated current sensing method, with signal transformers to get the detection circuit isolated from the track. It turned out to be a very reliable solution. The drawback that you can only detect the loco with the slider is not a big problem in reality. The control program can know the train length and calculate which section(s) that are occupied.

We made experiments with normal contact track, it worked rather well but not with the 100 % reliability we could achieve with the current sensing method. We built the electronics ourselves so I do not know how well the commercial devices work.

I later found out that the current sensing devices that we built for the layout could be modified to instead provide MFX feedback from track sections powered by a standard booster. I have never used that on any layout though, only tested that it works.