Block detection

Most trains run fine on one ground rail.

Dale H

If you're using TMCC, you could have signal problems with a single ground rail. It can be fixed by adding capacitors. Lionel has a video that addresses this.

We use insulated running rails in several areas of the layout and it works fine for TMCC and DCS.

I've been looking at the CTI system myself. Can you post your experiences with it?

Thanks for the tip, after a quick Google, I found the info here

http://www.youtube.com/watch?v=UQ-hiIvPxVs

Sure, I'm planing to document everything i build 

Burns Electric, if he's still in business, sells a block detector where you isolate the middle rail.  I have one and the way it works is that it detects a change in the load in the block.  You need either an engine or a lighted car for it to detect activity in the block.

But it does eliminate having to create a bunch of outside-rail insulated tracks.

- walt

That sounds interesting Walt, it would eliminate the whole issue of insulated rails.  I don't always like insulated rails as it removes half the track common connections from the locomotive.  For smaller units that only have one or two wheels without traction tires on each side, that makes a significant difference at times.

Actually the BD-20 of NCE can detect what ever current is draw by the hot (middle) or the common (outside rail ) without insulation of the  rail. But it work only with engines, caboose or cars with lights, with DCC, you can make it detect cars if you install a resistor on the axes between the wheels. That's a no go for me, I need it to detect the cars too; if the train crew cut a train and live few cars on the track when he is switching on a siding, the main is not clear. 

Position detection seems to be a reocurring question among modellers. There are quite a number of methods available and each has its proponents and companies that offer products. I published a chart on this subject in the Sept. 2007 issue of TTOS's The Bulletin. In this chart, I outlined eight different basic approaches and described the pros and cons of each. No method is foolproof and each needs to be impemented carefully.

Bob Walker 

We 3 railers were given the gift of free detection when we  sacrificed realism. Why would we complicate the issue and resort to the method 2 railers are forced to employ?

If I was going to give up something for better ground rail contact, it would be traction tires.

P.S. The mainline on my layout 100% insulated rail for the purpose of detection. 

Could not agree more . Relays with the insulated rail method are much cheaper and more reliable. Hookup described here.

http://www.jcstudiosinc.com/BlogShowThread?id=410&categoryId=

Dale H

Dale, I love the relay method. An electrical engineer I used to know drew up a circuit that is a little more complicated than yours. It started out as just a means to stop chatter, but when trim pot was added to vary the activation time, it became much more useful. I used this on my portable layout, and some of the effects were mind boggling.

For my permanent layout I have a different plan. No relays for detection. Computer!