Adventures in TMCC & Legacy... Trying to master the 455Khz track signal. I've built the test car, and it is finally working..

Dale, without going through all 30+ engines on the layout, I have arrived at what I think is a pretty fair generalization based on observed signal strength and engine behavior. Below 32 or so is flat out bad. Readings of 33 to 45 are marginal, and 46 and up is good. Of course, the stronger the better.

I'm leaning toward antenna design, placement and orientation as the key to solving this problem. I want to play with those variables on the test car to see if this theory holds water. As I mentioned earlier in this discussion, I have some early TMCC engines that don't suffer from these signal issues, and I noticed that their antennae are of a vertical, nose mounted design, very different from the horizontal top mounts commonly found in newer diesels.

Elliott,

I just read this entire thread over the past three days. I felt as though I were back at the Purdue Electronics Lab troubleshooting our experiments! It has been quite a refresher for me. I want to thank you, Dale, John, Stan, Bob, Chuck, et al for your contributions.

Among the items I discovered is the "TMCC Signals Basic", by Dale M., dated August 2, 2011. I had learned about this from a different source, but Dale explains it very clearly in his document so anyone should be able to easily understand it, I believe.

Based on some of the discussions posted, I consider myself rather lucky in that save for one instance, which I readily solved with an added earth ground wire, I have had zero problems with Legacy. I run both DCS and Legacy without issues. Though not as large a layout as yours (Elliott), mine is no too small - the train room is 33 x 38-ft and most of it is occupied by the layout, on three different levels; or four if you count the smaller subway loop. I have over 900 feet of track, 58 turnouts, and about 26,000 feet of wire, and I am not done yet with the wiring.

Why so much wire? Because a run from the control panel to the 'other side' takes 120 feet of wire going around the edge of the room. The average run of wire is 80 feet, and given the number of power feeds, sensors, turnout controls and signals, and relay control, the wire added up very fast. I have run the last few drops to the 'other side' over the ceiling, and this saved about 60 feet of wire per run. I also have about 20 wall warts of various voltages, connected to remote-control outlets, scattered throughout the layout for lighting and for accessories.

Given all the wire running under the layout I guess I am lucky in not having any signal problems with Legacy?

 Thank you all!

Alex (Alexander Müller)

Big_Boy_4005 posted:

Dale, without going through all 30+ engines on the layout, I have arrived at what I think is a pretty fair generalization based on observed signal strength and engine behavior. Below 32 or so is flat out bad. Readings of 33 to 45 are marginal, and 46 and up is good. Of course, the stronger the better.

I'm leaning toward antenna design, placement and orientation as the key to solving this problem. I want to play with those variables on the test car to see if this theory holds water. As I mentioned earlier in this discussion, I have some early TMCC engines that don't suffer from these signal issues, and I noticed that their antennae are of a vertical, nose mounted design, very different from the horizontal top mounts commonly found in newer diesels.

Elliot

Have you tried to run a new earth ground wire under a portion of lower level, the same way you have it run on the upper level, as one signal wire (make sure the earth ground wire is not a closed loop).  Also disconnect the existing earth ground wire you have on the lower level.  There could be a problem on the way the lower earth ground wire is run/connected causing your problems.  We ran across similar issues at the club and now every time we modify the earth ground wiring, the earth ground signal test car and scope is attached to the layout to check reading before and after we make changes.  Checking a portion of the lower earth ground wire system may be easier than opening engines to check/update antennas.

If you do get into the mode of updating engine antennas, I found using 3M 1/2" or 3/4" copper tape as an antenna replacement provided better signal strength readings than the same length of copper wire.  You can do your own experimenting with different antenna type with the earth ground signal car you built.  Just add different types of antennas to the existing antenna in the signal car and read the new signal strength on the meter.  If anyone uses copper tape in their engines, make sure that you don't rely on the adhesive on the tape to hold the it to the plastic body, use a thin  coating of silicone adhesive on top of the copper tape to insure it does not peal off the shell and short out engine boards.

Good luck,

Bob D

NJ hi Railers

We know we can only have one command base, however is there any advantage or disadvantage of running more than one wire from the "U" connection to different locations on the layout.   ??

Gregg posted:

We know we can only have one command base, however is there any advantage or disadvantage of running more than one wire from the "U" connection to different locations on the layout.   ??

Gregg, in my case the TMCC and Legacy bases are located in the center of the room. There are two power supply panels. The track ground wires radiate out from there. There is a connecting wire between them, and the Legacy output is connected to that. So, even though there is only one wire connected to the base itself, there are still multiple paths down stream.

Bob, thank you for sharing all of your knowledge and experience here. I have read all your posts as we've gone along. When I'm actually ready to do some real work on this project, I will go back and reread everything. If you think of anything else, by all means, say so.