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Nearing completion of the design and procurement phase of a new 3 level 9' x 19.5' layout with multiple power districts and blocks for simultaneous Conventional and Lion Chief independent controls of 3 primary track loops plus independent siding/yard operation. Power and control will be primarily handled with 2x PW 275Watt ZWs, a combination of rotary and double throw switches/relays, with options for accessory power from additional small transformers. Yes this will be somewhat complex, but I enjoy keeping track of signal flow and the speed, look and tactility of lots of physical controls. I think I have a firm grasp on this part.



In addition to conventional and LC control, while building the layout I would like to incorporate electrical infrastructure that will make adding Legacy (and maybe DCS) afterwards go smoothly (ie. not having to remove or re-do what would already be in place.) I've been reading a lot of great information on Legacy (and to a lesser extent DCS) here on the forum, including parts of the Legacy manual. Right now the Legacy control system components and locomotives are beyond my budget, but the wiring for it is on hand.



In the future, if adding a ground plane to my layout to improve reception of the Legacy signal in problematic areas becomes necessary, the way I build my bench-work, it should be easy enough to add if there's an issue.



The ground plane discussions on the forum got me thinking about another possible issue that I might have with the signal, and this is the ungrounded Faraday cage around and over the layout. This Faraday cage is part of the thermal envelope I installed when turning the previously unfinished space of our 2nd floor into additional bedrooms, storage, and best of all … finally, A TRAIN ROOM!  One component of the thermal envelope is Foil-faced Polyisocyanurate insulation boards. They form a continuous radiant barrier around the exterior walls and ceiling of the 2nd story of the house (except for the windows and floor).



This barrier is also very good at blocking cellular phone reception. However, Dual band WI-FI, Bluetooth and cordless phone communication between transceivers within the envelope all seem to work fine up to their expected ranges.



While contemplating the pros and cons of earthing the cage, I quickly decided against it because I don't want to create a more appealing target for lightning strikes.



Do any of you Electrical or Broadcast Engineers foresee any issues with control signals inside this shield? If so, do you have recommendations about what I might want to consider and/or do to make future Legacy and maybe DCS integration go smoothly with respect to the Faraday cage issue?

Last edited by SteveH
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Truthfully, I don't think that will be much of a factor.  The TMCC/Legacy signal is 455khz, and since the electrical wiring will be on the inside, the earth ground we speak of as being the over the air component of the TMCC/Legacy signal will be inside this possible barrier.  At most, you might have to run a couple of earth ground lines around the layout.

I will point out that the New Jersey High Railers have a really huge layout, and they actually isolated their earth ground and don't use the power line ground lead.  I don't know if it's still wired that way, but I know that came up in conversations when I was in early testing of the TMCC signal booster that they use there.

Legacy uses the ground wire in your house wiring to transmit the air signal to engines. It’s not a ground plane, it’s just a wire in the walls...part of your house AC wiring. Can your layout see that wire without having to go through a conductive foil? If not, you might string a wire over head of your layout and plug it into the wall with a plug just wired to the ground terminal in the plug. OR connect it to the #5 pin on the DB9 connector on the legacy base.

Chuck, Thank you for rightly pointing out that it's not really a ground plane.  Would it be better referred to as a low impedance antenna?

When I wired the 2nd story electrical system, I put 95% of the wires and devices to the interior side of the radiant barrier.  There are lots of circuits around the layout area on all sides.  All branches come from a breaker sub-panel where grounds and neutrals are on separate busses.  As per NEC, Main panel has independent busses for ground and neutral, these busses have one interconnection and a connection to actual earth ground.



John, The notion of isolating an independent earth ground for the Legacy system is interesting.  Seems like this would reduce interference caused by transients from large household and external inductive loads and other sources of RF Noise competing with the Legacy Signal, maybe?  Did the NJ Hi-railers have other reasons?

Last edited by SteveH
@SteveH posted:

Chuck, Thank you for rightly pointing out that it's not really a ground plane.  Would it be better referred to as a low impedance antenna?



Just antenna I guess. A few years ago folks were putting foil under the upper track to help the lower track kind of because of the word "plane" which adds a lot of capacitance you don't want. Then Dale M suggested we make an effort to drop "plane", but it is so catchy, it's still around.

I call it the earth ground.

Chuck is correct about the capacitance.  One of the issues of running too much ground wire is the coupling between the outside track and the earth ground of the command base.  This is one of the issues that the TMCC buffer that Dale designed was designed to address.  As we all know, sadly Dale's untimely passing meant he wasn't around to see how well his design worked.

TMCC/Legacy Track Signal Booster (Dale's Legacy Continues)

I've run modular layouts in many steel Morton buildings that do a fine job of suppressing outside communications.  No problems with TMCC/Legacy.  AC wiring (TMCC ground) is on the inside of the metal shell.  I have a set of 3-wire extension cords that provide an extra ground wire when run under modules but have only needed them once - in a cavernous metal exhibition center where AC power is in conduits and under the cement floor.

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