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

So the original run did not have this adjustment capability?

It wasn’t a big issue, some of us just added a pot and John added it to his product at about the same time

@Stackm746 posted:

So the original run did not have this adjustment capability?

Nope, it wasn't until a bunch of them were in the field that we started getting reports of them affecting the DCS signals.  Then Jon Z. chimed in and said the sensor tracks would have a problem with too strong a TMCC signal.

Thus the amplitude adjustment feature was born.

I am just installing DCS and am having issues.   Is there a way to retrofit?

@Stackm746 posted:

I am just installing DCS and am having issues.   Is there a way to retrofit?

Send me an email and I'll send you the instructions and the parts required.  It's an easy retrofit.

I'm Interested in getting one for my barn layout I'm planning. 6 different levels spread across 2 storys (5000 feet of track). So I'll most definitely need one. How much do they cost though?

that would be something to operate on

@APW Trains posted:

I'm Interested in getting one for my barn layout I'm planning. 6 different levels spread across 2 storys (5000 feet of track). So I'll most definitely need one. How much do they cost though?

It will be the Cheapest and best $$$$ that you will ever spend for your layout. I think they use to cost around $100. but don't quote me on that. I have one and it took ALL of my bugs out of my layout. the best $$$ I ever spend for the Layout.

@APW Trains posted:

I'm Interested in getting one for my barn layout I'm planning. 6 different levels spread across 2 storys (5000 feet of track). So I'll most definitely need one. How much do they cost though?

Sounds like you will likely need a boost!  I suspect you'll also need to apply some of the other approaches to minimizing TMCC signal issues.  I believe that the NJ-HR has around 7,000 feet of track, and I know they don't run TMCC without a buffer.

I sent you an email to your profile address.

I love this booster...and the variable gain is a winner.

This booster has been great for the NJ-HI Railers 30' X 180' multi level layout.  It has minimized blinking engine head lights to the point where virtually all engines run without a problem.  

While you are planning your mega layout, make sure you understand the best way to run and segregate different types of wires before you start wiring up the layout.  Wiring will make a difference on the performance of how well your engines run.

Good luck

Bob D

@gunrunnerjohn posted:

Sounds like you will likely need a boost!  I suspect you'll also need to apply some of the other approaches to minimizing TMCC signal issues.  I believe that the NJ-HR has around 7,000 feet of track, and I know they don't run TMCC without a buffer.

I sent you an email to your profile address.

Yup.  We have 7000 feet of track and we've been running the buffer since John put it out.  Before that we were running Jim Lefebreve's analog (tubes!) TMCC booster (which I believe was the inspiration for Dale's buffer.)   Even with that the TMCC signal can be iffy in places so we've spend a lot of time running ground wires on telephone poles ABOVE the track.  It's made a huge difference in problematic areas. Especially in tunnels as a lot of our scenery is made from wire mesh (Faraday cage!)  I emphasis  above as in the past there was a thought that a "ground plane" under the track was the way to go.  But no!   The outside rail and the diecast boiler of steamers can block this signal.  Diesel antennas tend to be on the top of the engine and steamer antennas tend to be the boiler handrails so above them by a couple of inches is the way to go.

I attached a hints and tips sheet I put together after several discussions with a Lionel electronics engineer who designed the latest Legacy engine radios.  He reviewed it and gave it his unofficial stamp of approval. We worked with him on beta testing the radios that went into the VL Bigboys and from then on.

We've used his points whenever possible and we now  have pretty reliable TMCC/Legacy operation.

While I was putting this together Bob D. from our club posted about the importance of wiring segregation.  We're talking about the same thing.

Good luck with the build and make sure you post progress pictures!

I'm going to post the work in progress track plan file for anyone who wants to take a look. I'm going to make a new topic thread for this instead of hijacking this one. So feel free to discuss with me on the new thread.

So if running common and power together creates capacitance yet dcs recommends running power and common from TIU to track as a side by side twisted pair how does one choose between the two seemingly opposing wiring recommendations?

Greg, the power and common aren't the problem with TMCC, it's the outside rail to earth ground distributed capacitance that attenuates the TMCC amplitude.  TMCC doesn't care if you short the outside and center rail together, you'd just have trouble powering the train.

Thanks, I have my ground under the overhead tracks.  Its just one for 3 tracks.   There is a 1/2" plywood and 1/2" foam and 1/4 inch roadbed plus the gargraves ties under the rails which is probably 1.5 to 1.75 inches to the middle track it is under.   So is that far enough not to trigger attenuation?   Is one ground wire sufficient for all 3 tracks?   I will have the signal buffer as soon as it arrives with your modifications.

Thanks,

GREG.

Yep, the effect decreases as the square of the distance, by the time you get to a couple inches, it's a total non-issue.  You just don't want the earth ground right next to the rails.  One earth ground centered above the three tracks should be plenty.

@Stackm746 posted:

Thanks, I have my ground under the overhead tracks.  Its just one for 3 tracks.   There is a 1/2" plywood and 1/2" foam and 1/4 inch roadbed plus the gargraves ties under the rails which is probably 1.5 to 1.75 inches to the middle track it is under.   So is that far enough not to trigger attenuation?   Is one ground wire sufficient for all 3 tracks?   I will have the signal buffer as soon as it arrives with your modifications.

Thanks,

GREG.

As John said that should be good but there's only one way to tel.  Run!

Good luck!

@gunrunnerjohn posted:

For a CAB2, I've used a hi-gain antenna on the command base, and on one instance, I actually used a 2.4ghz WiFi amplifier on the command base.  That really increased the range, and for really large layouts, it would probably be a significant help.

I can't believe I just lost signal (control) at 25 feet from the command base.  Yes, my body was between the remote and the base... but, it's such a dinky layout.  I did set up the LCS wifi  the other day could that have affected it?   I have a few spare high gain 2.4ghz antenna... I'll give them a go this weekend.

You are doing better than I am. I can only get 8 feet of range on my CAB 2  and if i put my body between the base and the remote it drops to 4 feet.

Basically a totally usless device. I use my wi throttle on the iphone through JMRI and that works perfectly from anywhere.

@Jim LeFevre posted:

You are doing better than I am. I can only get 8 feet of range on my CAB 2  and if i put my body between the base and the remote it drops to 4 feet.

Basically a totally usless device. I use my wi throttle on the iphone through JMRI and that works perfectly from anywhere.

You have an issue with either the CAB2 or the command base, that's clearly not normal operation!

GRJ,

is there any chance that the new Base 3 might have Legacy Signal signal strength improvements already built-in that we no longer need our separate Signal Booster?? I still continue to get better / more reliable Legacy signal strength thru Dale’s / your designed board.

Carl J

I truly have no idea, but I suspect they probably stuck with what Legacy offered if I were guessing.  We'll just have to wait until I can test one to see.  I'm sure the shop will get one and I can borrow it for a 'scope test.

GRJ,

Thanks for the feedback!

Carl J

I finally installed the signal booster after GunnerJ upgraded my unit with a variable strength control.    Unfortunately I still have issues.   If I turn the booster up all the way, I have no issues with Legacy/TMCC.   However my DCS units loose their horn, bell and speed control in many areas of the layout.   When I turn the signal booster down to about half way, the DCS works again but my Legacy locomotives stall in a few places where they are below other tracks.   I have attached a layout wide ground wire to the ground connection of the booster unit and run a copper wire atop the lower level, but this does not seem to work.   The areas that have issues have 2 adjacent tracks.    Might running the ground wire connection between the tracks also help?

Any other ideas on how to get both systems operational on my mainlines.

Thanks for your help.

GREG in Wisconsin.

@Stackm746 posted:

I finally installed the signal booster after GunnerJ upgraded my unit with a variable strength control.    Unfortunately I still have issues.   If I turn the booster up all the way, I have no issues with Legacy/TMCC.   However my DCS units loose their horn, bell and speed control in many areas of the layout.   When I turn the signal booster down to about half way, the DCS works again but my Legacy locomotives stall in a few places where they are below other tracks.   I have attached a layout wide ground wire to the ground connection of the booster unit and run a copper wire atop the lower level, but this does not seem to work.   The areas that have issues have 2 adjacent tracks.    Might running the ground wire connection between the tracks also help?

Any other ideas on how to get both systems operational on my mainlines.

Thanks for your help.

GREG in Wisconsin.

DCS and TMCC are not truly compatible. You can read the old post that gets into the details about this.

If you get an oscilloscope you can use this handy diagram I keep posting to help you tune this out. Basically you need to get the balance between them "just so".

This is easy on a small layout but on a large layout the signal levels vary too much from one end to the other to get a good balance everywhere at the same time. At our AGHR club we built a system with multiple feeds to the layout with closed loop phase-shifters to balance out the feed phases to avoid self-interference.... this is to solve EXACTLY your problem. It's complicated but it works. You can see that feed setup in our AGHR circuit tour. (specifically this doodle is helpful)

In addition to Adrian's comments, I'd suggest you first run the "earth ground" wires to minimize the signal strength issues, then add the buffer and tune it to the best performance.  The buffer can only address global issues, if you have local weak signal spots, it's best to minimize those before boosting the signal everywhere.  The trick is to get better balance on the signal.

Also you need to be reasonable, if you have a giant layout and 100 locomotives, but only 1 or 2 have signal issues, you may be better off looking at the locomotives themselves to see if you can add some metal and get better field coupling back to the Earth ground.

Touchups with ground wires work well (at the cost of being ugly).

Also one big thing is for the GRJ booster and legacy base itself is make sure they aren't plugged into a GFCI plug or power strip which has extra circuity in the ground for circuit interruption that 455 KHz doesn't like flowing through.  We saw some super weird stuff with a few brands of power strip.

I am using several power strips and all receptacles in the train room are GFCI. I have no problems. There is no circuitry in any power strip or GFCI the in any way inhibits anything in the GROUND signal path. The Grounded conductor and Hot conductor do go through some filters and surge devices in power strips. There are no surge devices or filters in Ground Fault devices either breakers or outlets.

You description of the problem also is not clear. Ground wire to what?  FRom where ?

Do not ground the tracks, anywhere.

I'm talking about this grounding  impedance. With the spectrum analyzer or even just time domain scope we see with some power strips or GFCIs we develop the voltage Zs/(Zs+Zo) x V between the ground terminal on the booster and the true building ground, where Zs is the series impedance added by the strip, booster or even just inductance off a long return wire.... Zo is the output impedance of the booster itself, and V is the output voltage of the booster V = Vo cos(wt) where w is 2 x pi x 455 KHz respectively.

Since the booster has finite output impedance Zo, and finite output Voltage V, that means that to satisfy KVL that any voltage being developed in the ground path scaled by Zs/(Zs+Zo) is coming directly off your output scaled by [1-Zs/(Zs-Zo)]. It's a loop so:

V[1-Zs/(Zo+Zs)] + V [Zs/(Zo+zs)] -V = 0   (KVL!)

Some of the dollar store terminal strips did really poorly... and that makes sense... the output Zo of the booster is a low number as it should be since it's intended to drive a rather large load (lots of capacitance), so even a low series resistance in the return path can have a pretty dramatic effect on the series combination Zs/(Zs+Zo)

You are certainly correct about some of those cheap power strips. Some of the ground jumpers are just pop rivets internally. GFCI are different however. Neither in a GFCI breaker or CFCI receptacle nor an AFCI device does the ground wire go through any snesors or electronics in the device. The ground wire is ( or should be ) a totally seperate conductor and goes only to the round ground prong on the receptacle and does not even go near the device in a panel board containing a breaker. I have seen a lot of houses wired incorectly where the grounds and neutrals were interconnected in various places. This is a code violation. The building can only have one point where the grounded conductor and the earth conductor ( grounding conductor ) can be connected and that is at the service entrance panel. May larger houses have a sub panel or 2 off of the main panel and people ( and licensed electricians ) connect the ground and neutral together at the sub panels. That raise the ground above the true building ground point. It is also for the power incoming to raise the building above true ground due the the current draw for the incoming utility. Drive a ground rod into an isolated point in a yard and them measure the impedance to the main service entrance ground of the house. Can be an interesting reading in some cases. The purpose of the common ground point is at one point only in a dwelling makes the effect of a bird on a wire. If the whole building is above true ground it is not a problem since the frames of refrigertors and other things is what you could touch. BTW driving and isolated ground rod and bringing that conductor into a house without bonding it to the house main bond point is a code violation.

Jim

Thanks to all for their input so far.   First, I have a 12 gauge extension cord that goes direct to a 20 amp circuit and has an embedded 3 way 3 prong splitter on the end.    I have both the legacy base and booster plugged into the splitter.    Each has a small on off switch between their plug and the extension cord as there is no switch on the cord and the circuit plug is well under the layout with no master turnoff (mistake on my part).   I have my master ground wire in the wiring run of the power runs with the common on the the other side of the layout.   The master ground is connected to the ground receptacle of the of booster.   Please LMK if there is a better connection point.    That being said, I do have an actual earth ground in the room that goes into the house master ground if connecting to that might be a better solution.    I was told by someone that it had to be part of the actual electrical ground but I am unsure if that is correct.   Please enlighten me on that.

The areas with the problems have several parallel tracks on the lower level where the problem is as well as on the upper level.    My ground plan shield is run under the upper level on the bottom of the plywood and above the lower level.    Now the copper ground wire is run roughly in the middle which means there are 2-3 tracks on each side of the ground wire.   Not sure I need to run additional ground wires either between the upper or lower tracks or a parallel run directly over the problem areas which are on curves.   LMK.

I will look for my ohm meter and see if I can detect any ground on the tracks themselves.

Thanks for everyone's help.

So my problem is not consistent across the layout.   When I turn the signal booster up to the point where legacy has no stalls, the DCS does not work for horn, bell and overall speed control.   The DCS trouble spots tend to be on the lower level or near a cross under and never on the top levels.   This is what I would expect from legacy but not DCS.   I limit my DCS blocks to no more that 10 tracks and the 16 gauge wire runs to under 30 feet.   Yet it works fine in some areas but not in others.

Any thoughts on why that might be?   I understand Legacy is making DCS unstable but why might it different in different part of the layout for DCS?   Do I need smaller blocks or wire runs?

Thoughts on reasons and remedies are appreciated.

@Stackm746 posted:

So my problem is not consistent across the layout.   When I turn the signal booster up to the point where legacy has no stalls, the DCS does not work for horn, bell and overall speed control.   The DCS trouble spots tend to be on the lower level or near a cross under and never on the top levels.   This is what I would expect from legacy but not DCS.   I limit my DCS blocks to no more that 10 tracks and the 16 gauge wire runs to under 30 feet.   Yet it works fine in some areas but not in others.

Any thoughts on why that might be?   I understand Legacy is making DCS unstable but why might it different in different part of the layout for DCS?   Do I need smaller blocks or wire runs?

Thoughts on reasons and remedies are appreciated.

This doodle may be helpful to you. doodle

I've had a few requests for more of these, however I'm out of parts and boards.  If you are interested in one, please send me an email.  If I get enough requests, I'll see about getting another set of boards and parts and assembling one last batch.

I can say the prices may be higher, the plastic case I used has all but disappeared, and the only one I found in a search was three times the price I was paying before.  If that disappears, I would likely have to change the board form factor for a new size enclosure, that will run up to cost as well.

The same situation for the 24V power brick, prices have tripled for the same product.

Component costs have also gone up significantly in the two years since I last ordered parts for these.

GRJ,

I have a complete NIB V1.1 booster, power supply, instructions, and cable that I never used. (I solved my signal problem by adding more home-run wires to the far reaches of my train yard.) If you have a customer in desperate need for one, I'll be glad to ship mine out to them. I'm not looking to make a profit.

Bruce, I've had several people ask about them, maybe post it in the For-Sale forum?

@gunrunnerjohn posted:

I can say the prices may be higher, the plastic case I used has all but disappeared, and the only one I found in a search was three times the price I was paying before.  If that disappears, I would likely have to change the board form factor for a new size enclosure, that will run up to cost as well.

John,  Do you have the dimensions for the plastic case?  It may be a candidate for 3D printing.

Well, the case outside dimensions are 103 x 64 x 40 mm and there are bolsters inside for mounting the board.  I'm sure it "could" be 3D printed, but I suspect something that size would be fairly expensive.  eBay: 255542321455 is the case I was using, but it was only a couple bucks when I bought them in quantity.  I suspect that was a huge production run a few years ago, and they were plentiful from a variety of sources.  Now that they're down to the dregs, they're pricing them way higher, $5.77 + $1.66 shipping, three times what price and shipping was when I bought them.

If you do get into a pinch... I saved the photos off the site and if you can get the internal dimensions (or, design your box if you want) ...I've got a couple 1 kilo spools of PLA filament that I'm not going to use.  So the cost would be somewhere around 0.