DM TMCC BUFFER

Before you go hauling down the path of boosting the signal, have you done proper troubleshooting and improvement of existing TMCC signal?

As an example, something as simple as extending the ground plane (true earth grounded) in the area where signal loss is thought to be occurring. Something as simple as placing an earth grounded 3 wire extension cord next to the area of suspected signal loss?

Further, because Lionel products are 110V, and thus the required earth grounded wall wart power adapter for your base must be earth grounded to achieve proper TMCC signal transmit strength- and your country uses higher voltage main line current- it's entirely possible you do not have good earth ground for the power adapter and base (when using a step down transformer).

To put it more into a checklist or just bulleted list:

• Your track system is fully isolated from earth ground because we use isolated transformers for our track power system. There intentionally is no connection to earth ground through normal hobby train transformers. This is talking about the 18V AC or variable AC transformer used to power the track and accessories and the trains that run on them.
• When using command (TMCC/Legacy) a base is connected to the outside rail with a single wire and it's expected your entire layout and track plan has contiguously connected common outer rail. Both physically, and electrically- again, the entire track is on non-conductive wood or other materials, the track is powered with an isolation style model train transformer, the outer rails of the track are then connected in common to the single wire post of the TMCC/Legacy base. This forms one side of the antenna system for TMCC radio signal at 455KHz.
• The power supply for the TMCC/Legacy base specifically is of the 3 prong American outlet style and the round prong is the earth ground. In turn, the low voltage AC (12V for older TMCC base, and 8-9V for the newer Legacy 990 style base) has the outer ring of the coaxial plug connected to that earth ground pin internally inside the transformer. Thus at the base, the power entry jack outer ring terminal is expected to be at earth ground potential. This makes earth ground the other half of the TMCC radio signal.
• Your train then sitting on the track, then frame, the wheels, and if a diecast shell is then sitting at the same common potential as outer rail, which is connected to the TMCC base radio signal. The key here is, either an isolated internal metal plate or strip antenna inside a plastic shell bodied engine, or the handrails or other wire structure fully isolated from the metal shell typical on steam engines forms the TMCC receiver antenna. Now here is the most important part- it measures or "receives" the difference- between earth ground wiring in your house or location and the track, thus the entire frame of the engine. Again, it's this difference in potentials that is the received TMCC signal. Again, in a crazy kind of way- think of the antenna- what it is coupling to is earth ground. It's this electrical difference in potential- the whole engine, frame, and wheels, along with the electronic receiver is connected to the output post of the base as a radio signal- and the antenna is instead coupling to effectively earth ground.

@CHARLES D posted:

Hello from England! Having intermittent problems with my track signal. Locos will stop randomly for no apparent reason in random locations often with cab light flashing. I have checked track voltage all over all OK and track is regularly cleaned. My layout is 53ft x 18ft. Reading the posts I think a DM TMCC buffer might just do the trick! I see they were developed by Gunrunner John. Are they still available? What is involved in wiring them up? Any help much appreciated!!!! Charles

I'm currently gathering contact info to get enough commitments to make another small run of them.  If you want to get on the list, send me an email to my profile email address with your contact info.  I'll let you know when we reach "critical mass" and I can do some more of these.

Hello Vernon,  this is all really helpful and it's so kind of you to take the trouble! This is all quite a lot to digest. The UK voltage and cycle certainly adds to the problem!! As does the fact I live in a large 18th century house, although it has been rewired.

Regarding methods of improvement could I run a bare copper wire out of sight underneath my Fastrack which I would connect to the house earth system??

On the other hand if I can obtain/fit the buffer presumably it wouldn't do any harm?

Thanks again! Charles

@CHARLES D posted:

Regarding methods of improvement could I run a bare copper wire out of sight underneath my Fastrack which I would connect to the house earth system??

Running the earth ground under the track is the worst possible location!  The issue is the differential between the earth ground and the track.  Putting the earth ground under the track just promotes capacitive coupling to the track and attenuates the airborne TMCC signal.

Note that you can use fine wire and it's most desirable to put it above the problem locations.

@CHARLES D posted:

Hello Vernon,  this is all really helpful and it's so kind of you to take the trouble! This is all quite a lot to digest. The UK voltage and cycle certainly adds to the problem!! As does the fact I live in a large 18th century house, although it has been rewired.

Regarding methods of improvement could I run a bare copper wire out of sight underneath my Fastrack which I would connect to the house earth system??

Edit- yes, follow @gunrunnerjohn's sound advice on specific placement and usage of additional ground plane.

On the other hand if I can obtain/fit the buffer presumably it wouldn't do any harm? Correct, I was about to make a reply we use the buffer at our local club (75feet long, by 8 feet wide for much of it, and then 12 feet in width at one end). Knowing that you are farther away, knowing import across the ocean and other complexities about availability came into play, such that if you can solve this by correcting or adding ground- that may be a good solution until you can source the buffer.

Thanks again! Charles

Hello John

As always thanks for your most helpful response much appreciated. I'm a bit of a rare breed over here; I don't know a single other modern Lionel collector here in the UK!

I intend to do all that you guys advise but would still like to purchase the buffer. Can you supply please?

Glad I can use a thin wire, it can masquerade as telephone wire!

Thanks 👍 😊 Charles

Shipping the buffer is the wild card.  OTOH, I recently shipped a similar sized box to Australia, it was easier than I imagined, but it was way more expensive that shipping it in the US.

Sorry John didn't spot your email.

I will send you an email as requested.

C

Just curious (and forgive my lack of knowledge about UK's electrical system) ...

1. When your house was rewired, was it upgraded to a grounded electrical system ?

2. Are you using the grounded three-wire plug that originally came with the TMCC base ?

3. Is the base plugged into a grounded outlet ?

4. Is it directly plugged into the outlet and not into a power strip ?

Hi John don't worry about shipping , I am used to the cost!!

Richie

Yes the UK wiring is properly earthed and 3 pin. I have a new 240v ac to 115v ac transformer 3 pin in and out. However the transformer has only one outlet socket (3 pin). So I have to use a 3 pin power strip with US 3 pin sockets, lots plugged into it. I expect that you will say I need to buy a dedicated transformer exclusively for the Legacy base??!!

Regarding the "wire ", thinking about it it would be much easier to follow the track about 3 to 4ft above it. Would a single strand bare copper uninsulated wire be ok, I would plan to have it dive down and go through the tunnels rather than above them.

How does that sound???!!!

@CHARLES D posted:

Hi John don't worry about shipping , I am used to the cost!!

Richie

Yes the UK wiring is properly earthed and 3 pin. I have a new 240v ac to 115v ac transformer 3 pin in and out. However the transformer has only one outlet socket (3 pin). So I have to use a 3 pin power strip with US 3 pin sockets, lots plugged into it. I expect that you will say I need to buy a dedicated transformer exclusively for the Legacy base??!!

No, it's just a matter of grounding. Good that your transformer has 3 in and 3 out, however that's not 100% guarantee that the 110 US style output is earth grounded. Unless you test and verify, it's just speculation.

Further, we hope that the powerstrip provides good solid earth ground, but may not.

Adding another isolation transformer to your plan- again for all we know it's not passing ground- really isn't a fix.

All you have to do is ensure the earth ground pin of the base power supply- truly is at earth ground of your UK outlet and the rest of your house wiring.

@CHARLES D posted:

Regarding the "wire ", thinking about it it would be much easier to follow the track about 3 to 4ft above it. Would a single strand bare copper uninsulated wire be ok, I would plan to have it dive down and go through the tunnels rather than above them.

How does that sound???!!!

What are your tunnels constructed of? If say it had wire mesh or screen in the construction- then the wire needs to go inside, if the tunnel is 100% non-conductive materials (plaster, paper, plastic, wood) then a wire overhead is fine.

@CHARLES D posted:

Yes the UK wiring is properly earthed and 3 pin.

I have a new 240v ac to 115v ac transformer 3 pin in and out. However the transformer has only one outlet socket (3 pin).

So I have to use a 3 pin power strip with US 3 pin sockets, lots plugged into it. Problem is, we are assuming it's grounded because it's all 3 pin and should be grounded. Unless you test and validate that earth ground, we just don't know.

I expect that you will say I need to buy a dedicated transformer exclusively for the Legacy base??!! No, most definitely NOT.

Again, just to be clear, the power situation and a single AC drop down transformer  and then into a power strip is probably the safest and perfectly fine. As I've said in other topics- the instant you have more than one transformer- phasing becomes a big deal. Imagine this at line current- it's a whole different ballgame.

FWIW, I lived in Europe from 1995 until 2003, and used my fair share of drop down transformers for US equipment, and even in the UK. I've seen plenty that simply were not grounded, and I've seen the out of phase thing between two or more of them.

You just need to know- again, the only thing that does need 100% earth ground, is the small power supply for the legacy base- specifically the round 3rd pin.

Hello Vernon that's all really useful and I will get on with what you suggest, thanks so much.

Incidentally my wife spent 26 years in the US Air Force and when she was based in the UK the whole house was festooned with transformers and wires to run all her US appliances I'm sure that they were a fire hazard!!!

@CHARLES D posted:

Regarding the "wire ", thinking about it it would be much easier to follow the track about 3 to 4ft above it. Would a single strand bare copper uninsulated wire be ok, I would plan to have it dive down and go through the tunnels rather than above them.

How does that sound???!!!

Truthfully, I use insulated wire as I do NOT want it ever touching anything that might be common to the outside rails, that's the kiss of death for the Legacy track signal.   For my first level that goes under the second level, I had a few issues with certain engines, I just ran some #30 insulated wire around under the deck of the second level, it was a perfect position to solve the signal issue on the track below.

Hello again, I am so grateful for all the help and advise with this, you have no idea how much this is appreciated.

My final question!!

I have checked the earth at the mains supply in on the layout and it tests 100% good. So I was going to run a wire round and above the layout and connect one end into the earth pin of a plug and plug that in to the 3 pin outlet on the layout supply.

Being a farmer I thought electric fencing wire would be ideal as it has  interwoven metal strands  and is thin so it can be stretched tightly which makes a neater job.

I would prefer it out of the way so around three feet above the track would be ideal, is that OK please?

Thanks Charles

@CHARLES D posted:

Hello again, I am so grateful for all the help and advise with this, you have no idea how much this is appreciated.

My final question!!

I have checked the earth at the mains supply in on the layout and it tests 100% good. So I was going to run a wire round and above the layout and connect one end into the earth pin of a plug and plug that in to the 3 pin outlet on the layout supply.

Being a farmer I thought electric fencing wire would be ideal as it has  interwoven metal strands  and is thin so it can be stretched tightly which makes a neater job.

I would prefer it out of the way so around three feet above the track would be ideal, is that OK please?

Thanks Charles

3 feet above the track is great, on the ceiling would be fine if this is the upper track (assuming multi-levels).