Hi guys, great conversation going here, keep it up. I'd like to see this topic end up being THE PLACE to come do discuss everything related to the 455Khz signal. That's why I'll be transitioning the title to better reflect what the conversation is all about.

My layout is an interesting testing ground with plenty of quirks and mysteries to solve. There are lots of theories out there on how to make our trains run better, and with any luck we can prove or disprove many of them in this thread.

I am not a "scientist". I do not have the electronic background or education that some of you have. What I do have is a general understanding of many of the concepts, which I have picked up from many of you over the last few years. I also have a willingness to learn and try new ideas based on your suggestions.

I had a wonderful phone conversation with Dale last night. We talked about more tests that should be done as well as my grand layout control scheme and how it was all going to tie together with C/MRI, JMRI and TMCC/Legacy to create a fully automated CTC mainline. The theory for all of it is quite sound, as most of those components have been around for a long time, and are well tested. The secret to reaching the end goal is perfecting the track signal for smooth, RELIABLE operation.

Sorry I got a little behind in replying to your responses this morning, there were so many, I got a little overwhelmed.

Dale, the radio should be here next week so I can do the sweep (and check some locos). I have to reconnect the bases and track power, in order to do the chicken wire disconnect test.

Chuck, maybe we should try to rename the term "ground plane" to something like "earth ground carrier". It would be more accurate and descriptive.

BobbyD, Nick is right, another Legacy base would not have been the answer for this problem. All that would have said was one base worked and the other didn't. This was all about probing the bad base to figure out what made it bad. The fact that it was intermittently bad, made it confusing on one level, but also made it possible to ultimately pin down the problem.

Interesting. so without  purchasing an oscilloscope, is there a simple way to check the strength of TMCC / Legacy signal on your layout. What areas on the layout would you test?

J Daddy posted:

Interesting. so without  purchasing an oscilloscope, is there a simple way to check the strength of TMCC / Legacy signal on your layout. What areas on the layout would you test?

Yeah, John, so far there hasn't really been much talk of a scope. Dale's meter seems like it will do all the tasks necessary for now, including probing suspect areas of the track for comparative values. The cheap AM radio is to sniff around for 455Khz noise emitters. That level of sophistication I can deal with.

Big_Boy_4005 posted:

Chuck, maybe we should try to rename the term "ground plane" to something like "earth ground carrier". It would be more accurate and descriptive.

I kind of like "ground wire antenna"...

But it'll never happen. Ground plane is so catchy .

First post repair test: PASS

I reconnected both bases and plugged in the power supplies. All engines stayed at rest. No more "Runaway Train" or "Unstoppable" (both bad movies ). Cab-1's work as expected.

cjack posted:

Big_Boy_4005 posted:

Chuck, maybe we should try to rename the term "ground plane" to something like "earth ground carrier". It would be more accurate and descriptive.

I kind of like "ground wire antenna"...

But it'll never happen. Ground plane is so catchy .

It is rather confusing, isn't it.  With the TMCC signal the true 'ground plane' as the term is used in other radio applications, is the track with it's U post half of the signal.  Then we are using 'Earth ground' to broadcast the other half of the signal.  Very backwards from how folks brains want to think of things. 

JGL

Dale suggested renaming it a while back. I think it was suggested to be name ground signal radiator or something like that.

Here is that thread.  As you can read I was initially opposed to changing the term due to the widely recognized but incorrect term "ground plane" was instilled into the TMCC culture but today I try to use the term "ground signal radiator" and explain why.  I think Dale's initial thought was probably something we all should have started using a while ago.  Dale has done more for TMCC / Legacy signal understanding than anyone I know.  We could call it the "Dale Effect"  LOL!

Dale, the radio should be here next week so I can do the sweep (and check some locos). I have to reconnect the bases and track power, in order to do the chicken wire disconnect test.

Big Boy 4005

Can you please explain what the use of the radio is for, I guess I missed something. Thank you

Ray

Ray, the 455Khz track signal frequency is just below the regular AM dial. Dale feels that it is close enough when tuned to the low end ~530Khz, that it can detect potential interference emitters around the train room. As we were discussing this in our phone conversation, Dale had an Ah Ha moment. It relates to what Mike Reagan said in this topic 3 1/2 years ago regarding the unshielded coil on the Railsounds board. What Dale realized was, the radio could probably detect that "noise" too. This way you shouldn't have to open up the engine to find out if it's a problem.

Lionel added shields to updated boards, but the boards are $40. For about 10¢ in materials, you can make the shield yourself (labor extra of course).

Elliot, you can also find old dead RS power supply boards with the shields and retrofit them.  They fit on the old boards with the exposed coil.

John, I'm not even sure where to look for old dead boards, I live in a 3 rail wasteland. I think it's easier to make them now that I have the pattern. Dumpster diving behind the hobby store isn't really my idea of a good time.

Where's your sense of adventure?

gunrunnerjohn posted:

Elliot, you can also find old dead RS power supply boards with the shields and retrofit them.  They fit on the old boards with the exposed coil.

My thought...I know where there is one

Update:

I've done a couple of things on the layout since we last talked. I installed a ground plane wire on top of that superstructure that I built. Unfortunately, the results were not what I had hoped or expected. There was no real change in engine performance, though a couple odd things happened during the test. Random engines on different areas of the layout woke up with their sound on. They didn't move, but they were revving at high RPM's. When I went address them with the Cab-1, and shut them up, they would not obey. On one occasion, I tipped the engine to lift the rollers off the center rail, and let it back down. That cleared the sound before I had to resort to ear plugs or aspirin.

I also did Dale's chicken wire disconnect test.  I unplugged the layout lighting which tied the chicken wire to earth ground. Then using Dale's meter, I measured the signal level going to the layout. Remember that the Legacy base measures about 2000 when the layout is NOT connected. With the layout connected, and the lighting unplugged, the meter read 1000. I did a quick continuity test between the chicken wire and a different piece of conduit which was still connected to earth ground. Results negative, no connection. The chicken wire was isolated.

So the layout itself is dropping the signal by half. Then I plugged the lighting back in, and the signal dropped to 950. After that, I turned the lights on and the signal dropped to 920.

I guess the next step is to start using the meter to take readings around the layout, and measure the signal level at the bad spots. How low will it go?

You might be interested in some test results from checking the output of the Legacy base with various levels of capacitive loading.  It may explain some of your results.

 Check the PDF file attached to this post.  When reading, note the voltage scale changes as the capacitance gets larger, so you need to factory that into your reading.  When we get to .1uf, the signal is only about 300mv, probably way too little to function properly.

I see that at .1μ, the wave is very noticeably crushed. I'm assuming that if I had a scope, and knew how to read it, I would see this effect in the bad spots.

Hard to say, but I suspect you'd see a weak signal.  All you need is a 'scope.

gunrunnerjohn posted:

Correct Dale, my point was simply that it was a DC measurement when you look at it.  Their sample application does have the resistor and cap.

Earlier you said:

I recall them saying when the signal was in the 40's, everything was great.  When the signal dropped down past about 30 and lower, the wheels started to fall off. 

What are the units?

The 455 kHz IC receiver meter output is a current proportional to signal strength with a specified nominal uA per dB slope.  The 51k resistor converts the units to Volts per dB.  The 0.1uF capacitor smooths the voltage.  For average signal strength you want to set the meter to DC Volts.   It's puzzling that the photo shows the meter set to AC Volts?

gunrunnerjohn posted:

You might be interested in some test results from checking the output of the Legacy base with various levels of capacitive loading.  It may explain some of your results.

 Check the PDF file attached to this post.  When reading, note the voltage scale changes as the capacitance gets larger, so you need to factory that into your reading.  When we get to .1uf, the signal is only about 300mv, probably way too little to function properly.

So, John,

He has one outside rail for his train detection circuit with isolated blocks. Each isolated block outside rail block break is joined with a .1uf capacitor according to Mike Reagan's video for creating a capacitive coupling to allow the signal to travel that rail.

According to the charts, it appears that value kills the signal.

It looks like it should be a .01uf

Yes, No ?

Edit: photo from earlier reply

Looks like 1042 caps or 1uf

Where are we now? does TMCC  still work?  Has  Carl's post above found   part of the problem?  re the   . 1uf or .01 uf?  .

If you're trying to coupler the TMCC signal, the .1 would be correct IMO.  Capacitive reactance of a .1uf cap at 455khz is around 3.5 ohms, and of a .01uf cap at 455khz it's around 35 ohms.  Since at 60hz it's over 26kohms, I like the .1 to couple the signal.

stan2004 posted:

gunrunnerjohn posted:

Correct Dale, my point was simply that it was a DC measurement when you look at it.  Their sample application does have the resistor and cap.

Earlier you said:

I recall them saying when the signal was in the 40's, everything was great.  When the signal dropped down past about 30 and lower, the wheels started to fall off. 

What are the units?

The 455 kHz IC receiver meter output is a current proportional to signal strength with a specified nominal uA per dB slope.  The 51k resistor converts the units to Volts per dB.  The 0.1uF capacitor smooths the voltage.  For average signal strength you want to set the meter to DC Volts.   It's puzzling that the photo shows the meter set to AC Volts?

I know Stan, clearly the meter wasn't set right, that's all I can figure.  The NJ-HR guys are the ones to ask.

gunrunnerjohn posted:

If you're trying to coupler the TMCC signal, the .1 would be correct IMO.  Capacitive reactance of a .1uf cap at 455khz is around 3.5 ohms, and of a .01uf cap at 455khz it's around 35 ohms.  Since at 60hz it's over 26kohms, I like the .1 to couple the signal.

Well, it looks like he has 1uf, no decimal points, unless I found a different 1042. What does that do to the signal?

oops! 104 Z   .1uf  sorry, didn't zoon enough     Thank you , John.

But, that rail needs a cap from the legacy base wire in series to the outside isolated rail or it gets no signal.

gunrunnerjohn posted:

If you're trying to coupler the TMCC signal, the .1 would be correct IMO.  Capacitive reactance of a .1uf cap at 455khz is around 3.5 ohms, and of a .01uf cap at 455khz it's around 35 ohms.  Since at 60hz it's over 26kohms, I like the .1 to couple the signal.

This subject came up in my phone conversation with Dale. The upshot was that the .1μ caps were almost useless, since the train actually grounds both rails as it passes. The train sort of brings the signal with it as it hits the insulated rail.

We were also both skeptical track "halo effect" where the train moves through a "tunnel" of signal. I would love it if we could prove or disprove these TMCC legends here.

Gregg the bases are hooked up, I can run trains. Not as well as I would like, but that's what we are working on here. This will probably go on for quite a while, unless we stumble onto a miracle. If and when we do, you'll know.

Carl, it's a lot easier to read the label from the bag they came in, than it is to read the component in a photo. Trust me, they're .1μ.

 Thanks for the update...  great thread.

gunrunnerjohn posted:

Hard to say, but I suspect you'd see a weak signal.  All you need is a 'scope.

If I buy one, I'll have YOU teach me to use it. Actually, you'll have to teach me what to buy first.

Gregg posted:

 Thanks for the update...  great thread.

You're welcome. We'll try to keep this fun, interesting and informative in the process.

Elliot, you never know when a miracle is just around the corner, keep the faith.

gunrunnerjohn posted:

Elliot, you never know when a miracle is just around the corner, keep the faith.

Gee John, maybe buying a scope isn't so far fetched after all. It's just a tool, and dealing with all this signal stuff and the C/MRI it could be very useful. The last time I used one was high school physics. It might even help me understand electronics better, and that certainly couldn't hurt.

As for keeping the faith, I am. Even when others around here have "lost it".

I'll go back to my seat now.

Elliot, the digital 'scopes are very cheap nowadays, I remember the days when I would have given my left nut to be able to afford one, now they're less than a Legacy diesel.

Yeah John, I just looked on Wikipedia and saw some pictures of some newer models. I had no idea what was out there. My mind is stuck in a time warp, I thought they were still big clunky boxes. Less than a Legacy diesel, huh. OK, you've heard my two major projects, I'm sure there will be other smaller ones along the way. What do you recommend?

Sorry Carl, I wasn't trying to be mean. I do make mistakes like everyone else. It's good to have as many eyes on things as possible to make sure I'm not missing anything. This is very technical stuff, and John, Dale and some of the others keep bringing up new concepts and theories to consider. I don't get all of it, but I'm trying.

gunrunnerjohn posted:

Elliot, the digital 'scopes are very cheap nowadays, I remember the days when I would have given my left nut to be able to afford one, now they're less than a Legacy diesel.

One of my favorites...Rigol DS1102E

http://www.tequipment.net/Rigo....html?b=y&v=7906

gunrunnerjohn posted:

 

I know Stan, clearly the meter wasn't set right, that's all I can figure.

So has anyone actually mapped/plotted the signal-strength around their layout using meter output signal from R2LC pin-13?   I'm not talking about measuring the 455 kHz strength on the track but the 455 kHz as received via the antenna.  I'm thinking of something like the cellphone coverage maps from AT&T, Verizon, etc.. 

I'd think having a real-time indicator of received signal strength with meaningful resolution (2.1 vs. 2.2 vs. 2.3 etc.) would be invaluable.  You could make adjustments or changes to grounding, capacitance, whatever, and watch the received signal strength change in a way that you'd know if you're getting warmer or colder so to speak.  The pin-13 dynamic range is enormous (60 dB or 1000-to-1) with resolution to see changes of a few percent one way or the other - as opposed to go/no-go observations of whether TMCC commands are making it through.

The pin-13 method has been brought up for years in different threads.  Has it been dis-credited or shown ineffective?

cjack posted:

gunrunnerjohn posted:

Elliot, the digital 'scopes are very cheap nowadays, I remember the days when I would have given my left nut to be able to afford one, now they're less than a Legacy diesel.

One of my favorites...Rigol DS1102E

http://www.tequipment.net/Rigo....html?b=y&v=7906

I really like the sound of that unit. The price is very doable too. Now all I need is to learn how to use it. Unfortunately, it's slightly more complicated than a hammer.

stan2004 posted:

gunrunnerjohn posted:

 

I know Stan, clearly the meter wasn't set right, that's all I can figure.

So has anyone actually mapped/plotted the signal-strength around their layout using meter output signal from R2LC pin-13?   I'm not talking about measuring the 455 kHz strength on the track but the 455 kHz as received via the antenna.  I'm thinking of something like the cellphone coverage maps from AT&T, Verizon, etc.. 

I'd think having a real-time indicator of received signal strength with meaningful resolution (2.1 vs. 2.2 vs. 2.3 etc.) would be invaluable.  You could make adjustments or changes to grounding, capacitance, whatever, and watch the received signal strength change in a way that you'd know if you're getting warmer or colder so to speak.  The pin-13 dynamic range is enormous (60 dB or 1000-to-1) with resolution to see changes of a few percent one way or the other - as opposed to go/no-go observations of whether TMCC commands are making it through.

The pin-13 method has been brought up for years in different threads.  Has it been dis-credited or shown ineffective?

I can just hear the little engineers asking, "Can you hear me now?" Seriously, a layout signal level map would be very cool.

Interesting to read but this is like learning Japanese for me I.e. It's way over my learning curve.

To bad there wasn't a "booster" you could hook up to amplify the signal. Again how do the NJ High-Railers do the same on a monster layout without signal loss?

I picked up a really cheap scope a few years ago. I had not used one since college. I bought it to look at the sine wave from my pure sine inverter. In other words to check 60Hz was being produced correctly. 

It's pretty basic, cost under £100 when I picked it up.I have not tried looking at the Legacy/TMCC signal with it though. 

Needs GRJ, Chuck or one of the other knowledgable chaps to check the specification to see if it will do the job.

It's very portable which might be handy.

http://www.maplin.co.uk/p/vell...t-oscilloscope-n55jn

Nick

Nick, while that 'scope would probably suffice, I'm a fan of buying a tool that will not limit you in the future.  Here's the Rigol DS1102E on eBay: 252273188974 for $350 shipped.  It's a new unit in the US that has been opened but not unpacked.

Stan, I like the idea of using the R2LC output and actually trying to map what you have.  What would be really slick is to have the value read be broadcast to a remote receiver so you could take readings where you can't see the unit.  Failing that, perhaps a "smart" unit that would give you varying tones based on signal strength so you could get readings where you can't really see a meter.

I recently bought one of the 100 MHz digital scopes for around $280.  I love it.  It is much smaller and lighter than my other 'scopes, and much 'smarter'.  One of the other Forum members recommended it to me.

A number of different vendors sell what is essentially the same 'scope.  Mine is the Hantek DSO 5102P.

I wish I could hook up a 12V gelcell and make it portable.

John, your Rigol looks the same as my Hantek, but costs $100 more!

Looks almost identical in function and specifications to mine, but mine is the ATTEN ADS 1102CAL, I'm guessing all of these guys share the same guts.  I've seen posts where people take the Rigol firmware and load it into the model I have, clearly they're very close.  I prefer to just use it as it came, it works fine.

I think I may need to upgrade my equipment...

To be honest, I haven't used a scope in several years now, but I used the heck out of these two while growing up.  they still work just fine, or did the last time they were used.  The pics are from the net, as mine are packed away right now.  

JGL

My first one...

JohnGaltLine posted:

I think I may need to upgrade my equipment...

You ain't kidding!

Well guys, while it would be really cool to have a scope, I worry that it would be a case of "pearls before swine". I can buy it. I could hook it up. I could get a picture, but I wouldn't know what it means. I want it to be a tool and not a toy. Without some serious education, I'm afraid that is all it would be.

I guess the $64,000 question is, what useful information could be gathered for this project, that only a scope could ascertain? Is it just something that would be nice to know, or will it really allow us to pinpoint some actual issues with the signal?

I suppose, I always have you guys to help interpret the test results, if I get it. I would need you to tell me what tests to run and what we were looking for. I'm game for that if you are. I would certainly learn as we go, so there is that. Before I spend the money, I just want to be sure that it's the right decision.

Thanks!

I'd hold off for a spell.  While it would probably be useful to have one, I do question if you'd get your money's worth from it.  I principally use mine on the bench for development work. 

I think a better investment might be the track signal engine with a remote readout or audio tone to do some signal strength mapping.

gunrunnerjohn posted:

I'd hold off for a spell.  While it would probably be useful to have one, I do question if you'd get your money's worth from it.  I principally use mine on the bench for development work. 

I think a better investment might be the track signal engine with a remote readout or audio tone to do some signal strength mapping.

Thank you John! This has been a fun and interesting side discussion, but it is good to see that we've come to our senses.

Let me go find my donor R2LC. A few years back, I had an early TMCC engine split a switch and fried the insulation on the internal wiring. I hope that board is still good, but I think it is. Did I see that project needed a 51K resistor and a .1μ cap? I can't remember, resistors in series you add? if so, I can make 51K or very close from what I have on hand. The cap, I have a drawer full. Times like this when you miss Radio Shack, though my luck they wouldn't have had it anyway.

Thinking along the lines of a test engine. I wonder if that little scope I have could be used onboard?

Now I have not used it very much so I'd have to read through the manual. But I remember it has a record function. It might be able to work as a onboard data logger. So could you produce a signal map for a particular track route from the data?? 

Nick

GRJ,

Thinking about options to send data from a moving engine to remote location.  Am I understanding correctly that the "data" is a DC voltage from the R2LC board?  What is the range of voltages here?  As is often the case I'm thinking an Arduino could be used with one of it's A to D pins, then it could forward that data over a wireless module to another Arduino.  The basic example for the nRF24 library does just this without any, or much modification needed.  

JGL

John, that's exactly what I was thinking.  The voltage is from 0 to 5V, a good match for the A/D.  Something like the Arduino Nano A/D could capture the value and send it over a wireless link.  I haven't looked at the exact software, but I suspect a similar library would be useful.  I found this when I searched...

This NRF24 library has now been superceded by the RadioHead library http://www.airspayce.com/mikem/arduino/RadioHead RadioHead and its RH_NRF24 driver provides all the features supported by NRF24, and much more besides, including Reliable Datagrams, Addressing, Routing and Meshes. All the platforms that NRF24 supported are also supported by RadioHead.

I guess that would be the one to look at.

Big_Boy_4005 posted:

Did I see that project needed a 51K resistor and a .1μ cap? I can't remember, resistors in series you add?

Correct - 51k and 0.1uF.  Anything near 51K will work just fine.  You might have 47k for example.  Just make a note of what you used when reporting results. 

Yes, resistors in series add.  Or, equal resistors in parallel divide by 2 - you may have 2 100k resistors which in parallel would make a 50k resistor.

I'm curious to see what GRJ and JGL come up with for a wireless gadget...but in the meantime for 10 cents in components and some careful soldering, you can make a signal-strength tool.   I say 10 cents because the multi-meter shown earlier is a Harbor Freight "freebie" meter which works fine for this application.  I saw a Harbor Freight free-with-coupon in today's Sunday paper for this exact meter...and snooping on your zip code I see there's a Harbor Freight nearby!  It comes WITH battery and for that price you can snip the meter leads to make them shorter and maybe drag it around on a flat-car.

Thanks Stan, I have plenty of 47K's and 2200's. What's 400Ω between friends at that level? As for the meter, got that exact unit.

The idea of dragging the meter unit around the layout is great. However, under normal circumstances, with the signal problems we are trying to map, that's not as easy as it sounds. LC+ to the rescue!!!

STAN2004

Hi, Could you post a Picture of  Meter what your talking about in Harbor Freight ?

kb2agpjohn@aol.com  If you like send it my E-mail. 

I have Harbor  Freight Right around the Corner. 

Thanks, John

An idea just popped into my head. It might be something, it might be nothing, probably nothing.

What part of the radio spectrum is used for wireless alarm communication?

About 2 years ago we switched providers, and they took us wireless. That may be when the trouble started, or it could just be my imagination working overtime.

NYC,SUBWAY TRANSIT SIGNAL posted:

STAN2004

Hi, Could you post a Picture of  Meter what your talking about in Harbor Freight ?

kb2agpjohn@aol.com  If you like send it my E-mail. 

I have Harbor  Freight Right around the Corner. 

Thanks, John

John, it's the one sitting in the UP Alco posted and reposted on the previous page. It's a little red meter.

Wireless alarms would be up in the gigahertz frequencies. 2.6 to maybe 6.0 Gigahertz. It could interfere with your CAB2 to base. But not with your base to track for that frequency is about .000455 gigahertz.

NYC,SUBWAY TRANSIT SIGNAL posted:

 

Hi, Could you post a Picture of  Meter what your talking about in Harbor Freight ?

10/4 Head over there tomorrow.

Ya,We stop getting Sunday Paper a long time ago.

Thanks again, John

I'm on their e-mail list too.

cjack posted:

Wireless alarms would be up in the gigahertz frequencies. 2.6 to maybe 6.0 Gigahertz. It could interfere with your CAB2 to base. But not with your base to track for that frequency is about .000455 gigahertz.

Thanks Chuck, guess we can rule that out. I haven't used the Cab-2 yet, I'll get to that later.

I just got a chance to watch GLA 11, and Bob Bartizek was saying he only uses TMCC and not Legacy, partly because the Cab-2 didn't have the range he needed, but mainly for operations, he didn't need the "fluff". I concur, but I bought with one engine in mind, my Milwaukee road S-3. I'll reach for the Cab-2 when that baby finally hits the rails.

Actually, wireless alarms are in the 300-400mhz range, still way outside what you're looking at.  I think my GE Concord 4 wireless is 319.5mhz for it's wireless sensors.

Like garage door openers then. Wonder how they decide where to put the frequency...FCC rules?

Big_Boy_4005 posted:

I have plenty of 47K's and 2200's. What's 400Ω between friends at that level?

It's up to you, but using just a single 47k (since you have it) will give you just as much information as trying to get it closer to 51k.  Just keep a note that that's the value used and you're good to go.  After all, 400 ohms is about 1% of 51k and I'm guessing you don't have a stock of anything better than 1% resistors anyway! 

Big_Boy_4005 posted:

 

An idea just popped into my head. It might be something, it might be nothing, probably nothing.

What part of the radio spectrum is used for wireless alarm communication?

Earlier I think you said you were getting an old-school AM radio to sniff around the layout.  Note that with R2LC meter output you are building a sniffer for signals around 455 kHz.  So in practice what you should do is run the train with meter around the layout with the TMCC base turned OFF to get a background/baseline reading.  The meter will NOT read 0 and will probably vary around the track.  Be suspicious of areas where the readings are consistently higher - are there electrical/electronic accessories nearby? 

The point is the AM radio and the R2LC meter measures any energy at the selected frequency.  It does not tell you if it is useful energy.  Stated technically, you are measuring the sum of the signal (desired) plus noise (undesired).  By measuring around the layout with the TMCC base turned OFF you get a proxy for the noise level.   In terms of reliable data transmission, you want a high ratio of signal relative to noise....or what's commonly referred to as signal-to-noise (S/N) ratio.  So when you get a high reading at some location on the track you need to be sure this from desired (TMCC transmitter) signal level and not from the noise level; that's why it's important to first run a test of the noise level with the TMCC base turned OFF.  As you astutely point out, LC+ to the rescue!

cjack posted:

Like garage door openers then. Wonder how they decide where to put the frequency...FCC rules?

As a note, my alarm uses the 2.4GHz band.  

As to how the various frequency ranges are chosen, it tends to actually be a LACK of FCC rules.  The bands that are used for consumer devices are popular for these devices because manufacturers are free to use them with out needing a license.  You can thank your microwave oven for your Wifi and bluetooth and everything else on the 2.4GHz band.  The magnetron inside a microwave radiates noise at 2.4GHz, and because of this, the FCC determined it was a garbage band that was not of any use for  anything that needs to be regulated.  Amazing what can happen when you free just 500 megahertz of air space from regulation.  

Other bands have similar stories where the area was determined to be of no use to anyone, so left unregulated.  The old stand-by of 27MHz was popular for R/C control as well, with six dedicated rc channels mixed between the 40 CB radio channels that occupy the same area.  This was most likely left open for public use as it falls just below the world standard 10 meter amateur radio band.  I know for a fact every 27MHz device in the house is useless when My mother would fire up the Ham radio at 10 meters.  Also drove the neighbors nuts.  

You can see the entire regulated spectrum here:  https://transition.fcc.gov/oet...m/table/fcctable.pdf  It's not actually very useful for the average person, but fun to look through to see all the stuff going through the air around you.  

JGL

The commercial alarms tend to use the 300-400mhz frequencies, when I was looking for mine, they had some consumer models in the 2.4ghz band, but most of the commercial models are on lower frequencies.  Here's an interesting article on jamming wireless systems, it lists a bunch of the frequencies: http://ipvm.com/reports/hack-adt-alarm-system

Nice, Do you have a layout diagram? How big will the curves be? etc.

for railroad testing , is it possible to just turn the house security alarm "off" ?

Gregg, there really is not a way to turn the alarm off, but given what everyone has said, the operating frequency is not in the range that will bother the layout.

George, I have been trying to redraw the track plan into its final configuration. The upper deck plan is sitting on my drafting table about 70% complete. The lower deck redraw hasn't been started, but the original plan is fairly accurate. There are no curves on the mainline under 072, and most are wider. There are no curves less than 054 anywhere. This really doesn't have anything to do with the signal issues, except that it would be nice to have a paper copy to map the test results.

Stan, I'm going to gather all the components to make the meter car, then I can do a step by step assembly here with photos, in case anyone else wants to build one. I will probably need a little coaching to make the right connections. Thanks, that bit about LC+ just popped into my head. I do have my moments once in a while. Fortunately, they're not all "senior" (yet).

stan2004 posted:

gunrunnerjohn posted:

Correct Dale, my point was simply that it was a DC measurement when you look at it.  Their sample application does have the resistor and cap.

Earlier you said:

I recall them saying when the signal was in the 40's, everything was great.  When the signal dropped down past about 30 and lower, the wheels started to fall off. 

What are the units?

The 455 kHz IC receiver meter output is a current proportional to signal strength with a specified nominal uA per dB slope.  The 51k resistor converts the units to Volts per dB.  The 0.1uF capacitor smooths the voltage.  For average signal strength you want to set the meter to DC Volts.   It's puzzling that the photo shows the meter set to AC Volts?

 

Hi Guys

Been off from the forum for a week and just picked just up this thread on TMCC/Legacy signal and saw the picture of the earth ground signal test car which I built at the NJ-Hi Railers.  When taking earth ground signal readings you need to be on u amp setting.   When I originally took the picture, I didn't pick up the meter was set for ac volts.   This test car has been a "EXTREMELY USFULL" tool in addressing the TMCC/Legacy signal issues we had on our 30' X 200' layout, as it will indicate where you have week earth ground signal.  Also, when you attempt making changes to improve signal strength, you know right away if what you are doing has helped or not.  I would recommend anyone who is having serious earth signal issues (when you put your hand over the engine, your engine head light goes from nothing/blinking light to a solid on light)  to build one of these earth ground signal test cars which consists of a radio board, resistor & a capacitor.    I posted once before the forum complete plains of making one of these, and if anyone wants I can repost it.  

The other important item, is testing the other part of the TMCC/Legacy signal which comes from the "U" terminal of the command module.  Here we used as mentioned above, an oscilloscope to test signal strength and visually see if the signal was being corrupted by the layout.

Bob D

NJ-Hi Railers

Bob, by all means, please post your instructions.

Bob, welcome to the conversation. That would be great if you would repost that here. I'm 99% sure I saw it and marked it, but it might take some digging, as I read and mark all topics related to TMCC signal here on the forum, and even some off. I was just gathering the materials for it now. The last piece missing is the car itself. I suspect I will be choosing a lighted caboose as my victim to donate its chassis to the cause.

At first I thought that the R2LC was going to come out of an early TMCC Dash 8, but when I opened it up, it was the old style electronics which predate the plug in boards. One thing caught my eye when I was in there, that was the antenna. New engines have their antennae just below the top of the shell in the form of a plate or a foil strip actually stuck to the plastic.

This unit had its wrapped around the inside of the nose of the cab, much lower than what we see today. The reason I bring this up is, of all my engines, I only have a few of these early units. I don't like the pulmor motors and the chunky bodies. However, one such unit seems to be immune to these signal issues. This can be seen in a couple of GoPro videos shot on my layout. Could the antenna placement be part of the secret to its success?

I'd be interested in the plans too.  While I have not experienced signal issues with Legacy ( knock on wood ) so far, that's not to say I'm in the clear yet.

Regarding the use of a portable radio for detection.  I hear the noise that Legacy produces over my stereo tuner in the layout room.  Is the detection procedure thus... a) shut down Legacy and scan the room with the portable, listening for any RFI set up by appliances, lighting, etc.?  and b) turn on Legacy and scan all areas with the portable, listening to the RFI set up by Legacy to see if it lessens in poor signal areas?

Bruce

Question: What is your Electric Bill every Month ?

I hope you guys  are using Energy saving Light Bulbs.

Please don't forget about Signals for beautiful Layout too.

Integrated Signals Systems.com 

Good luck, John 

Bob, I would think that you would either use the 51K resistor to turn the current into a voltage that is read with DC volts, OR

Use only the capacitor and read the current directly with the meter set to microamps,

But not both resistor and current measurement.

Perhaps the meter's low resistance in the current measurement mode just swamps out the effect of the 51K resistor (which is in parallel with the meter), hogging almost all the current.

In the chip's data sheet there is a designation near the RSSI meter that is 100KV, which might have been an attempt to say that the RSSI meter movement should be a 100K ohm/Volt meter - more properly written 100K/V.  A 100K/V meter that is 5V full scale would be a 50 uA movement.

None of this is critical for us if we just chose a circuit configuration and all use it.  I suggest the 51K, .1 cap and the meter set to 2V DC.  My gut feel is that we aren't going to get anything stronger than 2 volts for our whimpy pickup antenna. 

(An improvement might be to use a ferrite-rod "loopstick" connected between the antenna input and ground to get a better signal, but this would also introduce a lot of directionality to the signal pickup, which might be different than the antenna plate of a diesel or the handrails of a steamer.)

FWIW, I used a 9V battery to power my R2LC.  That way I just need to run a ground wire to the trucks - no rollers required.  I just realized that I also used one of the 2411 PW metal flatcars, which might have a different characteristic than a plastic gondola.  I did take care to rigidly mount the antenna, which is a chunk of brass rod.

I did a search and found the following post with what I believe are the aforementioned notes.

https://ogrforum.ogaugerr.com/t...48#48874849343058248

I took the liberty of copying the key diagram:

I agree with Dale's comment about using the meter's Current measurement mode.   The Harbor Freight meter probably uses a 1k Ohm burden resistor for the 200uA range.  So as Dale says, this swamps out the 51k resistor and you are left with a 1k Ohm load and a voltmeter.  In any event this answers my earlier question of the scale when below 30 is bad, above 40 is good.  The meter could have been in the Voltage measurement mode without the 1k resistor swamping out the 51k resistor. 

The technical considerations get somewhat bogged down with the filtering effect of the 0.1uF capacitor when there's a 1k vs. 51k Ohm parallel resistor and how this plays off with the integrating algorithm of most hobby-grade voltmeters.

Bottom line is to simply make note of what measurement setup you're using so numbers from different set-ups can be normalized/compared.  I believe that if/when GRJ or JGL implement their wireless transponding signal-strength system, it will measure voltage (not current) as that's what the Arduino can do directly.

Bruce, basically just step a).  We are sniffing for noisy lights, switching power supplies, or leaking/arcing capacitors on the AC line inputs to most electronic devices.

I once had an AM noise problem (not with TMCC/Legacy, but just my AM radio) that was due to arcing contacts on a neighbor's aquarium heater.  The noise would cycle on and off as the heater turned on and off.  (We share the same power transformer.)

A somewhat related problem is desensitizing.  If there is a strong unwanted signal that gets into the front end of a radio receiver, that signal can activate the Automatic Gain Control circuitry that normally avoids overload with loud (desirable) signals.  In this case, the gain is also turned down for our wanted signal, desensitizing the receiver.  The R2LC has a tuned input stage that narrows the reception band to keep out unwanted signals, and there is no AGC.

Dale Manquen posted:

Bob, I would think that you would either use the 51K resistor to turn the current into a voltage that is read with DC volts, OR

Use only the capacitor and read the current directly with the meter set to microamps,

But not both resistor and current measurement.

Perhaps the meter's low resistance in the current measurement mode just swamps out the effect of the 51K resistor (which is in parallel with the meter), hogging almost all the current.

In the chip's data sheet there is a designation near the RSSI meter that is 100KV, which might have been an attempt to say that the RSSI meter movement should be a 100K ohm/Volt meter - more properly written 100K/V.  A 100K/V meter that is 5V full scale would be a 50 uA movement.

None of this is critical for us if we just chose a circuit configuration and all use it.  I suggest the 51K, .1 cap and the meter set to 2V DC.  My gut feel is that we aren't going to get anything stronger than 2 volts for our whimpy pickup antenna. 

(An improvement might be to use a ferrite-rod "loopstick" connected between the antenna input and ground to get a better signal, but this would also introduce a lot of directionality to the signal pickup, which might be different than the antenna plate of a diesel or the handrails of a steamer.)

FWIW, I used a 9V battery to power my R2LC.  That way I just need to run a ground wire to the trucks - no rollers required.  I just realized that I also used one of the 2411 PW metal flatcars, which might have a different characteristic than a plastic gondola.  I did take care to rigidly mount the antenna, which is a chunk of brass rod.

Dale

I am sure there are several ways this can be implemented.  I just followed what the specs indicated for the MC3372 IC, to get a RSSI output, using a 51K resistor & .1u cap.  It gave us at the club what we needed, which was a way to measure signal strength as we tried different ways to improve the earth ground portion of the signal and get real time results.

Also, this all originally came from a post that Gary Emmich posted over a year ago on how to get signal reading off of the Lionel radio board, which I took the info and made up the signal car.  

 I can't find my original write up, so putting the pieces together again as we speak and I will sent out a post shortly with all the information I have on the signal car.

Bob D

I'd probably opt for measuring voltage anyway from looking at the Motorola chip.

Bruce, as Stan pointed out a little further up the page, the AM radio and the signal detection car are doing a similar function. The advantage of the car is it can follow the track and quantify the signal. The AM radio is able to go anywhere, and sniff for other noise sources. It only registers presence, not level.

That's interesting about you hearing the Legacy noise on your stereo tuner. Out of curiosity, are the Legacy and the tuner plugged into the same house circuit? Could the noise be feeding back through the wall and coming out your speakers? When I was a kid, I remember the vacuum cleaner messing up the TV signal when it was on. I'm looking for a connection, but mostly shooting in the dark.

John, my electric bill is just fine. There would have been no way I could have lit the layout with anything less than LED bulbs. They use 9 Watts per 60 Watt equivalent bulb. The whole room takes less than 20 Amps to light, and generates almost no heat. They run, on average, maybe a couple hours a day. Nothing compared to heating water in the hot tub, which is why I turned that thing off, probably for good.

I believe the Antenna lead is Pin 23, on the outside corner, not inboard as the diagram shows.

GRJ, I'll make this comment now just so I can say "I told you so".   If you go direct to an Arduino A/D pin for your transponder you've probably seen the application notes about having a low source impedance.  51k Ohms is not a low source impedance!  The A/D sub-system in the Arduino microcontroller is not hi-impedance relative to an instrumentation voltmeter.   Anyone wondering what the heck I'm talking about, don't worry about it.  GRJ knows what I'm talking about...

Wow, I get hung up on a response to a couple posts and all the gurus show up at the same time.

I now have everything to complete the car, and have started construction. I see that I made a mistake already, easy to fix. I had the cap in series. Only one question, which pin on the board socket is the headlight?

Attached are the plans for the 455kHZ earth ground signal car meter.  The signal car meter consists of a 51K resistor, .1uf cap & a R2LC radio board which I mounted on an old dummy engine with pickups.  Also used a Harbor Freight free-be meter on the 200 u amp range.  The trickiest part of this build, was to solder a wire to pin 13 of the MC3372IC, which is located on the R2LC board.   See the attachments for the schematic, R2LC board pin assignments, MC3372IN spec sheet.

Also attached a summary sheet that Chris Lord of our team but together, on all the items we learned from talking to Lionel's CTO group when we were doing our testing of the TMCC/Legacy signal.

Thanks to OGR forum member Gary Emmich for investigating on how to use the R2LC radio board to measure signal strength.

Hope this helps,

Bob D

NJ-HI Railers

Thank you Bob! That's everything I need. Looks like the worst is behind me on this already. I got the lead soldered to pin 13. That was tricky, not used to work that small.

For anyone else attempting this, take a short length of small gauge wire and tin the end. Get a small bead of solder on the tip of your iron, and very carefully touch them all together on the pin.

Dale:  I'm constantly concerned with errant noises generated by faulty or unfiltered products when Shortwave listening.  There seems to be no end to them in today's appliances and lighting.  Dimmers tend to be the worst offenders if not of the proper kind.  This was the reason I commented on Elliot's lighting much earlier on in this topic.

Elliot:  The Legacy and stereo are connected to 2 different breakers.  I installed a sub panel with 4 breakers in the train room to handle lighting, outlets, switched outlets and extras.  Powering up 3 ZW's has no effect on the radio, but add Legacy and it sets up a buzzing.  You got me thinking that if it isn't the Legacy itself, maybe it's the Legacy power supply...that gigantic wall wort could be suspect.  I noticed one other noisy appliance in the room as of late is my digital soldering station.  To complicate matters, I just added DCS to the layout...but we won't go there.

BobD:  Thanks for the sniffer car info.

Bruce

Bob, one more time!  Please send out correct information.  The outside row of pins on the R2LC is the odd row- Pins 1-23, not as your diagram shows.  The square pad for pin 1 is at the corner, and the antenna pin is at the other corner.

We don't need a bunch of guys trying to build this up incorrectly.  Your diagram would have them putting their antenna on the Serial Data Out pin.

Nick12DMC posted:

BobbyD posted:

Big_Boy_4005 posted:

"Thank you Nick. Patience and persistence are the words of the day. There were those who just said send it in. I'm glad I toughed it out a bit. If you look back on page 4, near the middle, that's where the diagnosis came together. After that, the surgery was easy. This has been a fun topic, getting a lot of people involved, and thinking out in the open."

Now that the legacy base is fixed, I think I'll change the topic title one last time, to something we can run with...

Adventures in TMCC & Legacy

Curious, would this have been solved much sooner if a known good Legacy base was substituted since the TMCC base functioned? Nice layout and construction thread.

While this makes sense and I do agree. Sometimes it's just not that easy. I have my Legacy set away for repair at the moment. My issue was LCS operations so different from Elliot's problem.  It could have been quickly diagnosed with a spare Legacy set. However I only know of around 6 Legacy sets in the whole UK! Arranging to borrow one would have been a bit tricky.

I guess I could spend $300 and have a spare sitting in a drawer. But I have a spare TMCC base for a backup. 

I would like to see a diagnostic utility built in to the LSU software. So you attach your base to the serial/USB lead and your PC and it automatically checks everything is within operating limits. Might need some sort of special lead so it could check the output on the terminal so it could diagnose an issue like Elliot had. 

Nick

We understand and agree with your reasoning. Got a 990 and 993. Our first 990 set had to be returned as it wouldn't power up so we could not operate Lionel then, no base. The second 990 would not charge or power down and was returned. Again we could not operate Lionel, no base. The third 990 set won't charge and the 993 has display issues. As unreliable as these are if we had to do it again we would've gotten two 990's just so we could possibly use one them when the other is in for repairs. 

BobbyD posted:

We understand and agree with your reasoning. Got a 990 and 993. Our first 990 set had to be returned as it wouldn't power up so we could not operate Lionel then, no base. The second 990 would not charge or power down and was returned. Again we could not operate Lionel, no base. The third 990 set won't charge and the 993 has display issues. As unreliable as these are if we had to do it again we would've gotten two 990's just so we could possibly use one them when the other is in for repairs. 

If it weren't for bad luck, you'd have no luck at all!

brwebster posted:

You got me thinking that if it isn't the Legacy itself, maybe it's the Legacy power supply...that gigantic wall wort could be suspect. 

Bruce

 

The Legacy wall wort is just a transformer with a fuse inside the case. No switching, etc.

Dale Manquen posted:

Bob, one more time!  Please send out correct information.  The outside row of pins on the R2LC is the odd row- Pins 1-23, not as your diagram shows.  The square pad for pin 1 is at the corner, and the antenna pin is at the other corner.

We don't need a bunch of guys trying to build this up incorrectly.  Your diagram would have them putting their antenna on the Serial Data Out pin.

Dale

Thanks for the pick up of the reversed diagram.  Hopefully it didn't confuse anyone to much.  I have attached a revised diagram showing the back view of the R2LC board.

Bob D

OK guys. What's the next move? build the meter? and where do you start testing? and how?

Gregg posted:

OK guys. What's the next move? build the meter? and where do you start testing? and how?

Hang on Gregg, I'm working on it. I'll take pictures of the meter construction as I go, and more when the testing is under way. I hope to have the car done later today.

Gregg posted:

OK guys. What's the next move? build the meter? and where do you start testing? and how?

Gregg/all

Very good question!

First, make sure your command unit (TMCC/Legacy) is providing the correct output as described earlier in this tread by using a scope or Dale’s tester. Once you know the command unit is working correctly now you can go through all of the items people have been discussing on how to improve TMCC signal. Listed below are some of the items we checks at the club:

1 )Make sure the “U” terminal connection is not run in the same bundle with earth ground wires. Try to keep earth ground and “U” terminal wires at least 2”-4”
apart. Remember all 110v AC lines have earth ground wires.
2) Make sure your track & engine wheels are clean.
3) Try connecting the command walwart into different ac outlets. NJ-HI railers are in an old commercial building and different AC outlets gave us different
readings.
4) For areas where you have low earth ground signal readings (blinking engine head lights that go solid light when you put your hand over the engine) try running over head ground wires. We ran an earth ground bus wire around 3/4 of the layout with individual leads coming off the main bus to address weak areas. We disguised the wires as wires on telephone or electric poles. You can also run the a ground wire on the top of the layout, but just keep it at least 2+” away from the outside rail.
-5) We initially years ago, installed thin copper strips under the track, which we now removed. The copper strips (earth ground) was not 2+” away from the
outside rail which carries the other part of the signal from the “U” terminal (Item 1 above)

Also, see the attached sheet that Chris Lord put together, from our discussion with Lionel on improving TMCC/Legacy.

If you have individual diesel engines which are giving you problems, you can extend the internal antenna. We have extended engine antennas by just adding additional wire to the existing antenna or you can use 1/2” copper foil to extend the antenna. I found that using the copper foil provided 30% improvements over the same length of 18 gauge wire. I took antenna readings using the signal car and attaching different types of antennas and saw what gave the best results.

For us at the NJ-Hi railers, we found readings in the 38+ ua range satisfied most diesel engines but needed readings in the low 40’s or higher for steam engines. These are the numbers for our layout, yours may differ. By experimenting, you will find the range that engines will work properly on your layout. The earth ground meter will give you real time results as you are making changes on your layout.  It is much easier than trying to figure out if the engine head light on your engine is blinking more or less after making changes.

Bob D

NJ-Hi Railers

rad400 posted:

Attached are the plans for the 455kHZ earth ground signal car meter.  The signal car meter consists of a 51K resistor, .1uf cap & a R2LC radio board which I mounted on an old dummy engine with pickups.  Also used a Harbor Freight free-be meter on the 200 u amp range.  The trickiest part of this build, was to solder a wire to pin 13 of the MC3372IC, which is located on the R2LC board.   See the attachments for the schematic, R2LC board pin assignments, MC3372IN spec sheet.

Also attached a summary sheet that Chris Lord of our team but together, on all the items we learned from talking to Lionel's CTO group when we were doing our testing of the TMCC/Legacy signal.

Thanks to OGR forum member Gary Emmich for investigating on how to use the R2LC radio board to measure signal strength.

Hope this helps,

Bob D

NJ-HI Railers

Adding additional information: 

The red connector next to the meter is a connection point to test  different types of antennas which could be used in your engines to improve signal strength.  I used the four wooden poles at the corners of the engine, to wrap wire/foil around during testing.

The second photo provides a top view of the connections to the R2LC board

Bob D

NJ-HI Railers

gunrunnerjohn posted:

If it weren't for bad luck, you'd have no luck at all!

Got a Cab-1L John. Flawless

stan2004 posted:

...

Yes, resistors in series add.  Or, equal resistors in parallel divide by 2 - you may have 2 100k resistors which in parallel would make a 50k

From what I can see, it looks like this is what the NJ-HR group did.  2 100k resistors in parallel (50k) in lieu of a 51k.

First, I ran TMCC for several years with just a few signal issues on select engines. I addressed those issues with ground plane wires on a couple of areas of the layout that were problematic.  I then added Legacy to the mix and signal issues cropped up everywhere.  

I sent the Legacy base back to Lionel, they upgraded it to 1.3, fixed the early charging issues and returned it to me.  Once again the same signal issues appeared.  I have two separate loops and several blocks which helped in isolating problems.  What I finally found was that two of my PW cars with vibratory motors were playing havoc with the Legacy signal.  These were a searchlight car and the GM generator car.  Once I removed these cars from the various consists the Legacy signal was as good as the TMCC signal.  I solved the problem by adding diodes to the vibratory cars.  However the signal still was not perfect.

Second, I have two 200 amp services coming into my  home.  Each feeds a 200 amp panel for the various power needs.  I had an electrician out to add transfer switches to the panels so I could hook up an emergency generator to one spot and not have to drag extension cords all over the house in the event of power outage (we have a lot of ice storms in North Georgia).  While doing the work he casually mentioned that the current code for our county now required two earth grounds for each incoming service and suggested we bring things up to code.  I agreed and he added the second ground.  All of a sudden all of my signal issues with command control went away. Obviously this makes no sense, but it worked for me and might work for others.

So to sum it up I had an interference problem and apparently some sort of earth ground issue that a second grounding point cured.  While this may not help at all with your problem it may help others along the way.  Good luck!

Bruce

Thank you for joining the conversation Bruce, that's interesting to know.

Personally, I don't think I have the grounding problem, because I wired my entire house, and the inspector made me drive a ground stake for each of my two 150 amp panels as well as bonding them both to the water pipe. I have no water meter to bypass, because I have well and septic out here. I think I had to run #4 copper about 30' to reach from the panels to the water entrance.

There are no accessories, post war or modern on my layout. All I have beside track is Tortoise switch machines. And that may very well be all I ever have.

I didn't think I was having any additional problems with Legacy connected than with just TMCC, but now that you mention it, a couple of engines did make noise when they shouldn't have.

It probably says the original ground was not a proper ground

Ken M

stan2004 posted:

stan2004 posted:

...

Yes, resistors in series add.  Or, equal resistors in parallel divide by 2 - you may have 2 100k resistors which in parallel would make a 50k

From what I can see, it looks like this is what the NJ-HR group did.  2 100k resistors in parallel (50k) in lieu of a 51k.

 

That is correct.  Radio Shack didn't have a 51K, so I used two 100Ks in parallel 

Bob D

Was just reading the following thread about a train mount-able tiny video camera for only $21.  I think the wireless ones are maybe $100 or so? 

https://ogrforum.ogaugerr.com/t...y-layout-for-just-21

If the video electronics doesn't interfere with the signal-strength meter this might be a way to record the signal-strength readings on a route so you don't have to follow the train around.  The video itself could be saved for later comparison or sharing via youtube or whatever to get opinions.  If the camera captured both the changing meter display and the layout in the background perhaps additional eyes can uncover some correlation - maybe a small mirror if the meter lies flat on a flat-car.  Of course there are smaller meters than the Harbor Freight freebie but then the "system" would cost more than 10 cents!

I was actually thinking of using the GoPro to record the readings Stan. I'm just trying to figure out how to get it aimed at the display on the meter. My little test train would be up to 4 pieces: the LC+ engine, the meter gondola, the electronics/antenna car, and now the camera car. Talk about a work train.

You can get a 2.4ghz camera and receiver for less than $50.  How about eBay 111774290029 for $18?

I was thinking some kind of mylar sheet (craft stores) or the like angled so the meter can lie flat on its back.  The camera could then capture the meter reading (albeit upside down) and the moving layout in the background.  If going thru a tunnel (if it's wide enough to handle the meter) you'll need a light since the Harbor Freight meter does not have a backlight for its LCD - but then again what do you expect for FREE?   Upon reflection (!) Harbor Freight also has freebie LED mini-flashlights which you could mount.  So since it appears you already have the video device the budget under a dollar!

That's beautiful Stan. I actually have a small mirror that would be perfect for the task. I'll switch the gon for a flat.

Lighting is no problem. No dark tunnels on the layout yet.

Harbor Freight has a version of that same meter with lighting, but it isn't free.

OK guys, I built the car... Time to figure out why it's not working

Here we have the R2LC with the lead soldered to pin 13. Seems to be a good joint, not touching adjacent pins.

Here we have the donor chassis, a bay window caboose with a light. I folded the original light bracket down flat, and clipped the light to the body mounting bracket.

This is the resistor & capacitor part of the circuit. I didn't have a 51KΩ either, but I had a 47K and a couple 2200's, so 51,400 it is. The resistors are in series with each other and the capacitor is in parallel with them.

I scratched the black finish off a spot on the chassis and soldered on the ground wire.

I cut a block of wood to size, put in the antenna posts, then hot glued the block to the chassis. I also hot glued the two components to the wood block.

I added the ground leg to the resistor cap unit.

There are 3 white wires and one black one tied together here. The ground source soldered to the chassis, the lead from the resistor cap unit, a loose lead which will connect to the R2LC, and the black one is the lead to the meter.

I soldered on a piece of brass wire the correct size to fit the board socket. This black wire comes direct from the pickup rollers.

The white wires are all track ground.

This junction connects the pin 13 lead (black), the resistor cap combo and the other meter lead.

Because the pin diagrams are mirror image, I hope I got this right. I based the placement off the photo of NJ club's unit. The black and white pair are hot and ground. The orange is my antenna, and the odd black wire in the middle is supposed to be the light.

I have the meter set to 200μ DCA.

Any ideas where I went wrong?

Check for voltage on the MC3372 chip - Pin 4 = +5.7V, Pin 15 = Gnd

Thanks Dale, I'll run down and check that. Is that AC or DC? I'm guessing DC. Does it look like I have the power connection correct going into the board?

Pin 4 is a DC voltage.

I assume you added the caboose light so you could send TMCC to the engine to turn it on/off to confirm the R2LC is functional?  It seems to me you should get the light functioning and then move on to troubleshooting the pin 13 meter output.   In my opinion anyway...

Did you move the lead on the meter to the current hole?  You didn't provide a shot of the whole meter, so I can't tell where you've got the leads connected.  You should program the R2LC so you can control it and turn the light on/off as Stan suggests, then you know for sure the rig is working and receiving.

The current hole is only for the 10A DC range.

You might need to add a Program/Run switch if you want to exercise the light.

I got my meter car working this afternoon.  I can see up to 60 uA as the maximum signal.

gunrunnerjohn posted:

Did you move the lead on the meter to the current hole?  You didn't provide a shot of the whole meter, so I can't tell where you've got the leads connected. 

For the low current ranges, it's the same two "holes" as for voltage measurements.  The upper "hole" is only for the 10 Amp DC current range which is not in play at this time.

Thanks Stan, not like any of my meters.  I guess I'm not used to the HF special.

gunrunnerjohn posted:

 I guess I'm not used to the HF special.

But what's nice about the HF special is the battery test mode which puts a load (albeit a small one) on the battery...something you don't find on meters costing many times more than $0. 

I think I have one of those in my wood shop, maybe I have to dig it out.

gunrunnerjohn posted:

Did you move the lead on the meter to the current hole?  You didn't provide a shot of the whole meter, so I can't tell where you've got the leads connected.  You should program the R2LC so you can control it and turn the light on/off as Stan suggests, then you know for sure the rig is working and receiving.

What's the input impedance of these meters? It seems y'all are developing a voltage across the 50K resistor and then shunting it with an ammeter. So...if the input impedance of the meter is 10 Meg or so (typically), you can use the voltmeter. Max reading from the data sheet is 60uA or 3 vdc across the 50K.

Anyway y'all had me confused.

And y'all are making me want to build one of these...

Dale Manquen posted:

Check for voltage on the MC3372 chip - Pin 4 = +5.7V, Pin 15 = Gnd

Just did this test, 0 V. Makes me wonder if this board's no good.

I got it out of a bucket of stuff that Matt had been working on. Not sure if it came out of something or was supposed to go into something. If it came out, it could have had a problem. The only other thing I can think of is the brass pins I attached to the leads aren't making contact in the board socket, hence no juice.

If it came out of the box it might be bad from that Genesis I had to upgrade. Try a different board 

cjack posted:

Anyway y'all had me confused.

The HF special in the 200uA DC-current mode has a 1k Ohm shunt or burden resistor.  With no change in the circuit, they can switch the meter to DC-voltage mode which measures the voltage across 51k Ohms.  Readings of 30-40 uAmps using the 200uA DC-current mode would instead be 1.5 - 2.0 Volts in the DC-voltage mode. 

The reality as I see it is simple.  It doesn't matter what units the meter is measuring (voltage, current, widgets, etc.); the readout gets larger and smaller proportional to the received 455 kHz signal.  And all this occurs over a wide range making it a useful and remarkably inexpensive tool.

Yes, if I were doing it I'd prefer the Voltage measurement mode...but I'm not doing it.  I'd say that ship has sailed and the standard has been set.

Matt Makens posted:

If it came out of the box it might be bad from that Genesis I had to upgrade. Try a different board 

Thanks Matt. That was in a bucket with your name on it. Not sure if I have another. We had ordered a couple of ERR's did they all get installed? I thought there was one for that Lakawanna switcher. You did the MTH TC&W, the MTH CP switcher. I thought there were 3. That board may be from the Genesis. I haven't got any spares that I know of. CRAP.

stan2004 posted:

cjack posted:

Anyway y'all had me confused.

Yes, if I were doing it I'd prefer the Voltage measurement mode...but I'm not doing it.  I'd say that ship has sailed and the standard has been set.

Alea iacta est, eh?

cjack posted:

Alea iacta est, eh?

Translation: "The train has left the station"

Test the board in an engine first, then install it in the car.  Making sure you have control of the light will insure the board is working in the test rig.

gunrunnerjohn posted:

Test the board in an engine first, then install it in the car.  Making sure you have control of the light will insure the board is working in the test rig.

Good point John, I'll have to open up an engine to do that. Not my favorite thing, but I can. I'll have to run down to the hobby store and grab the R2LC tomorrow. Project on hold for today, lots of other projects to work on.

Anything new Elliot?  .   Yes or no is good enough. 

Sorry to report Gregg nothing new on this yet. The one R2LC board that I had loose turned out to have been a dud. It had come out of an engine where the whole TMCC unit was replaced.Now I know the rest of that unit was probably OK and it was just the R2LC.

I'm reluctant to grab one out of a good engine, so the plan is to hit the LHS. Unfortunately, the one guy who has access to the parts is only there for a short time on the weekends. I stopped by last Saturday, but my timing was off by a few hours, too early.

The store is about a 20 mile schlep, and I don't like making special trips if I can help it. I have two more shots this weekend, as I have other train activities both days and can just pop in on my way past. If that fails, I'll just order a few online. Seems like a good part to have spares.

This is still a very important project, and needs to get done, but I can be patient about it. There are plenty of other things to do while I wait.

I'll let everyone know when the party starts.

Elliot, what are you going to do with that R2LC dud?  Are these routinely repaired, saved for scavenger parts, or just tossed?  If the latter, would you send it to me? 

I don't run TMCC and don't plan to but this signal-measurement discussion has been going on for years and I'm curious. I suppose I could get lucky and repair the board using schematics I see on the web...in which case I can mess with the signal-measurement pin13 circuit and Harbor Freight meter using a 455 kHz signal generator rather than a TMCC base.  Whether or not I get it running I'd return it - your worst case out-of-pocket would be ~$3 for USPS First Class package shipping.

Stan, in my world they're just tossed. They are machine made with all those tiny components. Even if I could figure out which one was bad, I probably couldn't fix it. I'd be willing to "donate its body to science". Shoot me an email, and I'll send you the carcass.

They are really fixable except for the programmed chip. You can replace drivers, caps, etc. and the rf chip. The SMD is doable for most folks.

Big_Boy_4005 posted:

Stan, in my world they're just tossed. They are machine made with all those tiny components. Even if I could figure out which one was bad, I probably couldn't fix it. I'd be willing to "donate its body to science". Shoot me an email, and I'll send you the carcass.

Email sent.  Check you junk email folder

cjack posted:

They are really fixable except for the programmed chip. You can replace drivers, caps, etc. and the rf chip. The SMD is doable for most folks.

Oh good, glass half full!  Earlier Elliot reported there was no voltage being supplied to the RF chip so I'm hoping it may be something simple in the power supply which I should be able to repair.  My interest is getting enough working to fiddle with the signal-strength part of the circuit.

Well gang, this project is back on!

I finally found a brave and helpful person at the hobby store, who was willing to risk death, and go back in the parts room and get me what I needed, a couple brand new R2LC's. Always good to have a spare. I should be back up to speed on this by mid week. I've been busy with other stuff while I was waiting.

Q: Does this thing need to be programmed for use in this project, or is it just good to go as is?

Stan, the bad one will be in the mail to you in the morning. I'll be interested in hearing what you find.

Given the radio signal for TMCC, is there a ideal recommended antennal length? 

BTW:  I'm making one of these nifty devices too.  Dunno why, since I haven't experienced any serious reception problem areas on my layout.  But just for fun I guess.

455khz?  Given the wavelength of the carrier is around 657 meters, the longer the better!

If you are talking about a signal testing car, my antenna is a horizontal brass rod 7" long.  I see saturated signals of 62 uA at some places, so this antenna may be on the "large" side.

I HAVE A WORKING TEST CAR!!!

I got the pin 13 lead soldered onto the chip of the new board. Makes a world of difference. The light even works. The meter is reading 36 to 41 on the short section of track I dragged it over. There's a slight problem with the chassis I used, as it is leaning slightly and is making intermittent contact with the ground. Physical problem, not electronic, should be a quick fix.

We're open for business!

Congratulations, Elliot--March is off to a good start!!!

Thanks Carl, but not so fast. I'm going to have to locate another chassis, because this one had the living crap run out of it back at enterTRAINment. The axel bearings are so worn that the side frames are dragging against the center rail extensions on every switch, in a glorious Fourth of July style display. Thank God I didn't fry the new board.

Dale Manquen posted:

If you are talking about a signal testing car, my antenna is a horizontal brass rod 7" long.  I see saturated signals of 62 uA at some places, so this antenna may be on the "large" side.

Dale, could you comment on why you use (or it appears so anyway) a 9V battery to power the R2LC instead of track power?   I realize it allows you to lift it off the track and take measurements anywhere.  I figure a track-powered R2LC installed in a typical engine or accessory car has a steel chassis connected to the outer rail and attendant wiring/harnesses.  It seems this would present a different signal receiver environment, ground plane, shield to the antenna, etc. than a battery-powered receiver on a plastic flatcar bed. 

I'm wondering if the readings will substantially vary depending on the signal-receiver design.  OTOH it may be a your-mileage-may-vary situation where as long as you have a tool to improve your own layout it doesn't really matter if readings compare to another layout...

When you lift it off the track, wouldn't you lose the track common part of the signal?  It would sure be reduced in strength in any case!

Big_Boy_4005 posted:

I HAVE A WORKING TEST CAR!!!

I got the pin 13 lead soldered onto the chip of the new board. Makes a world of difference. The light even works. The meter is reading 36 to 41 on the short section of track I dragged it over. There's a slight problem with the chassis I used, as it is leaning slightly and is making intermittent contact with the ground. Physical problem, not electronic, should be a quick fix.

We're open for business!

Elliot

Good news you got the signal car working.  At the NJ Hi Railers, we found we needed readings in the 40+ range to obtain reliable control of 80-90% the engines.  Steam engines are the ones that need higher signal, due to the antenna they have.  

If you have not already hot glued the pin 13 wire to something, I would do so.  I found it was very easy to break the wire connection to pin 13 if the wire was not secured to something.  

Good luck,

Bob D

NJ Hi Railers 

swise posted:

Given the radio signal for TMCC, is there a ideal recommended antennal length? 

BTW:  I'm making one of these nifty devices too.  Dunno why, since I haven't experienced any serious reception problem areas on my layout.  But just for fun I guess.

 I found that ~ 4"-5" of wire gave the same readings as the typical 1 1/2" - 2" metal antenna, which is found in many engines.  The longer the wire the more signal will be picked up, but I want to simulate what a typical engine would see, so I kept it at 5"

For engines that persist to give you a problem, extending the engine's antenna with wire or 1/2" copper foil will definitely help in the overall performance of the engine.  If you use copper foil, make sure it is securely attached to the sides of the engine with a silicone adhesive.

Bob D

NJ Hi Railers 

Why a battery?  Because that means I don't need a car with a roller pickup and I don't need to worry about center-rail dirt.  That flat car is one of the metal ones, not plastic, and the receiver/battery is grounded to the chassis.

I expect that the readings will only be useful as relative readings.

Thanks Dale, all understood.

OK folks, so I repaired Elliot's R2LC board and have it running with the Harbor Freight meter.  I don't have a TMCC base but am using pro-grade RF signal generator to create modulated FSK/FM signals at 455 kHz.  I'm getting the same "saturated" level as Dale is getting (about 62 uA) so I think I'm good.  Also, with NO 455 kHz signal in the vicinity, I read about 20uA with no antenna plugged into the connector, and about 15uA if I ground the antenna contact.  That seems to square with the 3372 chip datasheet meter sensitivity.  I of course can't test whether the R2LC outputs work since I can't send TMCC commands but as a signal strength meter I don't think it matters.

My next thought is a simple audible circuit that changes tone proportional to signal strength.  So you can listen to the pitch go up and down with signal strength rather than (or in addition to) reading the meter.  As Dale comments, this device is "only useful as relative readings" so when fussing with layout adjustments it seems having a tone going up/down might be useful so you don't have to watch the digital meter readout which might not even be in view if going thru a tunnel or across the room.  Has anyone already done this?  Waste of time?  Comments?

What was bad on the R2LC that there was no signal present at pin 13 on the MC3372?

Just curious...

cjack posted:

What was bad on the R2LC that there was no signal present at pin 13 on the MC3372?

That's an excellent idea Stan, I believe the tone has been suggested before.  I was also thinking of a couple other variations on the theme.  One would be a bar graph on the car so you could see at a glance the signal, and of course the other would be a remote broadcast of the reading so you could see it locally as the car runs around.

The tone is one of the simplest and very effective methods, might just be the ticket.

stan2004 posted:

cjack posted:

What was bad on the R2LC that there was no signal present at pin 13 on the MC3372?

Thanks. 5 v supply?

Well done Stan! You made that look easy. The audible signal idea is interesting, as long as the pitch range is easy enough to differentiate between adequate and substandard levels.

http://www.ti.com/lit/ds/symlink/lm231.pdf ?

Or this...

cjack posted:

Thanks. 5 v supply?

Essentially yes, the 3.3 ohm resistor is in series with the input to the 78L05 5V IC regulator chip.  What thru me for a loop is this version of the R2LC (maybe all do this) has a diode in the ground-leg of the 78L05.  This raises its output voltage by one diode drop or to about 5.7V (instead of 5V).   Elliot said he couldn't read any voltage on the 3372 chip so I knew there was a problem in the 5V circuit...but I had to scratch my head for a bit when I couldn't find a connection between the 3372 ground pin and the 78L05 ground pin!

Big_Boy_4005 posted:

Well done Stan! You made that look easy. The audible signal idea is interesting, as long as the pitch range is easy enough to differentiate between adequate and substandard levels.

That's an interesting point.  As Dale points out, this is a "relative" tool where there's no absolute threshold.  The meter circuit on these chips has quite a bit of variation chip-to-chip so 2 different R2LC boards can give materially different readings for the same signal strength.   I was thinking more in terms of hearing the tone go up and down in real-time as if someone is telling you you're getting warmer or colder.  That is, you really need to look at the recovered TMCC digital signal at the output of the 3372 to know if the signal is good.  Obviously you could have a monstrous interfering 455 kHz signal from wherever that would measure as a high level but be useless.  You are now entering the Twilight Zone of so-called Bit-Error-Rate instrumentation which has its role in the universe but probably not in the world of TMCC.   If I do come up with something you'll be getting it when I return your R2LC so you can be judge and jury!

cjack posted:

Or this...

 

Yes, that's what I was thinking since the 555 has oomph to drive a speaker.  The design problem is whether the 3372's meter output pin with its microamp current-output can drive the 555 without a bunch of additional circuitry.  Additionally, the DC power to drive the 555 and speaker has to come from somewhere.  Burdening the on-board R2LC's 78L05 may be asking too much to drive a speaker so Dale's 9V battery might be the way to go.  Classic case of all ideas eventually degenerate into work!

stan2004 posted:

Classic case of all ideas eventually degenerate into work!

 Or as I'm fond of saying...

Here is my version of a "squealer" for an audio output from the R2LC.  It consists of an inverter/level shifter and a 555 timer chip.  The frequency range isn't really broad, but it is enough to hear changes of RF signal strength.  I am also using my meter in voltage mode for a digital readout via wireless video.  The loudness potentiometer is 500 ohms.  The battery's positive terminal (via a switch) is connected to Pins 4/8.

I needed an acoustical baffle for the rear of the speaker, so I just decided to stick the circuit board inside the a truncated pill bottle that had already donated its closed end to another project.  It is powered off the 9V battery I am using for the R2LC.

I wanted to swap out the Harbor Freight meter for one with display illumination so that my video camera's image would be clearer, but wouldn't you know it, HF didn't have a single one in stock yesterday!  When I go to Camarillo Wednesday, I will go to the main HF headquarters to pick one up.

So now my configuration is complete - test receiver, squealer, meter, wireless video, and a 'scope and one of my Track Signal Strength meters to monitor the output of the Base.

Now what was I going to do with all of this.....?

Cool Dale, but we need a video of your squealer in operation.

OK guys, no more false alarms. The test car is up and running after I replaced the chassis. I finally took my LC+ BN NW2 out of the box and got it going too. I'm ready to take this rig for a spin.

The short test run revealed readings in the 30 - 40 range, and as always when I put my hand near the antenna, the readings jump by about 7 - 10 points. I still wish I could pinpoint what I did to this section to cause the signal level to drop to these unacceptable levels, as it used to work fairly well.

The next logical step is to run the car through some of the areas with known good signal, including the small helix and the upper deck, to determine what an adequate reading is on my layout.

elliot... any new wiring in that area? did things work better prior to adding the lights on underside of that area?

any new construction over it around it enclosing it? any changes to electrical boxes for home and layout area?

is it possible the wire to chicken wire either came loose or a poor connection?

I know may not help but then again something I said might trigger something for you.

[pun] intended here do like dcs folks un-wire things until you find the one wire where that area starts working again, oh now I've done it!  as i chuckle to myself  

good luck and I like that you started test at daytons bluff 

How "new" is that bundle of wires under the track in the photo?  And the control panel, which must have a lot of TMCC "track" signal on all the power switches?

Elliot-

This might not be the case, but sometimes when I "bundle wires" like the picture shown, with multiple over head tracks, I have issues with the TMCC signal...

Sorry to say guys, but the bundle of wire you all seem to be focused on should pose no problems. They carry 12VDC to the Tortoises and ground only for the 24VDC relays. There are no track wires there.

There is a 120 V power cord, but I seriously doubt that is making a difference.

I'm kind of leaning toward the idea that the upper deck casting an earth ground "shadow" on the lower deck.

I still need to run the train around, but I haven't been downstairs the last two days, as I've been helping a local train club move. They have a huge 2 rail layout that has been in place for the last 30 years, and have to be out by the end of the month. You can read about it here.

Elliot, do you use a common ground reference for all your power?  If so, those wires have the track signal on them.

No Dale, those DC systems have no connection to the track, and never will. The only DC system that will come in contact with TMCC, will be the C/MRI detection system. None of those power supplies are active yet. The DC ground will be superimposed on the track ground to activate the C/MRI inputs.