# Track testing car



## CliffyJ (Apr 29, 2009)

I'm having a vague idea that, if it works, might be useful for track testing. 

This isn't something I'm actively working on yet, but I wanted to raise it for conversation. 

For testing of one's track, the main thing that comes to my (rail-powered) mind is continuity. Other factors (e.g., gradient, roll, gauge, distance, velocity, etc.) have their place, but I'm going to address just continuity at the moment. 

So here's the idea, for what it's worth.

[*]Power pickup:[*]A car, having metal wheeled trucks[*]Wiring from both trucks, but with a switch to take one of the trucks off-line[*]Power coming from the trucks goes through a full wave bridge rectifier[/list][*]So, now you have...[*]Rectified DC, good for DC or DCC[*]Ability to switch between 1 and 2 truck pickup[*]In a package you can drag behind a loco, or kick along the track[/list][*]App #1: Audio Continuity Checking (simple version) [*]Relay, coils powered via track power[*]Battery, powering an alarm[*]Relay contacts, NO, close on non-continuity, powering the alarm[*]Result: a car that beeps when it gets to problem power areas (joiners, dirt, whatever)[/list][*]App #2: Audio Continuity Checking (variable version)
[*]Same, but with more advanced circuitry to vary the pitch or volume as continuity varies along the track[/list][*]App #3: DC Metering [*]Mount a DC meter on the roof of the car [*]And/or output jacks for a digital meter[/list][*]App #4: Visual Continuity Checking (simple version) [*]Mount a green light on the roof of the car, powered by track voltage[*]Mount a red light on the roof of the car, powered by relay + battery[*]You see green as it goes along, but flashes of red where there are issue[/list][*]App #5: Visual Continuity Checking (better version) [*]Similar, but the car body is a translucent lampshade, and the lights back-light it, giving nice visibility along the way[/list][*]App #6: Audio Continuity Checking (variable version)[*]Same, but with more advanced circuitry to vary the intensity or color as continuity varies along the track[/list][*]App #7: Combo approach, involving:[*]Level 1: Audio alarm (on/off) and visual indication (on/off, or green/red)[*]Level 2: Audio alarm (variable in volume) and visual indication (variable in intensity)[*]Level 3: Audio alarm (variable in pitch) and visual indication (variable in color)[/list][/list]
For gradient or roll measurements, an electronic inclinometer could come into play. And it could be, of course, entirely battery-powered.

For you battery and steam guys, is there anything you tend to measure along the way? 

Just messin' around as usual... 

===>Cliffy


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## iaviksfan (Dec 27, 2007)

I remember a LONG time ago, in HO, Walthers had a car that had a steel ball in it that would roll and trigger a light if stopped to fast or incline was to steep. They also had the Oscar and Piko? Anyway, Something along those lines would be a good starting point. 
Greg R.


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## jwalls110 (Dec 12, 2012)

I wish I was more electronically inclined. I like the concept however.


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## CliffyJ (Apr 29, 2009)

Thanks guys. 
Greg, the rolling ball thing seems like a no brainer. With all the gradient issues we in G-guys face (in view of extreme terrain we sometimes have to deal with), I'm kinda surprised that there isn't a large scale equivalent. 
OK, maybe not a rolling ball in G gauge, but an inclinometer. Regardless, great data point. 
What's the "Oscar" you refer to?
Cliff

PS, here's a cheap device for digital angle measurement. Maybe there's an easy way set it up for audible set points, don't know.
http://www.amazon.com/AccuRemote-Di...1378862041


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## toddalin (Jan 4, 2008)

I like to keep it simple. I clean the track before running. If an engine stalls at a certain point, I clean that bit a bit more. If the engines run good, all is well.

If you jump up to clean a spot every time that thing beeps, you'll go crazy in short order.


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## CliffyJ (Apr 29, 2009)

Posted By toddalin on 10 Sep 2013 07:17 PM 
I like to keep it simple. I clean the track before running. If an engine stalls at a certain point, I clean that bit a bit more. If the engines run good, all is well.

If you jump up to clean a spot every time that thing beeps, you'll go crazy in short order.
Understood Todd. 

I'm just theorizing.


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## fsfazekas (Feb 19, 2008)

If you do the advanced circuitry where you vary pitch based on voltage received, you may inadvertently create something like a Theremin. This device: 
http://en.wikipedia.org/wiki/Theremin 

But that would be cool...


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## JPCaputo (Jul 26, 2009)

You can add a digital compass that has roll pitch yaw on it to check the track for level side to side and incline using the pitch and roll output.


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## Semper Vaporo (Jan 2, 2008)

Posted By CliffyJ on 10 Sep 2013 05:53 PM 
I'm having a vague idea that, if it works, might be useful for track testing. 

This isn't something I'm actively working on yet, but I wanted to raise it for conversation. 

For testing of one's track, the main thing that comes to my (rail-powered) mind is continuity. Other factors (e.g., gradient, roll, gauge, distance, velocity, etc.) have their place, but I'm going to address just continuity at the moment. 

{snip}

For gradient or roll measurements, an electronic inclinometer could come into play. And it could be, of course, entirely battery-powered.

For you battery and steam guys, is there anything you tend to measure along the way? 

Just messin' around as usual... 

===>Cliffy



I can see value in the electrical parameter measurements, but as a strictly "Live Steamer", all I care about is track continuity and obstructions... and I don't mean electrical continuity... I mean gaps in the rails where the train might leave them. I usually run a (cheap) boxcar around the pike by hand, flicking off twigs and leaves and the odd acorn cap or shell left by a squirrel, etc. and watching the boxcar to see if it derails on some track "discontinuity".

I suppose that knowing the grade here and there would be interesting, but that doesn't change all the much over time and can be measured by a level and some small shims of various thicknesses. Same for cross-level and super-elevation in curves.

If the track is subject to abuse from animals (or kids/non-caring adults) then the gauge might have changed (narrowed or widened) and guard rails at switch frogs and on bridges might get misaligned, so some method of checking the gauge and flange clearances would be of some valve... but anything that would cause problems would probably be found by just rolling a boxcar around once so no electronic "measurements" need to be taken.

Using something expensive to test for mechanical continuity might be a bad idea as if it derails you run the risk of damaging the expen$ive te$t car, whereas a cheap boxcar pushed by hand can derail and the damage ($$$-wise) would be minimal.


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## CliffyJ (Apr 29, 2009)

Posted By fsfazekas on 10 Sep 2013 08:17 PM 
If you do the advanced circuitry where you vary pitch based on voltage received, you may inadvertently create something like a Theremin. This device: 
http://en.wikipedia.org/wiki/Theremin 

But that would be cool...  

The theramin is so cool. Since my wife and I watch reruns of Midsomer Murders ever other night, we hear it played that frequently. 
So yeah, make that car sing!!


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## Greg Elmassian (Jan 3, 2008)

"And it could be, of course, entirely battery-powered." 

Umm... it has to have some battery power to sound the alarm when there is no power ;-) 

I'd find a way to put your 7 amp load on it, although you will need some heavy duty power pickup. 

Todd has soldered jumpers on his rails, so no continuity normally means dirty track, not bad rail joiners. 

Greg


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## CliffyJ (Apr 29, 2009)

Posted By JPCaputo on 10 Sep 2013 08:32 PM 
You can add a digital compass that has roll pitch yaw on it to check the track for level side to side and incline using the pitch and roll output. 
Did you have a product in mind?


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 10 Sep 2013 08:50 PM 

I'd find a way to put your 7 amp load on it, although you will need some heavy duty power pickup. 
Now we're talking...

I was hoping to find an excuse to mount those light bulbs on that orphaned tender chassis, and you've just given the green flag...

So now I mainly need a decent video camera, to get some good night vid of that baby shparking it's way along the rails, ha ha!! 

But I'd have to mask the bulbs, to see the sparks...


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## Joe Johnson (Jan 2, 2008)

On the steam side, you could use the theramin to indicate dips in the track with tone changes on grade changes. I got one that really doesn't like dips. 

Cliffy, Midsomer murder reruns are for quiet Sunday mornings. One each week.


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## Totalwrecker (Feb 26, 2009)

"For you battery and steam guys, is there anything you tend to measure along the way? " 

When built right we just measure the fun..... 

John


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## Garratt (Sep 15, 2012)

When it finds dirty track it could drop the Scotch-Brite pad and scrub backwards and forwards until continuity is achieved. A smart robot train to do the hard work. 

Andrew


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## Garratt (Sep 15, 2012)

Posted By Joe Johnson on 11 Sep 2013 05:22 AM 
On the steam side, you could use the theramin to indicate dips in the track with tone changes on grade changes. I got one that really doesn't like dips. 

My track would play 'Good Vibrations' by the Beach Boys.










Andrew


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## CliffyJ (Apr 29, 2009)

Tough crowd! 

Well, I admit I was going out on a limb with my original posts... But I knew I could count on my friends to help saw that baby off!









Well, back to reality, here's what I've used today for voltage drop checks on my new trackage.

Here's the "dirty meter" car, described on a thread of that title: 










And the new "load car," pulling around 6-7 amps:










The load car is parked as far out as possible, while the meter car was kicked around as I took readings. 

===>Cliffy


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## Dave Meashey (Jan 2, 2008)

Cliffy;

Your load car reminds me of the speed control system for the (very) old Carlisle & Fitch trains. The toy transformer was not invented as yet, so the trains were controlled by a bank of light bulbs wired in parallel. All bulbs screwed in equaled slow. Train speed increased as bulbs were unscrewed from their sockets. Guess the "engineer" really had to wear gloves to avoid burnt fingers. (and this was not even live steam)

Good ideas,
David Meashey


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## toddalin (Jan 4, 2008)

OK, maybe I'm missing something here.

Why do you need the railcar if you are going to clip the load to the tracks?

I thought the idea was that you push/pull the railcar around and any unknown problem areas manifest themselves due to the load while making these spots visible through the lights. I think the best way would be to put the load car and dirty meter on the same railcar.


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## Greg Elmassian (Jan 3, 2008)

Yes, and run 7 amps through the truck pickups? 

And you don't really want to watch the lights, you want to watch a voltmeter, although the lights will get dimmer, you will get flicker with any track pickup system. 

Maybe when he can arrange 7 amp capacity track pickups it can be done that way. 

Greg


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## toddalin (Jan 4, 2008)

And why does it need to be 7 amps to test? Couldn't you do it with half that load? That's not such a big deal and you can easily pull that through a pair of trucks (4 wheels).

At the least, they could be mounted to the same railcar even if one uses clips for the load. That way you are "loading" that section of track that you are testing, and the two pieces (load and meter) always move together so there is less to do/think about/deal with..., but I guess a coupler would work.


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## Greg Elmassian (Jan 3, 2008)

Do you just want to argue? 

Lessee.... 10 amp system and only testing to 7 amps.... would be best to pull the full 10 amps also to be able to test circuit breakers and that the system will ACTUALLY put out 10 amps... 

The more current drawn the easier to see the voltage drop... good enough reason? 

So half that would not be a good idea... and still, you say pulling 3.5 amps through 4 wheels is easy? Well, it won't be a set of ball bearing wheels, and it would be a bad idea to use carbon brushes, so PLEASE show me the product that will handle 3.5 amps on 4 wheels.... I would LOVE to find it.... Pulling even 2 amps through my Aristo ball bearings has pitted the heck out of them. 

Yes, I believe Cliff will mount to the same car, he's getting there... give the guy a chance... was not long ago he was complete newbie. I never thought to find large 24 volt bulbs... 

Greg


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## toddalin (Jan 4, 2008)

Posted By Greg Elmassian on 14 Sep 2013 08:23 PM 
, so PLEASE show me the product that will handle 3.5 amps on 4 wheels.... I would LOVE to find it.... Greg 

I do it with a single set of AristoCraft heavyweight trucks on my fan powered engine. That motor is rated at 4.47 amps.


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## JPCaputo (Jul 26, 2009)

Posted By CliffyJ on 10 Sep 2013 08:54 PM 
Posted By JPCaputo on 10 Sep 2013 08:32 PM 
You can add a digital compass that has roll pitch yaw on it to check the track for level side to side and incline using the pitch and roll output. 
Did you have a product in mind? 

I was thinking about for leveling the track, there are a multitude of small digital 3 axis digital compasses and accellerometers on digikey. This will allow for detection of bump positions and other data. With a chuff axle from an engine on the test car, distance can be calculated. A virtual map can be created to show exactly where each problem is. Probably using an ardunio or similar microcontroller that has multiple inputs, and a-d converters, everything can be done in 1 pass besides clearing the track. Then afterwards download the data on a computer and using some math a map of where all faults can be made, where the track twists, sharp bumps, electrical disontinuity, and more. Then with the map you don't have to look all over to find the problem areas. It would Probably need a simple battery power engine to push/pull the test car or cars.


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## SD90WLMT (Feb 16, 2010)

OK....it's time for me to throw my towel in this mess.. 
1st,.. Cliffy has made incredible progress learning all of this that makes our trains run. As such he is looking for the most reliable layout he can build....kudo`s Cliffy.... 

To clarify for you Todd, yes the fan motor .. may be rated .. at a certain rating, which only indicates the maximum load only. Your fan motor - without measuring - may be less than rated...or expected by yourself...hope this helps... 

My take on the light bulb load car is that it may represent a 7 amp load at that load, but other loads lost thru transmission to reach a distant point on the layout are not being represented here, with a max output of 10amps supply current. 

Also, to me the load car needs be only positioned in one place to allow Cliffy to use his non-load meter to work and provide consistent results.... 

My take here guys, nothing more...... 

....Dirk


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## Greg Elmassian (Jan 3, 2008)

Those are probably the best for heavy current, because they are a large brass eyelet that the axle rolls in.... and maybe the best ones might be the brass sleeved ones used for Aristo tender pickups...

But you still are not running 7 amps all the time... and you are picking up on THREE wheels, so ALL the current is going through one wheel in this case.... Bring it to my house, let me hook up my 8 amp load to it and I will bet you that I melt something.

This is designed for continuous power, and twice what you are claiming you are pulling.

I remain unconvinced that you have a solution that meets the requirements... 7 amps continuous over extended time and the car is NOT rolling.

I'm in San Diego, bring it by.

Greg


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## CliffyJ (Apr 29, 2009)

Thanks guys; fun conversation. 

Just to clarify, here's what led up to this "load car":

03 Sep 2013 03:11 PM, under "Dirty Meter" thread:

For each far point (farthest from center feeds), in my case three farthest loop points,



1. Attach an 8 amp load (light bulbs?), and switch on the DCC

2. Working from center, take voltage readings and note them on a track plan 

3. For any abrupt change, track down the offending joiner or switch connection or whatever, and fix it

4. Keep going to the furthest points



BTW, Greg had alerted me (and others, in various threads) to the need of an applied load for vdrop readings. We'd discussed the means, and this bulb thing was the experiment.

Just as an FYI, without the load, my voltage (using the "dirty meter") is 20.5 right at the center main feed. With the load, it went down to 18.4 at that same location. 

The load was clipped on at a far ends. Kicking the meter car from center feed point to that far point, I took readings along the way, and noted them on the track plan. The whole reading process took less than an hour for the entire layout. Could have sped it up, but it was such a nice day I felt like taking my time. 

I didn't attempt rail pickups, for two reasons. First, I don't have any spare pickup trucks that look like they can handle it. Second, letting it roll with the meter car might, I think, produce an undesirable variable in contact / load draw, as far as the voltage readings are concerned. Unless you maybe had a nice string of pickup trucks wired in parallel to reduce that issue.

So, I confess that I only car-mounted the bulbs for grins... 

... and to help justify starting this thread...









===>Cliffy


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## CliffyJ (Apr 29, 2009)

Posted By JPCaputo on 14 Sep 2013 09:50 PM 
Posted By CliffyJ on 10 Sep 2013 08:54 PM 
Posted By JPCaputo on 10 Sep 2013 08:32 PM 
You can add a digital compass that has roll pitch yaw on it to check the track for level side to side and incline using the pitch and roll output. 
Did you have a product in mind? 

I was thinking about for leveling the track, there are a multitude of small digital 3 axis digital compasses and accellerometers on digikey. This will allow for detection of bump positions and other data. With a chuff axle from an engine on the test car, distance can be calculated. A virtual map can be created to show exactly where each problem is. Probably using an ardunio or similar microcontroller that has multiple inputs, and a-d converters, everything can be done in 1 pass besides clearing the track. Then afterwards download the data on a computer and using some math a map of where all faults can be made, where the track twists, sharp bumps, electrical disontinuity, and more. Then with the map you don't have to look all over to find the problem areas. It would Probably need a simple battery power engine to push/pull the test car or cars. 
Though I don't have the knowledge to design what you describe, your ideas on such a product make sense to me. True, in the end it might be beyond the price point for most. But in view of the perennial issues one might have (oxidation, frost heave, critters, corrosion, etc.), why not? And perhaps it could be a low-cost DIY thing that just evolved out of sharing of ideas & circuits and parts lists. 

Be fun to try, at least.


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## toddalin (Jan 4, 2008)

Posted By CliffyJ on 15 Sep 2013 11:37 AM 
Thanks guys; fun conversation. 

Just to clarify, here's what led up to this "load car":


BTW, Greg had alerted me (and others, in various threads) to the need of an applied load for vdrop readings. 

Just as an FYI, without the load, my voltage (using the "dirty meter") is 20.5 right at the center main feed. With the load, it went down to 18.4 at that same location. 


===>Cliffy


The situation is that the "load car" loads down your power pack and this reduces the voltage to 18.4. As long as all of your joiners and switches are good you will see this same 18.4 volts across the railroad.

But say that your load is on a good section bringing the power level down to 18.4 volts. Now say you put your dirty tester on a "bad" section because there is a bit of corrosion at the joint on either side of that section. But the sections to either side of the bad section (or at your load car) may still be good because they receive current from the other direction around the loop, or a feeder down the line. 

So, the upshot is that you are not pulling the load through the bad section and that bit of corrosion may not manifest itself by displaying a reduced voltage drop (below 18.4 volts) on your dirty car. That's why it is important to put the load where you test that section of track. 
If you are not receiving power from the "other direction" (e.g., point to point with one feeder) you only need to "load test" the furthest section(s) from the feeder and if it is good, every joint leading up to it must also be good otherwise the current would not reach the furthest sections. If there is a problem, you work back from there.


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## JPCaputo (Jul 26, 2009)

Posted By CliffyJ on 15 Sep 2013 12:13 PM 
Posted By JPCaputo on 14 Sep 2013 09:50 PM 
Posted By CliffyJ on 10 Sep 2013 08:54 PM 
Posted By JPCaputo on 10 Sep 2013 08:32 PM 
You can add a digital compass that has roll pitch yaw on it to check the track for level side to side and incline using the pitch and roll output. 
Did you have a product in mind? 

I was thinking about for leveling the track, there are a multitude of small digital 3 axis digital compasses and accellerometers on digikey. This will allow for detection of bump positions and other data. With a chuff axle from an engine on the test car, distance can be calculated. A virtual map can be created to show exactly where each problem is. Probably using an ardunio or similar microcontroller that has multiple inputs, and a-d converters, everything can be done in 1 pass besides clearing the track. Then afterwards download the data on a computer and using some math a map of where all faults can be made, where the track twists, sharp bumps, electrical disontinuity, and more. Then with the map you don't have to look all over to find the problem areas. It would Probably need a simple battery power engine to push/pull the test car or cars. 
Though I don't have the knowledge to design what you describe, your ideas on such a product make sense to me. True, in the end it might be beyond the price point for most. But in view of the perennial issues one might have (oxidation, frost heave, critters, corrosion, etc.), why not? And perhaps it could be a low-cost DIY thing that just evolved out of sharing of ideas & circuits and parts lists.   
 
Be fun to try, at least. 


Hi, it definetly can be a DIY thing. Probably can give the program and wiring diagrams away, and sell a kit or prebuilt version if someone wants to buy it. I am willing to give some of the programming a try. Have to dust off some trig, geometry, and coordinate conversions to do it.


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## CliffyJ (Apr 29, 2009)

Thanks Todd. The plot thickens!

Since this particular for of "testing car" started as part of the "dirty meter" thread, I posted specific readings there (15 Sep 2013 12:19 PM) that may apply to what you're saying.
http://www.mylargescale.com/Communi...fault.aspx

If I'm understanding you correctly, I should move the load car to the point of reading. And that's why the meter car could / should be integrated with the load car, which would indeed argue for a through-the-trucks connection approach. 

Correct?

Cliff


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## CliffyJ (Apr 29, 2009)

Posted By JPCaputo on 15 Sep 2013 12:49 PM 
Posted By CliffyJ on 15 Sep 2013 12:13 PM 
Posted By JPCaputo on 14 Sep 2013 09:50 PM 
Posted By CliffyJ on 10 Sep 2013 08:54 PM 
Posted By JPCaputo on 10 Sep 2013 08:32 PM 
You can add a digital compass that has roll pitch yaw on it to check the track for level side to side and incline using the pitch and roll output. 
Did you have a product in mind? 

I was thinking about for leveling the track, there are a multitude of small digital 3 axis digital compasses and accellerometers on digikey. This will allow for detection of bump positions and other data. With a chuff axle from an engine on the test car, distance can be calculated. A virtual map can be created to show exactly where each problem is. Probably using an ardunio or similar microcontroller that has multiple inputs, and a-d converters, everything can be done in 1 pass besides clearing the track. Then afterwards download the data on a computer and using some math a map of where all faults can be made, where the track twists, sharp bumps, electrical disontinuity, and more. Then with the map you don't have to look all over to find the problem areas. It would Probably need a simple battery power engine to push/pull the test car or cars. 
Though I don't have the knowledge to design what you describe, your ideas on such a product make sense to me. True, in the end it might be beyond the price point for most. But in view of the perennial issues one might have (oxidation, frost heave, critters, corrosion, etc.), why not? And perhaps it could be a low-cost DIY thing that just evolved out of sharing of ideas & circuits and parts lists. 

Be fun to try, at least. 


Hi, it definetly can be a DIY thing. Probably can give the program and wiring diagrams away, and sell a kit or prebuilt version if someone wants to buy it. I am willing to give some of the programming a try. Have to dust off some trig, geometry, and coordinate conversions to do it. Reminds me of the kits that Dave Bodnar sells, and the plans he gives away...


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## toddalin (Jan 4, 2008)

Posted By CliffyJ on 15 Sep 2013 01:01 PM 
Thanks Todd. The plot thickens!

Since this particular for of "testing car" started as part of the "dirty meter" thread, I posted specific readings there (15 Sep 2013 12:19 PM) that may apply to what you're saying.
http://www.mylargescale.com/Communi...fault.aspx

If I'm understanding you correctly, I should move the load car to the point of reading. And that's why the meter car could / should be integrated with the load car, which would indeed argue for a through-the-trucks connection approach. 

Correct?

Cliff 






Exactly.


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## CliffyJ (Apr 29, 2009)

Well, since there's more activity on this thread than the "dirty meter" one, and since they are dovetailing, I'll focus more on this one in the hopes of sparing further confusion.

So I had time today to retest one leg of the layout, moving the load along with the meter. The following chart shows the readings at various points, with the key as follows:

UnL: reading without applied load
Load1: reading with load at position Load 1
LocL: reading with load at meter position











First off, I've no idea why the unloaded readings are .4 to .5 higher than the 20.5 I've been getting before today.

Todd, to your point, the unloaded voltage is almost perfectly consistent across the layout. Weird how I got higher readings at the furthest point! But I'm using a cheap meter.

To Greg's point, that's not an indicator of voltage drop. This map is a pretty graphic example on why I needed to add the load!

As to deciphering the "loaded" readings, remote load vs. local, I'm still trying to get my head around the pattern /causes. Head hurts though, time for dinner.... 
But since the "local" load readings are lower, that seems to say that a local load is more indicative of local phenomena, as I think you were saying Todd.

Bottom line: I'm losing about 1.2v at the extremities, and (per more conversation w/ Greg on the "dirty meter" thread) I need some jumpers around certain switches. 

BTW, here's the new setup. Compatible couplers would have been nice, but I needed to have room for the clips in between anyway. 










Yeah, it would be nice to have it all the same car, and not to have to clip and unclip, stooping constantly. But, the re-test went ok, once I enlisted some help from Bethany, our youngest:










And before someone asks, no, I didn't make her unscrew the hot light bulbs, or clip any hot leads. No twelve-year-olds were harmed in the making of this thread.









===>Cliffy


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## CliffyJ (Apr 29, 2009)

Back to the broader notion of testing cars in general, if voltage drop was something I was needing to check once a year (say), I'd consider messing around with the following:
[*]A simplified, all-in-one rig (meter, load, whatever)[*]An ammeter (wired to read DCC)[*]Maybe all on one board, to easily set on a flatbed or in a gondola[*]Maybe a trailing set of pickup trucks, w/ dean's plugs and #10 wire connecting? Seems too long. But robotic rail pincers seem a tad much.







[*]Ability to haul it w/ a loco... I think it's safe for the loco, but...? [/list]Not very sophisticated, but what the heck.

===>Cliffy


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## toddalin (Jan 4, 2008)

Yes Cliffy, this illustrates my point exactly.

Note that on the interior spur when the load is remote the voltage is as high (17.9) as the average elsewhere. But when you put the load directly on that section, it shows the most drop (16.1), most likely because of what is happening at the connections around/about at the turnout indicating a possible problem in that area.

But you never would have known this if you didn't locate the load in that area.


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## toddalin (Jan 4, 2008)

The next obvious step is to determine the minimum load that will produce near that 16.1 volts in that area. If it only takes 2 amps to get a similar drop, the need for 8 amps becomes moot and you could probably use ordinary wheel pickups to accomodate the load on the dirty car.


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## JPCaputo (Jul 26, 2009)

Theoretically the drop is directly proportional to the load. V=I*R. For real world application with a thin layer of oxidation, a small load (electrically speaking ) may not be enough to overcome the oxidation, and a heavy load will break through the oxidation and provide a good path. The down side is that a very bad connection with a heavy load will cause arcing and overheating and much worse problems. A light load will show the very bad connection without the major problems caused by using a heavy load.


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## Greg Elmassian (Jan 3, 2008)

Yep, I don't see any logic in reducing the load... 

And Ohms law clearly states if you reduce the load the voltage drop will reduce... by this logic, no load will provide full voltage everywhere, therefore you cannot find anything wrong









The more load, the easier it is to find the points of resistance, also, why test for 2 amps if you have a 10 amp system, like buying a Ferrari and only driving it 30 mph. 

Greg


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## toddalin (Jan 4, 2008)

The voltage on the older Train Engineers likes to go to full scale when the load is removed. Even if the trains are only running at 12 volts, the digital read-out on my point-to-points drifts to full scale once the trains reach the ends and are waiting to go the other direction. As soon as the trains reverse, the voltage shows what it is under a load.

It would be nice to know about what the real "loaded" voltage is when the trains are "parked" at the ends So do I need to put some big azzed load on the system just to get an idea of the loaded voltage?

No, that's ridiculous. A 1000 ohm resistor consumes less than 0.03 amp of my supply and the voltage readout is within about 0.2 volt of the loaded system and can be accomodated by a 1/2 watt resistor housed right in the panel. So why should I consume all that extra power and generate all that heat even if I have 10 amps capability for a bit of precision when a pert near will do fine?









If a lesser load lets him get a near similar reading and allows for the use of wheel pick-ups that make the whole thing work that much easier, I see that as a good thing and worth the sacrifice of a fraction of a volt.


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## Greg Elmassian (Jan 3, 2008)

You really do not understand. 

Your logic is flawed. 

I'd answer your last post and point out your mistakes, but you just want to fight. 

Forget it, I'll use my knowledge to help people that appreciate it. 

Anyone who wants any more info, email me privately. 

greg


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## toddalin (Jan 4, 2008)

Posted By Greg Elmassian on 15 Sep 2013 06:16 PM 
You really do not understand. 

Your logic is flawed. 

I'd answer your last post and point out your mistakes, but you just want to fight. 

Forget it, I'll use my knowledge to help people that appreciate it. 

Anyone who wants any more info, email me privately. 

greg Why not let Cliffy just unscrew one bulb on the 16.1 volt section and report his findings? Better yet, tell us what the voltage will be when he does before he does it.


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## toddalin (Jan 4, 2008)

Posted By JPCaputo on 15 Sep 2013 05:28 PM 
Theoretically the drop is directly proportional to the load. V=I*R. For real world application with a thin layer of oxidation, a small load (electrically speaking ) may not be enough to overcome the oxidation, and a heavy load will break through the oxidation and provide a good path. The down side is that a very bad connection with a heavy load will cause arcing and overheating and much worse problems. A light load will show the very bad connection without the major problems caused by using a heavy load. 
This is basically how I feel. I don't believe that a bad connection exactly follows V=I*R because as a bad connection is subject to excessive loads, it generates heat. This heat then raises the resistance through the connection partially negating the increase in load and removing linearity from the equation.

Theoretically, the reading with 1 light bulb should be 17.0 volts if it were as simple as that, which is why I asked that it be measured.


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## JPCaputo (Jul 26, 2009)

Exactly, with a bad connection linearity goes to hec to an extent. The voltage can drop exponentially more with a bad connection that arcs ( seen it first hand shortly before the solder and plastic melted and bright arcing in a connector, while wondering why I had low voltage across a resistor). Increased resistance increases the voltage drop. 
. With a single lamp, essentially a smaller load, the heating will be less therefore less damage can occur. The voltage should still be much less than expected. 
one thing for sure is that voltage should not go up as you go further away from a feed point as long as there is a load.


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## Dan Pierce (Jan 2, 2008)

Todd, I use the old train engineer and I use an incandescent lamp on my RR to load down the 'leaky' Aristo mosfets. 
It also serves to show me that power is on the rails as I attach this bulb to my track away from the feeders. 
When I have a power issue, I immediately know whether power is missing form the track without having to find a meter.


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## CliffyJ (Apr 29, 2009)

I agree with Greg, it seems more better to approximate the full load to see what the v-drop really is at that current. Otherwise, you have to try to correct your voltage numbers for that current delta, and hope for the best. 


I'm not quite sure what I'm talking about, but here's what I came up with. 

Let's say you had I1, current at testing, and you know what your full current (I2) is. Call it I1 = 2A, I2 = 10A. 
V1 is volts measured at test time, and you want to extrapolate volts under full current, V2. 
If R was constant, R= V1/I1 = V2/I2; R would drop out, and V2=V1*I2/I1. 

But R isn't constant; and all three variables are -- at least I think they are -- varying between the reduced-current and full-current scenarios, for a given reading. Which would mean you can't extrapolate V2.
If you used the above equation, and V1 was 19v, you'd have V2=95v, which wouldn't make sense. 
So with all three elements in flux (V, I, R) it makes sense to try to force one of them to be the same -- in this case, I. Because you're measuring fluctuations in V, as a function of R (different positions on the layout). 

Whether I'm getting it or not, a different benefit with using near-full load has been testing my PSX units, in their trip settings. I was messing up there, and I didn't realize it.


This has been a very useful dialog for me, thanks everyone.

===>Cliffy


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## CliffyJ (Apr 29, 2009)

Posted By Dan Pierce on 16 Sep 2013 04:33 AM 
Todd, I use the old train engineer and I use an incandescent lamp on my RR to load down the 'leaky' Aristo mosfets. 
It also serves to show me that power is on the rails as I attach this bulb to my track away from the feeders. 
When I have a power issue, I immediately know whether power is missing form the track without having to find a meter. Dan,
What voltage / wattage, and how do you hook it up?


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## toddalin (Jan 4, 2008)

I think you may need to look beyond that. What about those "fine" jumper wires under turnouts and crossings? (Maybe you don't have any.) What amperage are your toggle switches rated for? While these things may be able to handle the typical loads on a day to day basis, what happens when you subject them to extreme extended currents that they would never see in real life after they've been exposed to the elements for several years? Once you burn though a few of these and have to pull the track just to replace them, you'll see why pulling that much current through them is not a good idea. 

To use someone else's allusion, if someone has a $500,000 Ferarri that can make 650+ hp, that doesn't mean that it is a good idea to strap the car to the dyno and take it up to redline, in overdrive, exposing the transmission, shafts, joints, etc. to speeds that they would never see in real life, and leave it in that condition for an extended period just to find a miss in the engine because of a loose spark plug wire. That would be a real waste of a nice Ferarri.


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## JPCaputo (Jul 26, 2009)

Posted By CliffyJ on 16 Sep 2013 12:47 PM 
I agree with Greg, it seems more better to approximate the full load to see what the v-drop really is at that current. Otherwise, you have to try to correct your voltage numbers for that current delta, and hope for the best. 

 
I'm not quite sure what I'm talking about, but here's what I came up with.  
 
Let's say you had I1, current at testing, and you know what your full current (I2) is. Call it I1 = 2A, I2 = 10A. 
V1 is volts measured at test time, and you want to extrapolate volts under full current, V2. 
If R was constant, R= V1/I1 = V2/I2; R would drop out, and  V2=V1*I2/I1. 

But R isn't constant; and all three variables are -- at least I think they are -- varying between the reduced-current and full-current scenarios, for a given reading. Which would mean you can't extrapolate V2.
If you used the above equation, and V1 was 19v, you'd have V2=95v, which wouldn't make sense. 
So with all three elements in flux (V, I, R) it makes sense to try to force one of them to be the same -- in this case, I. Because you're measuring fluctuations in V, as a function of R (different positions on the layout). 
 
Whether I'm getting it or not, a different benefit with using near-full load has been testing my PSX units, in their trip settings. I was messing up there, and I didn't realize it.
 

This has been a very useful dialog for me, thanks everyone.
 
===>Cliffy 


I think your math may be off. The two resistances are different. With equal voltages to get different current you need different resistances. If you use the power supply voltage (V1), load voltage (VL), load resistance (RL), load current (IL), you can find the track resistance (RTr). Using the equation V1=VL + ( (VL / RL ) ) * RTr When applying 24 volt power supply voltage, and 19 volts at the load, assuming 10 amps load ( 1.9 ohms). The equation results in 0.5 ohms from power supply to track load point. This is respectable. Applying 16 volts as the load voltage, (24-16)/(16/1.9)=0.95 ohms. About double of the other reading. For finding pure track resistance there are several ways, One way to find ideal track resistance is to take a 6 ft length of track, jumper 1 end and measure to get a per 6ft length resistance. Check the resistance of the meter leads alone as a baseline, and the track resistance is above this baseline.


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## Dan Pierce (Jan 2, 2008)

I just use a 24 volt LGB bulb. I believe these are about 50ma.


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## CliffyJ (Apr 29, 2009)

Back to a couple simpler questions. 

Greg, when I first put the bulbs on the track, the PSX breaker kept tripping with both. I'd had both jumpers soldered on the board, which should have allowed 8.9A. So I clipped the jumpers, and learned how to program the thing. But when it kept tripping even at the 12A setting, I said heck with it, and went all the way to 15A (max). It then allowed both bulbs.

Question: it's risky to leave it at the 15A, because then the main booster breaker would trip, right? Also, is this an inductive vs. other kind of load thing?

The other thing, I pre-calculated the 2 bulbs (24v, 100w) to pull around 7.1 amps, at 20.5 (initial) DCC volts, but I wanted to try and check. Unfortunately, my meter has only a DC amps setting. So I put a 10A diode in series with the bulbs, and found that 1 bulb pulls 2.0A, 2 bulbs 4.0A. So perhaps without the diode, they're pulling 8A. 

Question: does that make sense? Also, would a regular AC ammeter work with DCC? 

Cliff


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## JPCaputo (Jul 26, 2009)

Light bulbs are a highly nonlinear load. When off they are a dead short, or very low resistance. Drawing many times the current rated for the short duration until they heat up. A sensitive over current trip will pick it up and trip. 


For the 4A versus 8A calculated, DCC is a PWM (pulse width modulated) system. The pulses are make the output roughly a 50 -70 percent duty cycle, with pure DC as 100 percent duty cycle. The 50 percent duty cycle means only 1/2 the time power is flowing, the other half it is not. 


The switching speed is fast enough that when put through a rectifier and cap that the full voltage is seen. However a light bulb responds fast enough to show the difference in the meter. 


A true RMS meter will read properly. Meters that are not True RMS most likely will not read properly. The harbor freight ones are all over the place, even checking a decent DC power supply with ripple.


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## Greg Elmassian (Jan 3, 2008)

a light bulb on DCC is 100% duty cycle. 

check your facts......


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## Dan Pierce (Jan 2, 2008)

SO, if pulling 10 amps with a 50 percent duty cycle, the wire has 20 amps half the time. Thus the need for 12 guage or better wiring for our trains.


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## Greg Elmassian (Jan 3, 2008)

jeeze.... it is bipolar square wave guys!!! not unipolar square wave. 

it goes minus after it goes plus.... rectified it is dc .. sigh.... you guys really don't know this? 

and you need 10 gauge if you want to deliver 10 amps anyway. 


Greg


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## Dave Meashey (Jan 2, 2008)

To bad that none of the manufacturers has tried to adapt a version of this for such a purpose, but I suppose the return on investment would not justify the development costs. Bachmann had an HO version years ago that could clean track. A large scale version could probably test and clean at the same time. Anyway, thought it might make a good modeling project for sombody.

Rode the prototype back in the early 1980s as part of my job. It was a rough-riding vehicle - only two axles actually carried it. All the other wheels were for testing the track geometry.

Yours,
David Meashey


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## CliffyJ (Apr 29, 2009)

Posted By Dave Meashey on 18 Sep 2013 08:16 AM 
... It was a rough-riding vehicle - only two axles actually carried it. All the other wheels were for testing the track geometry.
David Meashey

Any pics or diagrams of that David? Just curious, I've not heard of such a thing before, sounds intriguing.


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## Garratt (Sep 15, 2012)

Cliffy, you missed David's 'this' hyperlink. 

Andrew


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## CliffyJ (Apr 29, 2009)

Sure did, thanks Andrew. 
Here's a video: 
http://vimeo.com/48063864 
Check out the tunnel scanning laser midway thru the video. 
Very cool.


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## CliffyJ (Apr 29, 2009)

For the record, thanks to a tip from Greg, I was able to measure the DC amps with 1 & 2 bulbs, by tapping the meter in between the power supply and booster. 
1 bulb: 3.5A; 2 bulbs: 6.5A. 
These are 24v bulbs, 100W. 

Seems like I could use a third bulb to bring it closer to 10A, maybe 9 or 9.5. 

But, I'd need to solve a problem first w/ onset current, because the bulbs pull too much initially.


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## toddalin (Jan 4, 2008)

Posted By CliffyJ on 22 Sep 2013 02:15 PM 
For the record, thanks to a tip from Greg, I was able to measure the DC amps with 1 & 2 bulbs, by tapping the meter in between the power supply and booster. 
1 bulb: 3.5A; 2 bulbs: 6.5A. 
These are 24v bulbs, 100W. 

Seems like I could use a third bulb to bring it closer to 10A, maybe 9 or 9.5. 

But, I'd need to solve a problem first w/ onset current, because the bulbs pull too much initially. 

You can use in-rush suppressors. Use a pair in parallel. 


2.5 ohm, 6.5 amp inrush suppressors


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## Greg Elmassian (Jan 3, 2008)

Cliff, those are the Negative Temperature Coefficient (NTC) thermistors I told you about. 

That one is 2.5 ohms, You might only need one ohm, and many circuits call for one ohm. I'd buy an handful of one ohm ones, and if you need more resistance, put two or more in series. 

Regards, Greg


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## CliffyJ (Apr 29, 2009)

Thanks Greg!


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## CliffyJ (Apr 29, 2009)

I finally got back to this load car project, but now the objective is getting it closer to full load draw. 

My (NCE) system should be good for 10A, and the two bulbs were only pulling about 6.5A. So I wanted to put a third bulb on, but the inrush current on that 3rd bulb kept tripping the breaker. 

With Greg's help I found a 1 ohm / 10A thermistor, and bought 5 of them just in case. They're available from Digikey and other places:
http://www.mouser.com/ProductDetail...AlK6hOPGzQy2pwLNf7nsG7uGtXAhFHyqm%2bwJXa6vw==http://www.digikey.com/product-deta...ND/1873480
http://www.ametherm.com/datasheetspdf/SL121R010.pdf

After adding the third socket to the board, I clipped one thermistor and tried the thing out.

First off, it worked perfectly. I couldn't clip the leads on with all 3 bulbs screwed in, that tripped the breaker. But by gradually screwing in the 3 bulbs, no breaker broke or chirped on the PSX. 

Using Greg's method of measuring the (DC) amperage between PS and booster, here are the results:
0 bulbs: .3A1 bulb: 3.7A2 bulbs: 6.6A3 bulbs: 9.2A 
9.2 is good enough for me. 

Notice that the totals aren't linear. So if one wanted to get more precise, or closer to other amp totals, one could mix and match different wattages. Here are some 24V bulb examples:

25 watt: http://www.amazon.com/Industrial-Pe...amp;sr=1-6 
40 watt: http://www.amazon.com/General-41924...mp;sr=1-15 
50 watt: http://www.amazon.com/Industrial-Pe...amp;sr=1-2
60 watt: http://www.amazon.com/Sylvania-1064...mp;sr=1-14 
100 watt: http://www.amazon.com/Industrial-Pe...amp;sr=1-3

When we were picking out the thermistor, Greg advised me to get the lowest ohm rating possible (at full current), to get the dissipated heat down. Even with this one (which is rated .03 ohm @ max current), that baby got hot!

I remembered that my cheap multimeter had a temperature probe, so I clipped that onto the thermistor. With all three bulbs, it quickly got to over 300 degrees F, and was still climbing as the plastic clip melted down! So I kept adding thermistors in parallel, and taking temps. With all five in, the temp finally stabilized at 170 degrees F, which seems fine. 

Here's the final diagram:










Here's how it looks.




























The car is entirely optional.









===>Cliffy


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## Greg Elmassian (Jan 3, 2008)

Great job Cliff, you have found an inexpensive and effective way to make a heavy load for testing that can run continuous duty. 

Now, to have some real fun, you can set your voltmeter to AC millivolts and measure on each side of a rail joiner (the same rail). 

With this heavy load, all the current helps show up weak joiners easily. Now you can locate the exact joiner causing a problem. 

Regards, Greg


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## CliffyJ (Apr 29, 2009)

Thanks Greg, it's been a fun collaborative effort!


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