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Ya Mike. First, great point about the wheels being capable of creating that resistence. I would think literally anything applied made of atoms contributes to resistance.
True, but if the wheels are virtually any metal or alloy, it's really only the oxide (or other contaminants) on the contact surfaces you have to worry about. Oxidation on the surface of any metal will dramatically increase the conductivity of any contact running through that surface. Such oxidation is increased and speeded up through chemical contaminants on that surface and/or by electrical arcing caused by poor contact, so a periodic and thorough track cleaning is one of the most-prescribed 'first aid' measures suggested to avoid (or cure) performance issues.
 

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Discussion Starter · #45 ·
Testing Amps.

Rather than a new post I figure someone can answer this in here quick.


So to test my amp draw of whatever I choose, I need to set up my multi meter in line with the circuit to get the reading if I'm correct. Besides probes I'm not sure if the Fluke comes with clip on leads. What do you normally do to tap into the circuit? ie. a specific different set of leads you use for amps. Furthermore, how do you create an easily accessible place to tap in on your circuit.
 

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Discussion Starter · #47 · (Edited)
How do you connect to the power supply? Is there any place between the power supply and the tracks you use screw connectors like a terminal strip? Any place you can insert a terminal strip?
Just conventional, Fastrack has female crimps under track to spade connectors attatched to transformer, to power brick, to wall outlet
Could I instead connect the fastrack wires to a fused terminal block, then through to the transformer. Would that protect the transformer and also be a place I could tap for amp checks.
 

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You can go back and edit your post. The three dots upper right of the post. Click there and the drop down will have "Edit". Make your changes. And "Save", lower Left.
True . . .but I always hate it when someone edits out the subject of subsequent posts, leaving readers to try to puzzle out what was being discussed. I typically use that method when I catch an error before anyone notices it; in this case, I'll just stand with my error and your correction. Thanks!
 

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Just conventional, Fastrack has female crimps under track to spade connectors attatched to transformer, to power brick, to wall outlet
Could I instead connect the fastrack wires to a fused terminal block, then through to the transformer. Would that protect the transformer and also be a place I could tap for amp checks.
You can add the fuse. Convention adds the fuse inline with the center rail feed. Your amp meter would also go inline when measuring amps. You can have a center rail feed to fuse to meter to transformer. You'll need aligátor test leads for the Fluke or aligátor cables and clip them to the test leads. The double ended alligator cables are available at Harbor Freight for $3.

Always remember to put the red lead in the 10 amp receptacle on the Fluke. If you forget and leave the red lead in the "V" position, you'll likely wind up with a $200+ brick for a multimeter. I've been playing with electronics since a wee lad and I have my fair share of bricks :)

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Discussion Starter · #50 ·
Awesome. Thanks. I see what you mean Mike. So that's no problem. I am that way with computers. They are my comfort zone, So things like a cab2 controller are absolutely no deterent for me. It's electrics (which I hope you can see I'm learning a bit about from you and the google machine) as they apply to model railroads (and beyond of course)

So how come I see people using all these terminal blocks, but they don't, use fused terminal blocks. Is there any downside? Is it just $?
 

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... So how come I see people using all these terminal blocks, but they don't, use fused terminal blocks. Is there any downside? Is it just $?
I don't use fuse blocks as I run prewar Lionel. The thermal breakers in the postwar transformers protect the transformer and the loco wiring against shorts (derailments, etc.). Though I did have to replace the thermal breaker in my Lionel 1033 transformer after it failed open.

If I recall correctly, there was a modern loco with two pick up rollers. The rollers were individually wired at opposite ends of the Loco.'s PCB and tied together on a PCB trace. So when the Loco derailed with one roller on the center rail and the other on an outside rail, the short went right through the PCB trace and burnt it up. That's one reason to use fast fuses (hard to beat but need to be replaced) and magnetic breakers (much faster than thermal breakers, but pricey) for the new stuff.

I had ordered 5 amp fuses to replace them in my multimeter (remember the brick story). I ordered cheap from China and was willing to wait. I thought I ordered 5 fuses for like a buck two eleven. When I opened the package, there was 50. If I ever need better protection, I'll use them and replace as necessary.
 

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Discussion Starter · #52 ·
So that sounds like a pretty big design flaw for a model railroad engine

While the post war transformers might protect well from electrical spikes causing damage, I trust they do so with fuses or circuit breakers. Seems to be quite a few stories about slow circuit breakers and I have one about unserviceable fuses.

I get my new transformer tomorrow. Hopefully ,other than being proactive and testing out my multimeter, I don’t need it, fused terminals, bus lines or feeder wires. I can keep all that learnin’ for another day.

I’m still just wanting and counting on a let’s say circle of track and an engine connected via Bluetooth that performs lion chief features. When the time comes that the new Cab3 comes out (and not holding breath for that) If I find the desire for that most likely I’ll be getting into this whole shebang
 

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While the post war transformers might protect well from electrical spikes causing damage, I trust they do so with fuses or circuit breakers. Seems to be quite a few stories about slow circuit breakers and I have one about unserviceable fuses.
Well, to be clear, the transformer's circuit breaker is mostly there to protect the transformer, not the rolling stock, and will provide absolutely no protection from electrical spikes. I've literally melted the contacts off several pieces of rolling stock that went astray on the rails before the transformer's circuit breakers finally kicked in.

Since I run almost exclusively post-war rolling stock and don't have much if anything with a circuit board in it, I really don't need protection from electrical spikes (which can be generated by a number of items on the typical layout), so I settled on some inexpensive 5 amp thermal circuit breakers (if I did have electronics, I would likely have opted to use the much faster, and much more expensive, fast-acting circuit breakers, or at least added fast-blow fuses).

Since I installed the external circuit breakers, I've had them kick out numerous times with no further rolling stock damage. I also recently opted to get a set of TVS diodes, which when installed across the transformer's output, will provide protection from voltage spikes . . . though to be honest, I haven't yet gotten around to installing them . . . :rolleyes:
 

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Discussion Starter · #54 ·
What is the traditional way for those who have a lot of rolling stock to ensure all wheels are seated correctly that are going to be receiving power. Do people use the ramps when placing anything on the rails?
 

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What is the traditional way for those who have a lot of rolling stock to ensure all wheels are seated correctly that are going to be receiving power. Do people use the ramps when placing anything on the rails?
I know there are some O scale re-railers out there, and there may have been other options developed that I missed, but I've always just relied on the Mark 1 eyeballs and fingertip braille methods for getting the rolling stock back on the rails. I did frequently use one when I was doing HO quite a while back, but for the bigger stuff it's just always been easier and more convenient to do manually anywhere I need to reset the rolling stock.
 

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So can someone quickly explain for me what happens to electricity when there is a derailment.
Well, there's at least three possibilities:

- First (and all 'round best, if you desire to limit the potential mischief), a derailment can 'open' the previously connected circuit, and the electricity no longer flows from the source through the device being intentionally activated. Simply put, the train stops running, the lights go out, etc. Other than no longer getting the desired result, no damage done (unless your engine took a header off the edge! 😳).

- Second (and probably potentially the most damaging), a derailment can cause a "short circuit", or "short" for, err, short, meaning that, instead of being routed by the intended path to and through the device being activated (and in the process using the electrical energy to activate that device), the derailment has insead created an alternate path for the electric current to flow, without having to do all that pesky 'work' in the process. Since the 'short' typically has a lower resistance to the electric potential (voltage), the resulting current flow can be massively larger than the components are designed to handle, potentially putting every section of that circuit in jeopardy. One of the worst shorts I ever had was a trolley that derailed with the center rail pickup somehow short circuited across the track. The ZW's circuit breaker never popped, but the resulting current was sufficient to literally melt the pickup off the trolley, and char the length of the (in hindsight, much too small) track feeder wire, resulting in copious columns of smoke rising above and from below the layout! 😲

- Third (and the most quirky and hard to predict), a derailment can cause electricity to flow through unexpected paths, with unexpected results. In other words, a derailment can create unexpected connections and potential paths for the electricity to flow. Sometimes the results can be as bad as a dead short, but often the result is just puzzling or even not readily apparent.

For the third category, sometimes you don't even need an actual derailment -- for instance, to allow 'old school' activation of the crossing gate and bell at the dual track crossings on my layout, I used a separate power supply rather than track voltage to activate the crossing features through an insulated outer rail section on each track, relying on the rolling stock wheels on one track or the other to bridge the outer rails and provide a path to the common ground. Both crossings worked flawlessly . . . until trains on both tracks arrived at the same crossing at the same time, in which case the five amp circuit breaker protecting one or the other of the circuits would immediately pop open, every time, stopping that train in its, err, tracks! I still haven't figured out what I did wrong (I suspect there's some back voltage from the two running engines feeding a differential voltage back into the common ground that's at fault, but so far I haven't had the time to run it to, err, ground, and just ended up temporarily disconnecting the second track activation wires). sigh

Oh, and a fourth possibility: derailments (or even intermittent poor contact with the rails) can also create voltage spikes and other 'noise' in the electrical circuit, which can wreak havoc with any sensitive electronics connected to that circuit. Since I generally run post-war conventional equipment, that's of little personal concern or consequence to me, but if you do rely on modern electronics for all the zoomy features built in to your rolling stock, you would be well advised to take measures to protect your investment! ;)(y)
 

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Well, there's at least three possibilities:


- Second (and probably potentially the most damaging), a derailment can cause a "short circuit", or "short" for, err, short, meaning that, instead of being routed by the intended path to and through the device being activated (and in the process using the electrical energy to activate that device), the derailment has insead created an alternate path for the electric current to flow, without having to do all that pesky 'work' in the process. Since the 'short' typically has a lower resistance to the electric potential (voltage), the resulting current flow can be massively larger than the components are designed to handle, potentially putting every section of that circuit in jeopardy. One of the worst shorts I ever had was a trolley that derailed with the center rail pickup somehow short circuited across the track. The ZW's circuit breaker never popped, but the resulting current was sufficient to literally melt the pickup off the trolley, and char the length of the (in hindsight, much too small) track feeder wire, resulting in copious columns of smoke rising above and from below the layout! 😲
But a dragging derailed boxcar makes pretty sparks!! ⚡⚡
 
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