Newbie in need of help


E

engineer_student

New Member
Hello all,

I just joined the site hoping I can get some expertise and maybe some questions answered. First off, I have no experience with model railroads other than seeing them a few times in my life and having a small track with a few cars and an engine that went around the Christmas tree when I was a kid. So, I am a complete NOOB! Haha!

As my username suggests, I am an engineering student at a university here in the US. Not a train engineering student, but a mechanical engineering student. They are probably the same in some respects so I think I should be able to understand some of what is going on with these model trains. :D

Anyway, I work for an engineering center on campus and we have a project that recently came in to help a local train depot museum with their model train setup. They have all of the aesthetics completely done and everything laid in place and installed. However, they only have half of the electronics and wiring done. And since it was volunteer work, there were many people who worked on the wiring and there seems to be conflicting ideas on how to do it. What I am getting at is... the wiring is a royal mess!! hahaha! So, they decided to call in the "experts" to get as much of the wiring and electronics right. We are pretty good at circuit boards, sensors, and things like that but it would be nice if we knew how some of the things worked. We took a visit to the train station and looked over the model and the wiring but didn't really get into details on how some of the things work.

So my first question is, how do the mechanics of the little railroad crossing gates work? Is there an extremely small motor mounted to the side of the crossing gate? Is there some wire that is pulled through the table to a motor underneath? Does it work somehow by just applying a magnetic inductance? I am just curious as I have no experience with these gates, and that is what we are going to be working on as well as the crossing signals, the sensors for the gates, and some lighting inside buildings.

Any and all help and advise is appreciated!
 
It would help tremendously if you could take a few well-composed images and post them. The gates are surely operated by a small servo, not elecro-magentic inductance or anything like that. The only sophistication to come aboard model railroads in the past 20 years has been DCC, or Digital Command Control. The locomotives each have a microchip/decoder that converts a square wave AC signal with digital packet information to which is appended an 'address' code for each identifiable decoder. The decoder converts and meters out the needed voltage in pulsed DC to the can motors that drive the mechanisms in each locomotive.

If this layout is wired for block detection and DC current, it is likely to be a case for an expert to sort out. If it is wired for DCC, it should only have a bus, perhaps a couple of sub buses, but probably only thin feeder wires coming off the bus and rising up to be soldered to the sides of the rails to provide consistent, non degraded, voltage up to the rails.
 
Last edited by a moderator:
Thanks!

I am going to the train station today and I will take as many pictures as I can. Hopefully they don't look too terrible as I only have my cell phone camera. I am sure I will have more questions! The only other thing I know at this point is the train setup uses "curcuitron" boards and things like that. I don't know if that is much help. I found a PDF overview that I have been looking at:

http://www.circuitron.com/301CAT.pdf

I also noticed that these instructions don't really have details on the boards themselves. are there any links to DT-3, DT-4, and FL-3 circuit diagrams?
 
Last edited by a moderator:
call in the "experts"?

If they think college prepares anyone for a wiring project of that nature they are mistaken. College is great for a grounding of math and physics, etc. but nothing of practical application - yet.

Please take that from an EE of over 40-years experience. When I'd hire new engineers out of college it would take about 3 years to actually train them for anything useful. Some were lucky enough to have intern summer jobs during school years and they had an advantage by the time they finished school.

So buy or borrow all the books on the subject you can. Find a Model RR shop and see what Kalmbach books they have on wiring. Don't try to re-invent the wheel. Look online for similar topics.

Plan things in a block diagram and then schematics before you pick up a tool. Learn what wire sizes are needed for various current demands. Make every wire longer than 8-inches neat, orderly and LABELED at both ends.

Have fun and maybe this will not only bring you a new hobby, friendships and maybe even a future career experience.
 
The reason I put experts as "experts" is because they think somehow a college student in engineering is considered an expert. Haha! Sorry, I should have been more clear. I have as much experience as the guys who have been working on that train do. Now, my boss has worked as an ME/EE for about 20+ years so he would be the expert who is working on the project. I have also been working part time during the semesters and full time over the breaks for about 4 years now at the engineering center.

In reality, we are only going to be able to do 40 hours worth of engineering time/wiring time and anything after that would be volunteer. I am trying to learn as much as possible on these boards and everything to be able to get as much of this done as we can in our time frame. It seems very interesting and I may volunteer when I can after this project time is up.
 
Last edited by a moderator:
Great!

Just remember that the "mess" you see wired by the others didn't start out that way. It grew in many tiny steps out of poor planning. Lord help anyone trying to troubleshoot stuff like that when the original people move on and stuff starts to unravel. :eek:

Leave good and accurate documentation behind your work. :)
 
I will have to take some pictures of the "mess" to show just how insane it is! Haha! We have had projects that we do where we go from the ground up and our wiring is color coded, labeled using a labeling machine, and wired extremely clean and neat. It should be fun to troubleshoot this to say the least... Hahaha!

And a quick question... or maybe not so quick... How do I know if it is DCC or block detection and DC? Is there a quick way of figuring this out? Could there be both?
 
Last edited by a moderator:
Say ES,
Although I have no experience with DCC, from what I understand about it is that it requires power feeders to the rail every four or five feet to ensure a consistent flow of the signal generated to any engines being operated.

Now, I have always worked with block wiring, as I am at present in my new [but old] layout, where I've segregated/designated different sections of the main line and sidings
as individual blocks controlled by a simple switch to route power to the block or not.
My power is derived from buss feeders along the edge of the layout to simplify making the main power connections to the switch controllers, which are of the simple on-off or singel-pole-single-throw type.

While I'm not using an form of signals due to the early time period and the branch-line nature of my fictitious RR, if I were that power is/would be derived from the constant power from the transformer and have it own buss to my thinking.


Charles may be able to confirm this.


Hope this is a helps.
 
Isn't someone there that knows if it's DC or DCC? Look at the 'power packs'. What model/make are they? look the model/part number up on line if nothing else.

Or, make a locomotive move on a piece of track. Use an oscilliscope -- or even a voltmeter -- and see if it looks like a high frequency square wave if the loco is moving or not. That would indicate DCC.

With a voltmeter, measure the track voltage. If it's not there when the loco is not moving, and is there, and varies in voltage with loco speed when the loco moves, it must be DC and not DCC.
 
I am now out of my depth. What you list there sounds like relatively advanced DC throttles. It suggests to me that you have a rat's nest to deal with in the wiring and switches to isolate parts of the track system so that only the desired engine(s) move. Sorry.

:confused:
 
Those are DC power packs and that puts me out of any league of helping, as I model with DCC for the simple matter of simpler wiring with a bus and a few feeders. Even then I also have wiring for remote control switches {also called turnouts}.

You probably have a rat's nest of wiring for : 1}electrical blocks to control the trains; 2} wires to control such accessories as the gates and any lights in places like buildings; 3} if it has a train detection system you should have wiring for that; 4} if you have remote control switches {also called turnouts}, you should have wiring for that too.
To boot, the wiring is probably all criss-crossed and intertwined, depending on when it was wired and in what order.
TO make matters worse, if the wiring is all the same color or colors {such as all black or all red blue and yellow} well good luck there.
SOmeone in the ELECTRICAL ENGINEERING dept. may be able to help you out to help determine what wires go to what by following continuity of a wire...

You could also get yourself some model railroad wiring books to help you learn how various features of a layout are wired and then maybe if you understand the basics of wiring a layout better, you may understand all the mess better.

Be sure as you figure things out you MARK each wire at each terminus and in the middle as to what it is for.

That is the best help I can offer you.
________
Mr. nice guy dispensary in san francisco
 
Last edited by a moderator:
ES;

What I would do first and foremost is to get from both Kalmbach publishing and Cartsens Publishing, copies of their books on layout wiring. I would also make sure that it is for DC and not DCC.

I would then trace down and draw diagrams of each and every circuit on that layout and make sure that each was labled on each end and in the middle as well if it is a long circuit.

The Circuitron catalog will tell you what those boards do. From there you should be able to locate where they go.

The important thing is bring order out of that chaos that is under there before you decide whether to scrap it and start over or just make it neat!
 
Well there's some good news... Hahaha!! Oh Lord, what did I get myself into?!

Well the museum was closed when we went over there, even after they told us they would be open, but oh well. we will for sure be there tomorrow. At least the wiring for the most part is exposed and easy to get to under the table. But like some of you have mentioned, it is a mess and there are wires going everywhere! Some of the boards are just hanging down and not even mounted to the frame. Another thing is that the servos that drive the gates weren't installed from what I remember so I am assuming we have to drill holes for those and mount those as well. I will be sure to detail everything and try to label things and make them as neat as possible before I start something. It is a little difficult with only 40 hours of time and buying books would be out of my own pocket.
 
If it were me, I'd start by finding all the thin wire feeders that terminate at the rail feet. They'll be soldered at the rails and should be soldered or suitcased at the bus...or sub. But I would keep working up the inverted system and finding myself closer to the trunk in order to establish what was what. Maybe colour code the rail power network and then find a way to label everything else.

DCC is so much simpler, except that shorts management is very important to keep decoders from frying in the 400 msec it takes to get them red hot. The DCC systems have very good circuit protection for that purpose, but you can break the entire layout into power districts and use circuit protectors for each of them. A 12 volt 2 amp tail light bulb wired in series into a sub bus is a cheap and effective indicator of location and a buffer for the amperage. Much cheaper than a $20-40 circuit breaker.
 
With power-block wired DC, accessories everywhere, and a time limit, I'd be inclined to just rip it all out and start fresh. Take notes before you rip stuff out, and take pictures (more important than notes imo, especially if you know where each pic was taken). DEFINITELY draft up a schematic. When you do cut wires, leave enough to solder to.

Crossing gates (the ones I've seen anyway) have detectors (either IR LEDs or photoresistors) between the rails a short distance to either side of the crossing. These connect to a circuit board (which will hopefully be labelled), which drives a gearmotor or servo to move the gates. The boards need to connect to power somewhere, probably from a separate or accessory transformer.

Sounds like you've bitten off quite the project. Good luck. :)
 
Well we were able to go to the museum yesterday and I took a few pictures of everything I could see "clearly". Unfortunately my card reader decided not to work on me so I can't upload the pictures until I get an SD card adapter/reader. Hopefully I can do that soon enough.

Another board I found was a Circuitron AR-2:

http://www.bakatronics.com/shop/item.aspx?itemid=533

There is a trolly in the middle of the whole thing that doesn't work as of now but it is supposed to stop at two or three stations and do the same in the reverse direction and then repeat. I am assuming that is what the above card is for. I tried to trace some of the wiring but it was quite a mess. I could tell what was the power to the tracks because of the thicker gauge wire and I was able to trace wires from circuit boards up through the table to respective lights and sensors.

I started off just at one railroad crossing by looking at an FL-3 (flashing lights) board connected to a DT-3 (grade crossing detection) board. It looked like there were three wires going from FL-3 up to the crossing gate flashing lights. The wires out of the "L" and "R" ports had small resistors on them. I think I wrote down the right color code but I am still trying to figure out how to read it. There was also a wire out of the "01" port going to the lights as well. On the bottom of the FL-3 board, there are three wires from ports "-" "+" and "C1" connected to "-" "+" and "out" on the DT-3 board. Now the part I am confused about are the sensors that are connected to the DT-3 board. There are three ports, "SD" "S1" and "S2". there is a wire from S2 to a photoresistor but the other wire is not connected, just hanging there, but also spliced with a wire from another photo resistor. That wire has a connector where the splice is. The other photoresistor has another wire with a connector just hanging there as well. I am assuming both those connectors plug into the DT-3 in either "S1" and "SD"? is this correct? Which would be which?

I need to work on getting those pictures!
 
Those board designations are Circuitron boards. Go here;

http://circuitron.com/

On the main page on the left side will be a "Contact Us". By sending them an e-mail they should send you the instructions for each board underneath the layout. Unfortunately, the "Support" section isn't in use yet.

I would also download their catalog, its free! While it doesn't have complete instructions, it does show the general diagrams for the boards in question.

Good Luck! :D
 
The TECH 4 MRC 260 is a DC controller with momentum and brake built in. The user manual (which is laughable) is linked to at the bottom of the link the OP originally posted.

Angie
 
You must log in or register to reply here.



Back
Top