Starting an Old Project

I finally started something I have been talking about for a while now - my model railroad. I drew some plans several months ago, and just a couple weeks ago I finally sat down and figured out what it would take to make them a reality, then I got started. About two weeks ago, on a day off, I went over to the lumber yard in town and picked up some lumber to build the benchwork, and then I put it together that afternoon. It is not a large railroad, and I already knew exactly how I would assemble the benchwork, so it went together pretty fast. All I really had to do was cut and assemble. The benchwork ended up being pretty sturdy, as you can see in the pictures, for two reasons. First of all, I studied construction management, and tend to build everything like it is the foundation for a skyscraper, and second, the 2x4's were cheaper than the 1x4's, which I had originally planned on using.

I will be using two inch extruded foam insulation as the surface on which the layout will be built. That provides a surface that is plenty sturdy, yet easy to work with. I decided not to glue the foam to the framework just yet, because I can do some of the basic wiring before putting it in place. Once the foam is in place, any work on the wiring has to be done from beneath the layout, which means working overhead. Since it is easier to work on something you can stand over, I decided to install the basic wiring before I glue the foam in place. Today I had a few hours to kill, so I finished off the wiring in one section of the layout.

The layout is divided into sections, for portability. I do not have any intention of taking it to shows or anything, but it will very likely have to move in the future. We do not plan to stay in Glendive permantly, and even if we did, we would eventually buy a house. The layout bolts together in two places. The wiring will have jumpers connecting the sections, which can be removed easily, and so the entire thing can be taken apart and moved when that becomes necessary. The bolts will ensure that when the railroad is reassembled, the sections will line up exactly as they were designed to.

I am waiting for some electrical parts to arrive, and when they do I will have a few more things to install before the foam. Once they are in place, I'll glue the foam insulation to the top of the framework, and start laying track. I started cutting the foam today to the proper size so putting that on will be a simple matter of gluing it down. I should be able to get that started this weekend. I plan to lay, electrify, ballast, and weather the tracks before getting too involved in anything else. after that will come the structures and other scenery. Since the layout will represent a fairly industrial part of a fictional town, the scenery will be mostly industrial. There will be very little natural scenery, but it will maximize operations by including quite a few industries served by rail. Besides the industries, there will also be a passenger depot and a rail car shop.

Patches and Decals

Recently I discovered, or perhaps should say, rediscovered Microscale Decals. This led to a few unanticipated small projects. I had a little time to kill and was browsing their railroad products, mostly to see if they had anything interesting. A lot of times when I browse sites like that, just to kill some time, I find a lot of interesting things and add them to the shopping cart. Later when I finally look at the cart, I find I really do not have any use for most of the stuff in there, and need even less of it! But it is fun to cyber window shop sometimes.

Former BNSF 9290, patched to become 8190.

As I was browsing the selection of decals on the Microscale website, I actually found quite a few things I could use. For some time I have had engines on my roster that still have either BN or ATSF reporting marks. Since I model more or less current BNSF operations, I have been wanting to patch these units for a while. I also have had a few BNSF engines with the wrong number on them, which needed to be patched and renumbered. I discovered that Microscale made decals for just those purposes. They have decal sheets with colored patches, which are designed to closely match BN green, ATSF yellow, and BNSF orange. A close match is all that is needed since most patches do not exactly match the rest of the locomotive. They also have a sheet with various size and color BNSF stencils, which can be used over the colored patches. I bought a sheet of each.

Former BNSF 9223, now renumbered,
still needs new number boards.

Besides BNSF decals, Microscale has quite a large selection of other decals. I also found some Amtrak decals for Phase 3 locomotives. It was described as Phase 3 and heritage units, although I bought it too quickly, not realizing that it meant Phase 3 heritage units. As it turns out there is one for Phase 4 heritage units, too. I did find some useful decals on the Phase 3 sheet anyway, although a few days later I also went and bought the Phase 4 one. I have had a few old Athearn blue box units in Amtrak's Phase 4 scheme, one of which as unnumbered. With just decals, I figured I could make a close representation of the Phase 4 heritage unit, which as far as I can tell, was never commercially produced.

Former ATSF 650 has received a BNSF stencil below the
number.

Once all the decals arrived, I went to town working on my engines. I had a pair of BNSF SD60M's, which were once numbered in the 9200 series. When BNSF bought the SD70ACe's, they decided to number some of those in the 9200 series, and consequently the SD60M's were all renumbered into the 8100 series. I patched out the numbers on the models and put the proper 8100 numbers on them. Some other units required patching it all the Burlington Northern lettering, and replacing it with a BNSF stencil. Fortunately, with the green patches provided, that proved to be a fairly straightforward task too. On a couple of the Geeps, I decided to add stencil that says, "Remote Control Equipped" as well. Typically older Geeps can be found working yards, and many of them have been equipped to operate as a remote control locomotives, especially at larger yards.

BN 2522 has been stenciled for BNSF.

The ATSF units had were the easiest to patch. Many of them have kept their original paint scheme and some even still say, "Santa Fe" across the long hood. On those, usually a yellow BNSF stencil is found below the number on each side of the cab. A few of those were included on one of the decal sheets and I used them on my two Santa Fe units, that wear the red and grey "Warbonnet" paint scheme. Now all my BNSF "heritage" units have been updated to the current standard.

BNSF 2522 is a remote controlled unit.

On the Amtrak decal sheets, I found everything I would need to make a phase 4 heritage unit, even including the stripes. My unit had the stripes and everything, it just had no number. While the heritage scheme is not exactly the same as the phase 4 scheme was, it is very similar. I have thought about painting the unit to make it an exact match, and I probably will in the future, but for now I am going to settle for jut the decal work. I had a few things to add to that, such as the GE builders stickers and the American flags, but other than that, it was a simple matter of adding a number, 184 in this case, and putting the 1971 and 2011 stencils on either side of the locomotive body.

Amtrak #1 got a flag and a sign on the door.

Since I finished most of those projects, I have discovered that Microscale also carries all the small warning and data decals for GE locomotives. They probably have something similar for EMD units, although I did not look. I have a Dash 9-44CW that has no warning labels on it at all, and so it is getting dressed up now. It is interesting how the locomotive never really looked incomplete to me, but now that it is getting a lot of those decals, it looks considerably more complete. It is one of those things that I never noticed, but once I did, I could not help noticing it again every time I looked at the engine. Decals are easy to add to an engine, or any other rolling equipment, and they can add a lot to the overall appearance of a model.  Most of these projects can be finished in an hour or two, even at a leisurely pace.

Legos and Model Railroading

When I'm decaling a car, I find it a little annoying when I have finished one side of the car and I have to wait for the decals to dry before I can decal the other side of the car.  This is not a problem when I am decaling a whole fleet at once, because I can then go and decal the other cars, and by the time I am finished doing that, the first one is ready.  However, with only one or two cars, you are left with some down time between decaling the sides.  I fixed this problem today with legos.

The problem is not that the wet decals will fall off the car if you turn it over, it is that if anything, such as the desk you are working on, touches the wet decals, it can mess them up.  I fixed this by building a device out of legos that touches the car only on the top and bottom edges, which are very unlikely to be decalled, so any decals on that side of the car can dry upside down while you work on the side that is facing up.

This device holds most types of rolling stock.  I built it around a box car, but it can also hold just about anything else.  I wouldn't try putting a flat car in it, and I would be careful with a tank car because there is a chance it might hit the decals on those.

I am not going to go into a long explanation about how to build this.  A similar device could probably be made out of styrene or wood, but I just thought legos would be easiest for this project.  Instead I will share my photos and you can study them to see how it works so you can build your own out of whatever material you like.

A box car in the device.

The walls of the device are high enough to prevent the car from being bumped out.

The device only touches the car's top and bottom edges, making it safe to flip a car over with wet decals to work on the other side.

Detail of the device without a car in it.

Some Big Changes

Lately I've made a few changes in my train room. I actually don't have a dedicated train room, just an otherwise empty area that I use to work on my trains. I had a small 2 foot by 12 foot layout in that space, but the reason I've never really talked about it on here is because there has never been anything to talk about. Recently I decided it was a waste of space and I tore it down.

One of the biggest things preventing me from tearing it down for a while was that I had a bunch of modeling supplies underneath the layout and I had no other home for them. I wasn't sure I'd be able to find a home either. So before I tore down the layout, I cleaned and organized everything underneath. I put all the tools in a toolbox and found a home for that. I have two rolling cabinets with modeling supplies in them and cleaned them out. Supplies directly related to building a model railroad, such as track and foliage and wire, got put into plastic bins which are now in my closet. The rolling cabinets were then filled with other modeling supplies, such as paint, styrene, and decals. I had a big box full of code 100 track, but where I don't use code 100 and most of it wasn't any good, I threw it all out. Finally, I have two small bookshelves where most of my trains are stored, and I left those where they were. I then tore down the layout and got rid of the tables.

This leaves me with a big open space. I am not giving up on modeling, I am just changing my focus. Since I have no layout at home, I am going to focus on building my fleet of rolling stock and locomotives for when I do have a layout. This means I am going to use the space for a workbench. I already have one workbench where I assemble kits and do repair work on my models. I am going to keep that one and use it for kit assembly and such, and I am building a second bench that will have a built in test track, and will be used for decoder installation and other electrical work. The two workbenches, the two rolling cabinets, and the two bookshelves as well as a third that I need to get, will occupy the now empty space where my layout used to be. I still have a display case, and that will stay where it is.

The workbench I am building will be a pretty nice one, if I say so myself. I found a cheap desk for sale, and I am modifying it for my needs. It will certainly not be pretty, but it will be functional. The top surface will be where I do my work, and I will have a roll-out test track, similar to computer desks with roll-out keyboards, so that I can test the things I am working on without needing more space dedicated for a test track. The test track will be able to run both DC and DCC locomotives, and it will also be a fully functional programming track. When that workbench is finished, I'll write a blog post about it, focusing on the electrical work powering it.

Also, a little update on the Lakes Region Model Railroad. Chris and I have not had time to work on it lately, because of the cruise in February and because we both have been getting more hours at work recently. However, his grandparents come home from Florida in two weeks, and the layout has to be back in storage by then. They are planning on selling the house this summer, so we will not be able to use that space again, so the layout is once again being stored indefinitely.

Product Review: SoundTraxx Tsunami TSU-1000

This week, I thought I would do something a little bit different.  We have done several product reviews in the past, but they tend to be locomotives and rolling equipment.  Model railroading encompasses more than locomotive and freight cars, so I thought I would do some equipment that makes it operate.  Today I want to talk about a DCC sound decoder, which I rather like.  SoundTraxx offers a wide range of DCC decoders for mobile and stationary applications.  I have known about them for quite some time, but because of the price, I have been hesitant to purchase any of their products.  Recently, I found a distributor offering a kit to upgrade Athearn's recent P42DC locomotive models to DCC and sound.  These kits featured the TSU-1000 decoder, which is part of SoundTraxx's Tsunami line of products.  The decoder in the kit was programmed with modern sounds from General Electric's FDL-16 prime mover.

The Tsunami line of products is SoundTraxx's line of sound decoders.  They offer both sound and non sound decoders for stationary and mobile use, although they are best known for their sound decoders.  The TSU-1000 is a one amp DCC sound decoder, and they offer different options for the sounds programmed onto the decoder, which encompass a variety of steam and diesel sounds.  They generally specify the prime mover programmed onto the decoder, and then several options for horn, bell, and other sounds are also programmed onto the decoder, allowing the user to customize the sounds to match the prototype.

When my kits arrived, I discovered a few things about SoundTraxx decoders.  When one purchases a decoder from SoundTraxx, that is all they purchase.  Even if it is a sound decoder, it typically does not come with a speaker, baffle, or harness for easy installation.  The distributor that sold me my decoder kits had included all of those additional parts, which is a good thing because I would have not known that they are not included.  While a complete package, including all the required parts would be nice, I can see the benefits to not including them also.  It does allow the user to buy speakers and other parts specifically suited for the locomotive in which the system will be installed.  It also gives the buyer the option of finding the parts from another supplier, possibly at a lower price.  I can appreciate these benefits, but I would also think that a first time buyer with limited electronics experience may want something that includes everything.

Assembly of all the parts was not difficult.  It does require some basic soldering skills and some patience, but it was not difficult.  Assembling the baffle is a simple matter of gluing a couple of plastic parts together.  Once assembled, the speaker can simply be pressed into the baffle.  The speaker must be soldered to the leads that come from the decoder.  All the decoder leads must also be soldered to their appropriate location within the locomotive.  The decoder does come with a diagram, which shows where each wire should be connected.  Additionally, NMRA compliant 8-pin plugs are available, and the decoder leads could be soldered to that instead, if the user wanted an installation that could be easily removed in the future.  I tried this method on one decoder, but found it difficult to solder the wires to the tops of the pins.  On the second decoder, I connected it directly to the locomotive.

Once everything is assembled, it must somehow all get inside the locomotive.  With any sound decoders, this can be a little tricky.  It always seems as if there are about a thousand miles of wire, and finding a place for the speaker, where it will not cause other problems can also be challenging.  Fortunately, Amtrak units are car body type engines, and while space is not ample, it is not too cramped inside either.  Before I closed up the locomotive, I set it on the tracks to test everything.

When the locomotive is placed on the tracks, the decoder goes through a start up sequence.  It produces sounds that sound like a locomotive starting up and then idling.  I was actually quite impressed with the sound quality, although I did find the default volume level to be a bit loud.  That is easily adjusted, and can be adjusted on the main track if your DCC system allows main track programming.  After I got the volume turned down a little, I pulled out the cheat sheet, included with the decoder, and tested the various sound functions.  The only one I really did not like was the horn.  There was another cheat sheet with the various horns on the decoder, and instructions on how to change the horn sound, so I changed it, and tested it again.  Then I throttled up slowly, so I could hear when the decoder went to the next notch of power.  Overall, I was impressed with the sounds.

I have a DCC system that allows programming on the main track, provided the DCC decoder in question can be programmed on the main track.  I find this feature very handy, and I am not sure I would ever buy a system without it.  Every decoder I had used previously  had been fully programmable, as far as I was able to tell, on the main track.  I tried to change the address on this newly installed decoder, and found that it would not accept the new address.  Having never run into this problem before, I looked through the documentation included with the decoder, and found nothing.  There were several references to a complete decoder manual online, and so I checked that out, and then found that SoundTraxx decoders cannot have their address reprogrammed on the main track.  Most other things it seems are programmable on the main track, although there are a few things that SoundTraxx decoders will not accept unless it is moved to a programming track.

Overall, I am happy with the pair of decoders I purchased.  Eventually I would like to put sound in all my engines, because I like what it adds to operations.  I do plan to purchase more decoders from SoundTraxx, though I will probably purchase the speakers elsewhere to save a little money.  I do think the decoders are a good purchase, and a good value.  The sound quality is high, yet the price is comparable to most other sound decoders.  I have three SD70MAC's, and I am eager to try the TSU-1000 with the EMD 710 prime mover sounds next.

Roadbed

When Chris and I built the Lakes Region Model Railroad, we had a few goals we wanted to accomplish with it.  First, the layout had to be portable.  This meant it had to be lightweight, durable, and easy to set up and take down.  Second, it had to be inexpensive.  That meant we had to design and build the layout keeping in mind what we have, and maybe sacrificing a few luxuries that were too expensive to justify.  Finally, the layout had to be able to withstand cold weather, because we were building it in an unheated garage.

One of the first things we had to figure out was roadbed.  Neither of us wanted to use plywood or homosote, so the debate was between cork and foam.  We ruled out cork because it was more expensive, Chris had a supply of foam roadbed already, foam is easier to work with, and it is lighter than cork, reducing the weight of the modules.  We glued the foam roadbed to the layout, and nailed and glued the track in place on top of the roadbed.  This worked very well while the layout was set up.

The end of the school year came around, and the layout had to come down.  We didn't have a place to set it up, so we drove it to Nashua and stored it in the shed in my backyard.  In doing this, we learned that the layout was much lighter than we thought it was.  All four modules stacked on top of each other only weigh about 30 pounds!  We put the layout away, hoping that one day we could set it up again.

The layout spent two hot summers and one cold winter in the shed before we set it up again.  The weather extremes had taken its toll on the track.  The foam didn't provide a sturdy enough base for the track, and the track was allowed to bend and twist as the temperature expanded and contracted the rails.  When we set the layout up again, we tore up all the track and roadbed, and we are now replacing the roadbed with cork.  Cork is heavier than foam, but we believe that the extra weight is worth it.  The cork is a sturdy base to attach the track to, it will hold the track in place much better than the foam did, making it withstand the elements better and making it more durable during transport.  The modules were much lighter than we anticipated anyway, so the extra weight is okay, because the modules are still extremely lightweight.  Also, cork isn't as expensive as we thought when we built the layout the first time.

I have never tried using plywood or homosote as roadbed materials, but I have heard of it being done.  I wouldn't want to work with plywood, especially on grades and curves, but it would be extremely durable for a modular layout.  I don't really know anything about homosote, so I can't say anything about it.  But through my experience, I have learned that nothing works as well as good old fashioned cork roadbed.

Picking the Right Paint Color

You want a locomotive for a specific railroad, but nobody makes it, so you have to paint your own.  First, you need to match the paint.  You ask the guys at the club, and they tell you a paint color.  You contact the railroad's historical society, and they tell you another paint color.  You find someone who used to work for the railroad, and he tells you a third paint color.  Finally, you go to a paint specialist, and you wind up with a fourth paint color.  Each person claims that his paint color is a perfect match to what the railroad used, and don't use a different color.  Now you are even more confused than you were before.  But here's the catch:  They are all wrong.

First of all, let's take a look at how color works.  When you look at an object, the color you see is the color reflected off the object's surface.  If the object is blue, then all the other visible light wavelengths hit the object and are absorbed, but the specific wavelength for the color of that object is reflected back and that is the color you see.  However, there are factors that affect the way it appears.  Different colors of light can change the color of the object, as well as the angle the light hits the object and the angle that you view the object.  If you compare two photos of the same locomotive taken at the same time on different days, one sunny day and one cloudy day, the color of that locomotive will appear different in both photos because the color of the light hitting it is different.  If you compare the color of the different surfaces on the same locomotive, the colors will also appear different, because you are looking at them from different angles.

More specific to trains, there are other factors that affect the way a color looks to our eyes.  A locomotive that was repainted yesterday and a locomotive that has been out in the sun for 10 years will be different colors, even if they were painted from the same bucket of paint.  The sun fades the paint, making it look lighter over the years.  Dirt, rust, soot, and grime also affect the color of the locomotive, because no matter how hard you scrub the dirt off, there will always be some there.

Let's take a look at the models again.  Realistically, will anyone notice if the paint color you use is slightly different from the exact color the railroad used?  Yes, you say, but actually, even if you do track down the exact paint color, it will probably appear wrong if it were possible to notice such small differences.  What kind of lighting do you have in your train room?  How does it compare to outdoor lighting?  What angle do you view the trains on your layout?  How does it compare with watching real trains?  How long have your models been left out in the sun?  How much dirt has accumulated on them?  When you come right down to it, there is no such thing as an exact paint match, because even on the real railroad, two identical locomotives painted from the same paint bucket can appear different from each other.

Now I'll let you in on another secret.  When selecting a paint color for my fictional railroad, the Merrimack & Souhegan Railroad, I bought a can of dark blue spray paint at Walmart because it was cheap and I liked the color.  As it turns out, it is a good match for Pan Am Railways locomotives, and I have used it to paint one of their engines.  My friend John also uses the same Walmart spray can to model CSX and Baltimore & Ohio locomotives.  I haven't modeled any, but it could probably be used for Alaska Railroad blue and Santa Fe freight warbonnet blue.  The truth is, manufacturers don't want to buy unique paint colors for specific railroads, so they will reuse the same color on other railroads.  Just because the paint bottle is labeled "Reading Green" doesn't mean you can't use it for a different railroad, because in real life, someone probably did.  In fact, I use Reading Green for corrugated steel warehouses and wooden window frames.

What it comes down to is this:  The only perfect match you can get is among your own models.  If you use a specific paint color for one locomotive, use that same one on the next locomotive you paint.  Nobody, not even that guy from the historical society or the paint specialist, will notice the slight difference between your models and the real thing.  However, if you use slightly different paints on different models that are supposed to be identical, most people will notice that.  So don't fret about matching the paint on your models to the paint on the real thing, the biggest concern here is matching the paint on your models to the paint on your other models.

Tutorial: Cushioned Drawbars

Today I am sharing a video James and I made in July. James figured out a simple way to add working cushioned drawbars to model trains, and this video explains how. It is very easy to do, and adds that much realism to your freight cars. On the real trains, cushioned drawbars help to protect the load in the car by absorbing some of the impact during coupling, so the load doesn't move around as much. A lot of box cars and flat cars are equipped with these.

James and I hope to post videos more often, so be on the lookout for those! If you haven't already, you can subscribe to our YouTube channel and see videos there that we haven't posted here.

Anyways, my rant is over. Enjoy the video!

A Little Tour

Today being Wednesday, I would normally reserve this post for some stories from work.  However, nothing particularly unusual has happened at work this week, so I thought I would use this post for something else.

Steven and I have both made references to various model railroad ideas and equipment that we own, and we have even posted pictures in the past.  We have never really talked about any current projects though, which we thought might be interesting.  Usually both oh us have about a dozen things going on at one time, and the work bench is often more cluttered than makes sense, but I suppose that is probably not unique to either of us!

Below is a video clip I took today, it is about sixteen minutes long, and it is just a tour of my work bench.  I figured reading most of my posts takes as long as the video lasts.  In the video you will see some of my current projects, a finished project, and a small part of my equipment.  It is totally unscripted, just my thoughts as they occurred to me during filming.  Anyway, enjoy the switch from the normal programming.



As usual, if you have any questions about what you see, feel free to leave a comment.  You can also send us an email at ogden.bros.trains@gmail.com, or you can email me directly at james@ogdenbrotherstrains.com.  Next week, we will go back to our regular scheduled programming, probably.

Electronics Part 2: Model Railroading Applications

So now that I've thoroughly confused you last week, let's clear it up a little this week and talk about something more familiar: model trains. Specifically, what on earth does last week's post have to do with model trains? Well....

Let's look at something I've been working on recently. Most of my locomotives don't have working headlights, and I want to fix that. I want LED headlights because they look great, but I can't afford the prices that some of these manufacturers charge. Instead I found a website that sells LEDs and other electronics cheap, but they aren't marketed for a specific purpose. Because of that, the manufacturers can't know what the applied voltage will be on the consumer end, and can't make a resistor recommendation to the customers, meaning I need to figure out what resistor size to get on my own. The manufacturer does, however, say that the LEDs use 2 volts and draws 20 milliamps, or 0.02 amps.

Let's set up the problem. We have a few knowns: First, we know that the LED takes 2 volts. Second, we know that the applied voltage is 12 volts. Because of this, we know that we need a resistor in series with that LED, and we know this resistor must use up 10 volts. We also know that the LED draws 0.02 amps, and because this is a series circuit, we know the resistor and power source current values are also 0.02 amps. So the two things we need to know are the resistance value and power consumption of the resistor so we get the right size. Let's draw a diagram:

What we need to know are the two unknown resistor values, which is easy to figure out. To find resistance, simply divide voltage by current, or 10 volts divided by 0.02 amps. This gives us a resistance value of 500 ohms. To find power usage, multiply voltage and current together for a power value of 0.2 watts. You should never buy a lower value resistor than you need, so if the value you need isn't available, get the next higher value. I bought 510 ohm resistors rated at 1/2 watt just to be on the safe side, and they work fine.

This circuit is great for a single ditch light. You will need two of these circuits, wired on separate functions, for a flashing ditch light effect. I will not get into the programming in this series, but I will cover it at some point. However, my locomotives have two headlight bulbs, one just above the other, and I need an LED in each one. I could use two of these circuits wired to the same function, but I think it is easier to run both LEDs off the same resistor. However, this changes the resistor value, so let's take a look at that circuit.

This is called a series-parallel circuit, because the two LEDs will be in parallel with each other but both in series with one resistor. This complicates the math a bit. Let's identify our known values and fill in a diagram, and I will walk you through the math. First, we know the source voltage is 12 volts. We are using the same LEDs, so we know they use 2 volts and draw 0.02 amps each. They are in parallel with each other, so the voltage stays the same, so the resistor still has to use 10 volts. However, the current is additive in a parallel circuit, so now we have 0.04 amps going through the resistor instead of 0.02. Let's draw a diagram:

This problem looks more complicated, but it's actually just as simple as the last one once you sill in the knowns. We are looking for the same values as last time, the resistance and power ratings of the resistor, and we will find them the same way. Let's divide 10 volts by 0.04 amps. This gives us a resistance value of 250 ohms. Multiplying our voltage and current together gives us a power usage of 0.4 watts. Again, we will use the next higher available value, so in this case I bought 270 ohm resistors rated at 1/2 watt and they worked just fine.

One last thing on my headlight project. My fictional railroad, the Merrimack & Souhegan Railroad, is a short line based in southern New Hampshire. Because the branch lines do not have turning facilities, and the locals are run as turns and in most cases with a single locomotive, this means that most road switchers on my layout will have to run long hood first pretty regularly. This means that they need ditch lights on both ends of the locomotive. In real life this is a common practice in New England. However, since each ditch light needs its own function, that means I need four functions to run the ditch lights. Since I also need two functions to run the headlights, this means I need either a six function decoder, which is expensive, or a separate function-only decoder in addition to the motor decoder, which is also expensive. In both cases, I also have some advanced programming to do so that the correct ditch lights come on at the correct time. I am no master at programming and I don't have the money to spend on expensive decoders, so I sat down to figure out a way to use a regular four function decoder to run all these lights. And guess what? I did. I found a way to simplify programming, save space under the shell, and save money all at the same time by using technology that's been around about as long as electricity: the electromagnetic relay.

But that is next week's topic!

Electronics Part 1: Ohm's Law

Today I am starting a series on electronics which will likely go through the whole month. We are going to start with the basics, this week we are learning about Ohm's Law and how it works and how to make calculations based on it. Ohm's Law is the absolute most basic thing there is in electronics. Next week we will learn to apply Ohm's Law to modeling and learn about calculating LEDs and resistors. During this series, we will also discuss turnout motors, signals, switch logic, and basic DCC wiring.

Before we get into Ohm's Law, we need to define four types of measurements. These four terms will be used constantly, and it is important that you know what each one is.

Voltage, measured in volts (E), can be compared with water pressure in a pipe. It is not a measure of how much electricity there is, but the "pressure" behind it. In most model railroading applications, the voltage is 12 volts. However, some light bulbs and LEDs use much lower voltages, which we will discuss later.

Current, measured in amperes or amps (I), is a measure of how much electricity a circuit uses. One light bulb takes a certain amount of current to operate correctly. Two light bulbs use twice as much current. Again, we will discuss in more detail this later.

Resistance, measured in ohms (Ω or R), measures how much the circuit fights back. The circuit components are always trying to block the flow of electricity, and resistance is the measurement of the blocking. However, this is useful. Using a resistor, we can bring down the voltage to light an LED. There are more applications as well, which we will discuss later.

Power, measured in watts (W), is actually a measure of energy, not specifically electricity. Power is not actually defined in Ohm's Law, but it is another measurement that we will use. Unlike voltage and current, which can be changed, power is a direct measurement of how much energy a circuit uses based on what is on the circuit. Energy cannot be created or destroyed, only transformed.

Ohm's Law can be defined as "The current in a circuit is directly proportional to the applied voltage and inversely proportional to the circuit's resistance." So what does that mean? Well, let's break it down a bit: the law defines three things, the current, the voltage, and the resistance, and how they are related to each other. "directly proportional" indicates multiplication, and "inversely proportional" indicates division. Let's make a few equations based of this law:

E=IxR

I=E/R

R=E/I

We can also define how power is related to these other measurements:

P=ExI

Let's take a 60 watt light bulb and figure out what the resistance is and how much current it draws. We know two of the numbers, so let's start with that. We know the voltage is 120 volts and the power is 60 watts. By rearranging the P=ExI formula to solve for I, we get I=P/E. We know P and E, so let's divide 60/120. This gives us a current of 0.5 amps. Now that we know both voltage and current, we can find the resistance. By dividing voltage by current, or 120/0.5, we get a resistance of 240 ohms. There, just like that, we figured out a simple light bulb.

However, most circuits are a little more complicated than that. There is a good trick to remembering those formulas:

So what do these circles mean? Easy. The top half divides with one of the ones on the bottom to find the other one on the bottom. The bottom two multiply together to find the top one. So if you are looking for current (I) and know voltage (E) and resistance (R), the first circle tells you to divide voltage by resistance to find current. If you want voltage, multiply current and resistance together. If you want resistance, divide voltage by current. The second circle works the same way, and is used when you know or want to know the power. The formulas can be hard to remember, but the circles are easy. Just draw the circles on the top of your paper before solving the circuit.

Speaking of solving circuits, let's get started with that. Let's use another light bulb, how about a 100 watt bulb this time. This animation will walk you through the steps:

Simple enough, right? Wrong. That's just the basics. There are also series circuits, parallel circuits, and there's even circuits with both. Series and parallel circuits introduce some new rules in the math. Let's start with a series circuit.

In a series circuit, you have more than one device on the same line. That way, the electricity only has one path to get back to the power source: through both devices. Because of this, the voltage gets split between the two devices, and the current passes through both. So to solve a series circuit, here is how the measurements of the different devices interact with each other:

Voltage is additive. If one device uses 60 volts and the other uses 20 volts, the total voltage will be 80 volts.

Current stays the same. If the total current is 5 amps, it will be 5 amps at each device.

Resistance is additive, just like the voltage.

Power is additive, just like resistance and voltage.

Let's take a look at a strand of Christmas lights. You know, those annoying things that manage to tangle themselves every year? We all spend countless hours trying to figure out which one bulb is dead, because that one bulb shuts off the whole strand. This is because these bulbs are wired in series. There is only one path for the current to follow, and if one bulb is dead, the path is broken, or open. All the bulbs have to be working for the circuit to function, or close. Most of the math is the same as before, so rather than doing a whole diagram again, let's do a more simple problem.

Most Christmas light bulbs operate in 2.5 volts. We wire them in series because we plug them into a 120 volt wall outlet. Because voltage is additive in a series circuit, having enough of these 2.5 volt bulbs strung together in series will add up to 120 volts and we can safely plug the strand into a 120 volt source. So how many of these light bulbs have to be in series to go on a 120 volt source? Let's figure it out. This is a simple problem, all we really have to do is divide 120 by 2.5. That gives us 48. So in order to safely operate 2.5 volt light bulbs on a 120 volt source, you must have 48 of them in series with each other to use up the voltage. Current, however, works differently. There is only one path for the current to take, through each light bulb, so the same electricity in the first bulb lights up all 48 bulbs on the strand. In a series circuit, current stays the same everywhere on the circuit. Assuming a resistance of 8 ohms per bulb, which is a normal value for these bulbs, and multiplying that by 48 (remember resistance is also additive in a series circuit), we get 384 ohms. Now that we are talking about total resistance, we must divide the total voltage of 120 volts by 384 ohms to get our current of about 0.3 amps. Each bulb on the strand uses 0.3 amps, and the total usage of the whole strand is also 0.3 amps. Multiplying this by the voltage tells us that the whole strand uses a mere 37.5 watts.

Series circuits are easy. But we don't use them a lot. Parallel circuits are used more. This is when two or more devices are wired together so that there is a separate current path for each one. That way, when one goes out, the rest can stay lit. However, there is a new set of rules for this type of circuit, which is a little more complicated.

Voltage stays the same in a parallel circuit. If the source voltage is 120 volts, the voltage across each device will also be 120 volts.

Current is additive. If one device draws 3 amps and another device draws 5 amps, the total current will be 8 amps.

Power is also additive.

Resistance is where it gets complicated. Resistance can be calculated by the following formula:

Rt=(R1 x R2)/(R1+R2)

where Rt is total resistance, R1 refers to one resistor, and R2 refers to another. To simplify things a little, if all resistor values are the same, you can simply take the value of the resistors and divide that number by the total number of resistors in the circuit to get total resistance. You might be thinking, this doesn't make sense, the total resistance is lower than each resistor! Well, that's true. As more paths are created, it is easier for the electricity to get back to the source, and so the total resistance of the entire circuit is lower than any path individually. Remember also that current is inversely proportional to the resistance, so as the resistance goes down, current goes up, meaning the circuit uses more electricity with more available paths, which is normal.

Let's take a look at an easy parallel circuit. Again, I won't draw a diagram. We will look at more complicated circuits next week, and I will use diagrams then. But for today, let's do an easy one. Let's take two 100 watt light bulbs and put them in parallel with each other on a 120 volt source, and figure out what the total resistance and total power consumption will be. You can get around the hard math by using the total power (100w plus 100w is a total of 200w) and the source (total) voltage, but let's do it the hard way by using the resistance values of the bulbs. We know that the voltage at each bulb is 120 volts because it is a parallel circuit. We also know the power consumption at each bulb is 100 watts. If we divide 100 watts by 120 volts, we get about 0.83 amps at each bulb. Current is additive in a parallel circuit, so we now know that the total current is about 1.67 amps. The resistance of each bulb can be found by dividing voltage by current, or 120 divided by 0.83, which gives us about 144.58 ohms. Both light bulbs are the same, so both resistance values are the same, so we can simply take the resistance value and divide it by the number of bulbs, or 144.58 over 2, to get a total resistance of 72.29 ohms. We've already figured out our total current one way, but now that we have new numbers, let's check our math by dividing 120 volts by 72.29 ohms. This gives us a current value 1.66 amps, close enough when you consider that we rounded our decimal values during the problem.

Clear as mud? Well, that's all for this week. If you're confused, reread this a few times or make up some practice problems if you want. Next week we will cover more complicated circuits and apply what we learned this week to some common model railroading problems. I hope I haven't made you give up on electronics completely!