Category Archives: Building Techniques

Building Techniques and How To

Magnets and Electricity.. That’s a Power Couple

Today I’m bringing you some sweet new prototype technology from our good friends at 4DBrix. Tom Lowa was at Brickworld recently to show off something he’s been cooking up, and I have to say, it’s a pretty sweet idea. I’ve been emailing Tom about the concept and here is the information they gave me.

4DBrix has engineered a way to transmit power via the magnetic couplings on train cars. A short video is posted below:

It’s a pretty ingenious idea. For those that enjoy building passenger trains with detailed interiors (and lights) this is a great way to eliminate those ugly wires between the ends of cars. It also eliminates the need for bulky connectors between cars, which can be difficult to plug in and are also unsightly.

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Supercapacitor Power Packs

As an electrical engineer, I have always found lithium batteries to be…. amusing. They’re extremely volatile; if overcharged, they explode. If over-discharged, they explode. If charged too quickly, they explode. If discharged too quickly, they explode. If punctured, they explode. If they get too hot, they explode. If they get too cold, they simply don’t work. Think back to the recent debacle of the Samsung Galaxy Note 7 battery woes. But yet, these are the best batteries that are currently mass produced. Almost everyone carries one in their pocket and frequently holds it close to their face. For applications where the energy density (energy stored per volume) or the total energy stored (in Watt-hours) isn’t important, there is an alternative storage media that might be of interest to my fellow model train fans. Enter supercapacitors.

Not quite the same thing.

What follows isn’t for the electronically faint of heart. Accidentally short circuiting an alkaline battery or similar for a few seconds isn’t going to cause much harm. Short circuiting a bank of supercapacitors will melt wires and turn your supercapacitors into charcoal in no time. Be smart.

A supercapacitor is different than a battery in several important but sometimes subtle ways. For a model train, some of these differences are to our advantage, others are not. First off, when a battery is discharged from 100% to 0%, the voltage is fairly consistent. The difference between the full and empty voltages and the rate at which it falls depends on the type of battery. For example, a NiMh battery is about 1.45V full, and 1.2V empty. A capacitor is different; when empty, it is 0V. The “full” voltage is whatever you charge it to. Different capacitors have different maximum voltage ratings. When discharged, the voltage falls from the charge voltage to 0V. Most supercapacitors are rated for either 2.5V or 2.7V. Similar to batteries, putting multiple capacitors in series is how you get the desired voltage capacity. For example, a 9V system would need 4 2.5V/2.7V supercapacitors in series. When the system is charged up to 9V, the voltage will be split evenly with 2.25V each on the 4 capacitors.

The second major difference between the two technologies is the speed at which they can be charged. NiMh and LiPo batteries are usually limited to some fraction of their amp-hour capacity for their charge rate. Meaning, a 2000mAh NiMh battery can be safely charged at 1-2A. Of course, this varies based on manufacturer specs, and charging them faster will degrade their capacity faster, but that is neither here nor there. A supercapacitor has a much higher safe charge/discharge rate. The small ones I like to use in my locomotives are safe up to 3.3A! Much higher rated ones exist too, I built an experimental system that used 100F supercaps rated up to 35A. Additionally, a rechargeable battery typically is only rated for a few thousand charge cycles. A supercap can be charged several hundred thousand times.

The major downside to supercapacitors is energy density, or how much power you can store per volume. My choice supercaps are 4mWh/cm^3 whereas a 2000mAh NiMh battery is about 350mWh/cm^3. So they’re less dense by about a factor of 100, useless, right? No! If all we need to do is get over an unpowered track section, for example an unpowered ME Models R104 180 degree curve, we only need about 10 seconds of run time. So if we have an equal volume of supercaps to AA batteries, our run length will be 1/100th: an AA battery set lasts several hours, call it 2h on the conservative side. That means an equally sized supercap bank will run for 1.2 minutes, plenty of time for zipping through a short unpowered track section!

Some of the difficulty in implementing a supercap bank is limiting the charge current. From the perspective of your power supply, capacitors are more or less a 0 ohm short circuit which means the theoretical charge current will be infinite. You can limit this with a resistor, but realistically this is unfeasible. A resistor spec’ed correctly would have to be very physically large to allow for high heat dissipation. It’d get hot enough to melt LEGO (ask me how I know)! Additionally, as the capacitors charge, the charge rate slows down exponentially. Luckily, there are other methods available to limit the current. I found a cheap, small product on eBay that fits the bill perfectly: a CC/CV regulator. Not only can this thing limit the voltage to the bank, but it can also limit the current.

With a CC/CV regulator set to never charge past the supercap’s rated voltage and current, the next step is regulating the output of the supercaps. Because we don’t want our train to slow down as the supercap bank discharges, we need a DC/DC regulator. There are some nice cheap ones on eBay for about $1.50 that just so happen to be exactly 3 studs wide.

Above is my Amtrak B32-8WH being retrofitted with 10x 15F 2.7V supercaps. The small circuit board on the left is the CC/CV charger. The wires going down through the center lead to the fuel tank, which is where the DC-DC regulator, bridge rectifier, and bluetooth motor controller all live.
Complete circuit diagram of my supercap system. The bypass diode on the CC/CV charger was later removed.

I’ve also made a system with 10x 100F supercaps. The added capacity doesn’t really add any utility over 10F-20F supercaps, so all of my recent systems are 15F. One of the downsides to charging the supercaps as quickly as possible is the sizing of the power supply required to handle the peak current, especially when you have multiple locomotives on the same circuit. Luckily for me, my work has stacks of 24V 6.5A power supplies lying around. Unfortunately for you, they are not cheap new. A used PC power supply can be rigged up to perform similarly, but as always, the exercise is left to the reader…

Building a Steam Locomotive in LEGO Part 3 – Scale and Non-LEGO Elements

This is the third installment of a continuing series detailing my progress on modelling the Union Pacific’s 9000 class locomotive in LEGO.


Part 1

Part 2

In this installment, we will discuss the scale my model will use, and why I use it, as well as custom and aftermarket steam locomotive parts.

First, the issue of scale. Model train hobbyists tend to consider scale before anything else because, in general, scale is rigidly established for most model railroads. Most people are familiar with the common model railroad scales, such as HO, O or N. There are countless others,  but they generally have one thing in common – their scale is fixed based upon the track gauge. That is, the distance between the inside edges of the top of the rails. In the LEGO train world, that scale is not so rigidly fixed. LEGO never intended their trains to be part of a model railroad system, so they did not design their track and trains to be in the same scale. The first LEGO train system (not considering earlier wooden and plastic trains without a track system or power) was introduced in 1966. The rails were blue, and the ties white, but the gauge has remained the same in all subsequent LEGO train systems, roughly 38mm. between the inside of the rails. The locomotives and rolling stock were 6 studs wide, roughly 6 feet wide if we considered the rails to be standard gauge. That is obviously not a realistic scale for width but that does not make it somehow ‘wrong’ of course. Many locomotives in the real world are more like 11 feet in width, about 11 studs in LEGO in a strict track gauge equation. There are many excellent models out there in this scale, but it is not typical for a LEGO train layout, and it is not the scale we use in my club.

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Curved Track – What’s available, and what to Expect

I was recently contacted by a newer member of the LEGO Train community asking for information on the various types of curve tracks used in PennLUG. My response was a lengthy email, which has been adapted to fit an article format, and will be the content of this article.

Before I begin, I should briefly touch on some of the standards for LEGO track configurations. More information can be found on Michael Gale’s Standard spacing practices for most layouts (including my own PennLUG) use a 16-stud spacing between the centerlines of two parallel tracks. There are two main reasons for this standard. One, it was set by LEGO, when they produced the 9-volt switch tracks. Using a turnout, a return curve, and an extra length of straight track, you get two even and parallel tracks. Two, this yields a convenient way to build track: two lines evenly spaced on one baseplate.

Two parallel tracks and a standard LEGO turnout demonstrating the 16 stud centerline distance.
Every LEGO train enthusiast has probably, at some point, owned a loop of standard LEGO track. Any number of straight sections closed off by the small curve tracks you’d find in any 9-volt of Power Functions set. These tracks are known as “R40”,  as they have a radius of 40 studs.

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Decals For LEGO Trains: The Vinyl Option

In my first article in my series on decals for LEGO® trains, I covered some popular model RR manufacturer’s who make decals suitable for use with LEGO trains. This time I want to highlight one of the options for making your own custom decals for LEGO trains, vinyl decals. This is a newer option that I’ve come across but it offers some great possibilities.

The story of how Maci’s Monograms got side tracked into LEGO decals.

This all started some time ago when I came across a post on Facebook about some decals that LOLUG – Lincoln/Omaha LEGO User Group had made using cut vinyl. My friend and fellow train builder Nate Flood is a member of LOLUG and he quickly brought me up to speed on them. As it turns out, Nate’s daughter Maci is the one who produced the decals, and she has started her own business for the purpose.

When you order vinyl decals from Maci’s Monograms, you get the decals, a nice printed instruction sheet showing you how to apply them, and a little thank you note. It makes for a great presentation when you open the package. Locomotive NOT included.

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Building an European Railcar Part 2 – The Design

Last time, I spoke about how to start modeling a typical European style goods railcar. I have been speaking at length about all kind of fancy ways of making sure you understand your prototype. I hope you have been making notes because today we will immediately dive into the fun part: Building! Let’s just take off where we left now, shall we?

Step 4. Choosing your materials

After the scale has been set, it’s time to decide which part will be essential for your design. This might sound silly, but in my opinion every train model has 1 defining part (or technique, meaning several parts combined) around which the whole model is being build. In this case, I settled on the Lego Chair in brown, since I had a lot of them and wanted to get rid of them without selling. Also, the idea was that brown would nicely mimick the rust on the prototype (And trust me, some of them were far worse off than the one you just saw). Turning them into a railcar seemed to be the right solution. It didn’t work out as planned however…

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Building an European Railcar Part 1 – The Prototype

As I already said in an earlier post, I’m a big fan of railcars and I do believe they should get more attention. Locomotives are nice, but when they can’t haul a big rake of railcars, they just look silly, if you ask me. In the end, a locomotive is meant to pull railcars, not run around looking all nice and shiny.

However, I know it’s difficult to pull off a nice railcar, because in the end, they are all quite boring, definitely when it comes to goods railcars. By accident, I have been documenting my last railcar build pretty well, so I thought it could be interesting to share. This will be a three-parter with three easy topics: 1. The Prototype, 2. The Build and 3. The Bragging. However, let’s start at square one, OK?

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The Wonderfull 7-Wide World of Erik

Erik (Adult_Boy) should not be an unfamiliar name within the Lego Community. However, after having build quite a lot of Space and Sci-Fi themed stuff in the last years, he has now gone on a train-related building spree again. Most of what Erik builds is 7-wide, but he manages to very skillfully merge Lego’s own building style with a high level of details, closely mimicking the prototype he is recreating. However, I think it’s best if the models just speak for themselves:

Pere Marquette 1225 with Modified Troop Sleeper
M53, based on Baltimore & Ohio “wagontop” style boxcars
Make the town theme great again!
grain train

Want to know more about how Erik did this? Click!

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Battery Powered vs. Track Powered

Young and new recruits to the LEGO train scene will never have known anything other than the current generation of power functions. Battery packs coupled with infrared receivers and remote controls, each taking up precious space in your build. However, it didn’t used to be this way. The previous generation of trains (ignoring the aborted RC train theme) used metal rails to directly power the motors. Both generations had their own advantages and disadvantages, which I will attempt to shed some light on. In a follow up article, I will go over some advanced applications of each, and hybrids that combine the best of both technologies.

Batteries take up space. In my eye, this is Power Function’s main drawback. Additionally, the current generation Infrared (IR) Receiver is quite large and the sensor on it needs to be visible from outside the locomotive for the signal to reach it.

IR Receiver with the shell removed. Why is this thing so big?

Trying to incorporate the AAA/AA battery pack and the IR Receiver into a model is often very tricky, especially when working with 6 or 7 stud wide models. Additionally, batteries need to be recharged or replaced after several hours, so the battery pack needs to be accessible or removable.  When running for many consecutive hours at a convention, swapping batteries becomes a chore. For home use, it is not such a big deal. The IR receiver also has difficulty reaching more than a few feet when there aren’t any walls or ceiling to reflect the light off of. On the other hand, the IR receiver and battery boxes are still currently in production, which means they’re cheap.

PF track Vs. 9V track

Track power has always been my preference and I’ve iterated through several generations of electrical systems searching for the best configuration. LEGO’s classic 9V train controller is simple, turn the knob and your locomotive starts to move. The biggest limiting factors are being limited to metal equipped track and the original 9V train motor, (meaning no double crossovers). Additionally, laying out certain track geometries will cause short circuits. Also, once your loop gets to a certain length, additional power hookups are required so as to avoid slow downs. Of course, the main drawback is price. Expanding or building a new 9V layout is very costly. 9V straight track hasn’t been manufactured in almost 10 years and averages $3.50 each used and $5.50 new on the aftermarket. Original 9V train motors average $35 each used and $75 new.  Many clubs still use 9V systems, and with ME Models finally shipping their metal track, will continue to do so for years to come.

Things start to get interesting when you get rid of LEGO’s speed controller and start substituting your own electronics. Swap in the third party Bluetooth controlled SBrick in lieu of the IR receiver and not only save space, but also gain control range, gain 2 more channels for a total of 4, and lose the line of sight requirement.

In addition to being gigantic, the output power per channel is low.
2 Channel PF IR Receiver3rd party SBrick, approx 8x available power output in a smaller footprint


Get rid of the LEGO 9V train controller and use constant track power to feed a Bluetooth motor controller. No batteries! Or better yet, use batteries and track power together: constant track power feeding a Bluetooth motor controller, with batteries for backup. With such a system, a track powered locomotive can continue through double crossovers, over draw bridges, maintain consistent speeds through spotty connections on dirty track, or possibly even charge itself. With the track providing power most of the time, the batteries will rarely need to be recharged.

Read about my experiments in hybrid systems in depth in my next article.

The Union Pacific Type – Building a Steam Locomotive in LEGO

This will be the first in a series of articles about my process of building a LEGO steam locomotive. I intend to cover a variety of topics in this series including research, the use of custom elements, aftermarket electrical devices, and building techniques. While I will focus on a specific locomotive project I am currently working on, this series will not include a full set of step-by-step instructions to that locomotive. My intention is to share some experiences and techniques that I hope people can apply to any steam locomotive project, and perhaps other types of LEGO models as well. At any rate, my designs are usually pretty fragile and don’t really lend themselves to redistribution via instructions. Instead, I will lay out my approach to building a steam locomotive and why I think it is effective. I hope that this will help people who are struggling with what I think is a particularly difficult type of model to build or, at least, be of some interest to the readers of this site.

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