Tag Archives: LEGO

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…

LEGO Contest – Mini Building Madness!

A few days ago, The LEGO Group announced a contest with a pretty amazing prize package.  Since model railroads are as much about scenery as they are about trains, I think many of our readers will be interested in this one.

From the announcement:

Today we’ve launched a new contest on LEGO Rebrick, one we’re only sharing with RLUG/RLFM members. To mark 10 years of Modular Buildings, we invite you to build a mini modular for a chance to win the grand prize of all modular buildings as well as the Mini Modulars! This includes:

• 10230 LEGO Mini Modulars
• 10182 LEGO Café Corner
• 10190 LEGO Market Street
• 10185 LEGO Green Grocer
• 101097 LEGO Fire Brigade
• 10211 LEGO Grand Emporium
• 10218 LEGO Pet Shop
• 10224 LEGO Town Hall
• 10232 Palace Cinema
• 10251 Brick Bank
• 10246 Detective’s Office
• 10243 Parisian Restaurant
• 10255 Assembly SquareWe will also have two runner-ups in this contest, who will win the 10255 Assembly Square.
For more information on how to enter. Including rules and size requirements, please visit:


The contest closes May 12th at 10:00 a.m. EST. Don’t forget to share this contest with your fellow RLUG/RLFM readers/subscribers/readers/subscribers!

Most exciting about this prize package, other than the sheer size of it, is the chance to win some pretty incredible retired sets.

– Brick Model Railroader is a Recognized LEGO Fan Media (RLFM) outlet.

Hybrid PF/9V Systems

Following up on my previous article introducing LEGO’s 9V system and their Power Functions (PF) system, I’m going to go a little more in depth about building hybrid systems that utilize both PF battery packs and 9V train track. I’ve developed and iterated through several different systems that combine the best of both and have come up with several easy to implement systems.  Anyone with a few dollars, a volt meter and a soldering iron can hack together one of these hybrids in a matter of hours. Continue reading Hybrid PF/9V Systems

Jersey Girl

Central Railroad of New Jersey 1940’s Commuter Train in LEGO

This is my LEGO model of a 1940’s Central Railroad of New Jersey commuter train. This train is typical of those that made up the CNJ’s short haul commuter service in the first half of the 20th century. You may have already seen the locomotive in my recent article on Vinyl Decals, or on a recent youtube livestream. Now that the locomotive is properly decaled, I finally took some time to photograph the whole train and write this article.

Full CNJ commuter train.

The seeds for building this train were planted several years ago while on a trip to visit Steamtown National Historic Site. While there one of the locomotives that caught my attention was an odd little Canadian National engine,  no. 47. Canadian National no. 47 is what is referred to as a “Suburban” locomotive.  These locomotives were built for short haul service on commuter lines. The Suburban type had its tender, carrying coal and water, integrated with the main frame of the locomotive, rather than having a separate “tender” car semi-permanently coupled to the locomotive. This gave the locomotive excellent dual directional capability, handy for when there were no provisions for turn the engine around at the end of it’s run. It was not uncommon to see these engines running backwards pulling their train on a return trip.

Continue reading Jersey Girl

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 L-Gauge.org. 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.

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

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.

Continue reading Decals For LEGO Trains: The Vinyl Option

The JJ Young, Jr Flickr Collection

2 weeks ago I  wrote about the Barriger Library and the wonderful historical resource it provides for North American railroading. Today I want to point out another great flickr library that myself and several of my fellow LEGO train builders have been drawing inspiration from. The JJ Young, Jr Library.

The John J. (JJ) Young, Jr. Railroad Photo Collection

CNR pacific #5588 is caught racing as speed with the engineer sounding the engines whistle....

Continue reading The JJ Young, Jr Flickr Collection

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…

Continue reading Building an European Railcar Part 2 – The Design

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?

Continue reading Building an European Railcar Part 1 – The Prototype