Michael and I will both be traveling to spend the holidays with our families, so shipping may be slightly delayed. We wish all of you a merry Christmas with your families as well!
This is very much a “because I could” project, so keep that in mind… I built the SDX-1 soon after it appeared in Model Railroader in 1991. It served its purpose, both on my home layout and at several NTrak layouts with which I was involved. However, it has sat dormant for many years. A few months ago, I started to wonder what it would take to DCC enable it (it was originally intended to be used with DC throttles). So, with an Arduino and a little code, I now have a sound system that can make an N-scale diesel shake the room (literally!).
Keep in mind that the sound on the recording doesn’t do justice to the low frequency components. It’s much better to hear (and feel) in person. And yes, there are many other ways (maybe even more practical) to do this. This, however, was intended more as a fun application and test of the DCC Arduino Decoder Shield than any practical application.
As for the equipment seen in the video, from left to right, there is the SDX-1, an Arduino + DCC shield, a very crude level-shifting PWM DAC (i.e. a single transistor), and the Lenz DCC base station. The SDX-1 is driving the speaker itself (out of view below, sitting on the floor).
MRGui is our configuration utility for MRBus based devices. It simplifies the process of setting the various EEPROM configuration options for each node, using a user-friendly GUI that runs on Windows, Mac, or Linux. In addition to setting EEPROM configuration options, MRGui can also be used for general purpose programming of AVR microcontrollers. The instructions below take you through the steps to get up and running with MRGui on a Windows platform.
Time Locks – An Introduction
In the real world, manual switches within signalled territory are protected by devices called “time locks”. The purpose of these is to prevent a switch from being opened in the face of an approaching train. When the conductor wants to open the switch, he unlocks it and starts the timer running (how this is done depends on the model of time lock). The time delay gives any train too close to stop – or sometimes too close to even see a restricting signal – time to safely pass over the switch before the points are changed. It also triggers the signal system to display restricting aspects around the block, so trains that are further out are alerted to the presence of an open switch.
Once a programmed amount of time has passed, the timer indicates to the user that it has expired (often by a white or green light) and then releases a locking mechanism that allows the points to be moved manually. (This is commonly done with a locking pin through the throwbar that is retracted, but there are other mechanisms.)
Time locks aren’t just a good idea – they’re required by law here in the US. Under 49 CFR 236.207, either approach or time locking is required of manual switches in signalled territory.
The idea of a clock that runs faster than real time to compensate for the compression in our model world is nothing new. The idea has been with us since at least the 1960s. It provides a way to schedule our operating sessions, providing a sense of real time passage and urgency without needing literally thousands of feet of track to represent the vast distances covered by our prototype railroads. Aside from being a display on the wall, guiding operators’ train movements, fast clocks have remained an isolated system, our model world unaffected by the passage of scale time. Think about all the things in our daily lives that are linked to the time of day and you’ll quickly realize how odd that is given all our other technological advancements, and how much potential is in that idea. I believe fast clock integration is one of the huge, unexplored areas left in the hobby today for added realism.
In this article, we’ll show you how to build an inexpensive device that allows you to synchronize items on your layout to fast clocks by using MRBus, the networking protocol that connects the Iowa Scaled Engineering Networked Fast Clocks, in conjunction with the popular Arduino prototyping environment.
While DCC is primarily meant to power and communicate with the trains on the tracks, there are circumstances where having some auxiliary power available would be nice without having to run an extra set of wires. Maybe powering a remote turnout, an IR sensor, some animation or building lighting, or a fast clock secondary display?
We have been using the gEDA suite of schematic capture and PCB tools for a while now. Over that time, we have created a library of parts that have been successfully used in various designs. These symbols and footprints are now available via GitHub.
The ARD-LTC2499 was designed from the beginning with the intent to get as close to perfect accuracy as one could with an out-of-the-box Arduino Shield, while still keeping the cost affordable for mere mortals like us. We chose one of the best 16-channel ADCs on the market and matched it up with a high-performance voltage reference. To see what the accuracy really was, I borrowed Nathan’s 34401A meter and put them both to the test.
Have you ever been in the middle of an operating session and disaster strikes? A train derails, shorting out the DCC system, taking with it a power district, or even the entire layout. The problem is eventually fixed, but in the 5 minutes it took to restore things to the way they were, your fast clock kept ticking away. With a 3:1 ratio, all trains are now suddenly 15 minutes late.
Wouldn’t it be nice to simply press a button on the fast clock to pause time, then with a single press, restart the time right where it left off?
One of the most interesting electronic parts to come on the market lately is Berrett Hill’s Touch Toggles. They’re little electronic switches that operate by the proximity of your finger. There’s no mechanical movement, so you can put them behind acrylic control panel faceplates and other such and still operate them just by touching the surface. Unlike a mechanical switch, they never wear out, and they come with built-in indicator lights. Continue reading