Feb 2013

A Clean Track is a Happy Track and February 2013 Monthly Status

Track gets dirty. Cleaning track is a nuisance. But if you want trains to run reliably, it’s an essential nuisance.

My layout is in an unfinished basement, with lots of boxes and other junk that collect a fine layer of dust, not to mention exposed joists with insulation, and power tools that kick up their own dust from cutting wood. A drop ceiling, drywall, and tile floor around the layout would be nice. But it’s not very practical in this basement. Maybe in a future basement...

So I clean. Often. Read More...

PWM Motor Control

DC motors are controlled by varying the voltage and polarity of the DC power connected to them. In a simple DC power-pack a rheostat is used to provide a voltage to the track that varies from zero volts to the power pack’s maximum, which is often around 16 Volts. A simple switch is used to swap the positive and negative outputs to change the polarity (and thus the direction the motor turns). This tends to waste a lot of power as heat, but since that’s happening inside the power pack (and “a lot” isn’t really all that much at these voltages) that’s acceptable.

DCC decoders need to take a constant-voltage AC input from the rails, and control a DC motor somehow. Even if they could use a rheostat, wasting power as heat inside a plastic model is more problematic. The technique normally used instead is called Pulse-Width Modulation, and it’s a fairly simple and commonplace, and efficient, method of controlling DC motors from a digital controller. The same technique is used in many other applications. Read More...

Computer Support

A computer is part of my model railroad. Why, and how do I use it? Well, the answer to the last question is “not very much”, so far, but I have plans. I recently had to re-do the monitor support attached to the layout, and I thought I’d discuss the reason it’s there, as well as the work on the support itself.
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Decoder Wars II - Lightboards

Comparing decoders for cab cars is actually relatively simple. These don’t need to do very much, so it’s really about checking basic functionality. I’ve laid out the full testing details on my Decoder Comparison Testing page, and here I’m going to summarize the findings for the capabilities of interest to me.
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