TCS
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...
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...
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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Decoder Wars I
Edit: see the comments for some additional notes; also, I’ve edited the text to correct some errors, but those edits are marked.
A long time ago, in a distant land, titans met to do battle...no, wait, I mean recently, on my kitchen table, I started testing DCC motor decoders for N-scale EMUs. And as with most wars, after it started I began wondering why on earth I’d thought it was a good idea. Still, I have reasons for this, and the result is important: the winning candidate will go in my (so far) 27 trains that don’t support Kato’s plug-in decoders, and some have two motor cars, so it’s closer to 30 decoders.
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A long time ago, in a distant land, titans met to do battle...no, wait, I mean recently, on my kitchen table, I started testing DCC motor decoders for N-scale EMUs. And as with most wars, after it started I began wondering why on earth I’d thought it was a good idea. Still, I have reasons for this, and the result is important: the winning candidate will go in my (so far) 27 trains that don’t support Kato’s plug-in decoders, and some have two motor cars, so it’s closer to 30 decoders.
Read More...
November 2012 Status
November, as you may have noticed from recent posts, went largely to laying the groundwork for installing wire-in DCC decoders, and a bit of testing of same. After a few delays, most of what I was waiting for finally arrived, although a few things are still backordered. In particular, the six-pin NEM651-compatible plugs and sockets mentioned in the comments last time have arrived. For the curious, the parts list has been added to my page on DCC Decoders. Read More...
Wired DCC Decoders I
This is the first of what I expect will be several posts about wire-in DCC decoders. Up to this point I’ve either been using the Digitrax-made Kato decoders that snap into Kato trains, or lightboard-replacement decoders for locomotives. But I have a large number of trains that don’t take either of those, many of them the commuter trains I’ll want to run on my new commuter line (once I finish the DCC wiring for that). Read More...
