Sunday, August 26, 2018

Portable PowerCab and JMRI Programming station

The Greenly Northern, my office layout, so far had a Raspberry Pi3 hardwired to the layout along with my NCE PowerCab. I described how I set that up in a post last fall. I wanted the layout control to be more portable and more flexible. E.g. take home the layout box, Pi with JMRI, and PowerCab over the weekend for comfortable programming at the work bench. Or maybe in the future take it to a show easily.

I decided that the occupancy sensors and the detector board are part of the layout. However, the NCE PowerCab track connection and the USB interface, as well as the Raspberry Pi need to be easy to transport. While at it, I also wanted a portable screen for the Pi.

At first I planned to pack everything into the same small tool case I use for the Mobile Station, and quickly realized that screen and electronics would fit, but the power supplies would not, so I decided to go for a larger aluminum case. The build quality of the case I chose doesn't come close to the black aluminum case at Harbor Freight, so I recommend getting that one instead. By the way, the only aluminum on these cases is the edge decoration.

The screen is a 10.1" TFT security monitor with 1280x800 resolution found on Amazon. I wanted a small and light-weight screen with high resolution and HDMI input. I added a compact, slim keyboard and a mouse, too.
Placement of the components was pretty straightforward. The screen is installed into the case lid using the standard VESA mounting holes. You can see the screw heads in the photo at the top of this post. The Raspberry Pi3 case clips behind one of the two metal brackets that normally keep the tool mat in place. I used a 1.5ft slim HDMI cable between Pi and screen, and a 3ft USB A/B cable for the NCE USB interface. All cables are secured with cable wraps or cable ties so that they are not caught in the gap at the case lid hinge.
The power supplies are plugged into a switched low-profile power strip with a short 3ft cord, so that I don't waste much space on cord storage when the case is closed. I used double-sided tape to hold the power strip into the case.

The NCE track interface for the PowerCab and the USB interface are mounted on some scrap hardboard away from other components so that the naked PC boards don't touch anything. I'm using a RCA socket mounted into the case side for the layout connection. This works just fine for low-amperage applications like the one I have here. The Raspberry Pi3 is plenty fast for decoder programming with JMRI, or controlling some automatically running trains.

With all parts in the case there's still enough space for a few N-scale cars and locomotives, some track, or other supplies.

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