Tuesday, December 29, 2015

Building a Model Train Power Supply - Part 1

For a number of years I have owned a G Scale train set from Bachmann. Here is an example of the set:


If you have never seen a G Scale train set, it is quite large at a scale of 1:22.5. Another name for G Scale trains is Garden Railway. Unfortunately, I haven't had a workable power supply that would produce enough current to drive the train set. When I looked at buying a manufactured power supply from MRC, such as this:


The price of the power supply is around $260USD, holy crap! So that's out, time to build one I guess. After determining that the track voltage can get up to 21v and I would need at least 5 amps of current, I settled on using a power supply that I recently picked up from an electronics surplus store.

So, I start collecting some parts, and needed to get working on an enclosure. My plan was to have this power supply built by Christmas so that my kids can play with the train set for a few days before it & the Christmas tree go away for the season. Here are the parts that I collected for this project:


After taking some measurements, I decided to build a box that was 7 inches wide, 5 inches tall and 11 inches long. This should be enough space to fit all of the parts. I used Box Maker to get a drawing of the correctly sized parts that would be made with 1/4" plywood material cut in a laser cutter/engraver.

After measuring the electronic parts (power supply, buck converter, binding posts, voltage readout) I updated the Box Maker drawing to include holes for ventilation, knockouts and mounting screw holes.

Here is what the drawings look like prior to cutting. The top & bottom of the box:


The sides of the box:


That's it for now. In the next post, I'll go over the material I used for the box as well as finishing the plywood and assembly.

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