I did it! You can too. I converted my model railway to DCC for around $20 (not including locomotive).
How? An Arduino, a motor shield, and a program called JMRI (Java Model Railroad Interface). I wish I could take credit for literally anything about this, but I can't, other than spreading the word. This was by far the most enjoyable investment I have made for my layout.
Let me start out by saying, this system isn't for everyone. It does not put out a lot of power (there are a few modified versions that do) so you cannot run a very large layout on it and you also cannot run a bunch of locomotives and/or accessories all at once. Sorry. Output is just over 2A, which should easily support 2 N or HO scale engines, possibly up to 4 if they are very efficient. With enough power drops and feeders, it should support a layout 30' long (with the base station roughly centered, 15' on each side). All that said, my layout is 2x4' and I currently only have 1 locomotive, and when watching my current draw, it rarely reaches even 10%, with the locomotive running at reasonable speed. Next winter I should be able to put it to more of a test, since my basement should be cleared out and I'll be building a larger layout (about a 25' long L shape).
Here is a video - turn the sound up to hear that diesel (it's pretty quiet in the video)
Here is the video I used to make my Arduino:
https://youtu.be/5Z9Kwjp8RuQ
And here is a video about JMRI:
https://youtu.be/xYZ9TMrMnqk
Also wanted to say, that even if you're going to stick with DC, you can use JMRI to do some pretty cool stuff- it can create manifests and switch lists for your trains, and keep track of where your cars are. It adds a fun aspect to operations and gives you "work" to do. You can do some pretty advanced stuff in the program- want an empty Canadian National box car dropped at your loading docks on Wednesday by an eastbound train and picked up on Friday to head west? You can set that up. Just want to add some randomness to your ops sessions? You can do that too. It takes a while to get used to how to make it all work, but with some fiddling, it becomes even more fun. My recommendation is to start off as basic as possible, get the locations created and slowly add more detail as you go along and get more familiar.
