Apr 2013

Detecting Trains with IR Sensors, Part I

In my continuing work on the Arduino-based Tram Controller, I’m now playing around with the part I really wanted to work with, the Infra-red optical sensors themselves. This turned out to be rather more complex than I’d anticipated, but I’m most of the way there, even if I don’t quite have the system working yet. This is a post about what I’ve done so far, and what I’ve learned, with a bit about what remains to be done.

Arduino CPUs and Motor Shields

I’m still playing with Arduinos this week, but the little beasties are multiplying. That’s partly because I want to be able to test with the various CPU architectures, but also because each has unique strengths and weaknesses, and I’m still evaluating which of them is going to be the right choice for my tram controller. At the same time, it turns out that there are a number of options for motor shields, as I mentioned last time, and they too have strengths and weaknesses.

Revisiting Arduino

Two years ago I wrote about my plans to use an Arduino to control a pair of trams on a double-track line sharing single-track stations at each end, replicating the design of the Tōkyū Setagaya line. That’s briefly written up in that earlier post, and I also have a full page about the project that goes into more detail, with a sub-page about the current testing work.

Back then I bought an Arduino Mega 2560 and a bunch of other parts including a “shield” used to drive DC motors, loaded the basic test program that blinks a LED into it just to convince myself I could do it and the hardware worked, and then put it on a shelf for “later”. And forgot all about it while I worked on other things, only infrequently looking at the empty tram tracks and thinking “I really should figure out how to make that work.” It’s not like I dislike the work: I enjoy both programming and soldering simple circuits together. I just never could work myself up to starting what I expected to be a fairly major project. It was always: “I’ll work on that after I finish project ‘X’”, but there was always another “X” to occupy me.

Bus Models for Japan

Jerry’s recent post on Quintopia about cars and the arrival of my order for four N-scale Tomytec bus models have me thinking about road vehicles.

One of the hardest parts of modeling a contemporary model railroad is the lack of contemporary road vehicles. By far the majority of what is available seem to be things not seen on roadways for half a century. And an urban railroad needs a LOT of model vehicles to look even slightly realistic. And they can’t all look exactly alike either.

As Jerry noted, Tomytec’s collections of cars, trucks, and busses (links are to Japanese pages) are a very good way of acquiring fairly detailed models in bulk at reasonable costs. A typical car collection bought from Japan runs US$67 before shipping and contains twelve boxes, each containing (typically) two vehicles. Even with shipping, that’s likely less than $5 per vehicle. Not as cheap as the low-quality Chinese models available off Ebay, which are suitable for filling in back streets, parking garages, and other places where the car is more glimpsed than seen. But a good price for a detailed model, and about a third of what European models go for.

Shipping from Japan isn’t cheap. I use EMS (express mail), and shipping my order of four busses cost me $15, about 50% of the cost of the busses themselves. But I’m impatient, and EMS gets the package to me in about five days. If you can wait weeks (or sometimes months), shipping SAL (standby air) will be a lot cheaper for small, lightweight, models like these. But it’s still going to be a significant part of the total cost. If you want to order these, see the websites of the Japan-based hobby stores listed on my Suppliers page for more specific information.