Tools v. Toys


I’ve been wanting a Baldwin Centipede in N scale for 30 years, and finally, there’s one coming out soon. I had the money in my hands, but let the opportunity slip past. I bought an oscilloscope instead.

I’ll be frank: very few model railroaders have need of an oscilloscope. For most of us, a cheap multimeter is all the electrical test equipment we’ll ever need. Harbor Freight sells a digital one for a few bucks that provides the necessary functions. The little analog meter I bought at Radio Shack in 1987 travels with me to every train show. I have a larger Simpson meter on my workbench, and a big ol’ Heathkit job buried somewhere. Any one of these can measure voltage and resistance, and the better ones can measure enough milliamps to check on an N scale locomotive. So why’d I get such an extravagant piece of test gear?

I’ve been building DC throttles for a while now, and that pursuit has taken me into the realm of Digital Command Control hardware. I’m feeling the need to understand waveforms, how they’re generated and shaped, and how they behave, and nothing shows a waveform like a scope. Instead of regarding it as an expensive hobby item, I’m considering it a cheap education.

I took down the library exhibit a few weeks ago. While it was up, I managed to finesse the glitch in the throttle, but not eliminate it. I’ve been reluctant to post details on the circuit before that mystery is solved. I set up some T-Trak modules this weekend, connected the throttle, and attached the scope in an attempt to find out what was going on. The scope did reveal that the 5V rail on the Arduino Pro was dropping out for about 10 milliseconds, which would certainly cause the board to reset itself. Before I could probe much further, however, I poked the Arduino the wrong way with a capacitor, and killed it. (When attached to my trusty Arduino Uno, however, the throttle worked just fine. Watch this space for further details on it.) I still have a lot of learning to do.

This hobby is more than a leisure activity to me. It’s also an avenue of exploration.