Boulder Creek Engineering speedometer

"Roll-by" Bluetooth speedometer/odometer
Kevin Strong
“Roll-by” Bluetooth speedometer/odometer
Boulder Creek Engineering
2525 Arapahoe Ave., Suite E4-605
Boulder CO 80302
Price: $99.95

Bluetooth speedometer detector with 31mm wheelset; for use with Android or iOS tablets and phones; apps are free to download

Pros: Easy installation; phone/tablet interface is user friendly; customizable to your specific scale; accurate in all scales

Cons: None
Engineers used to gauge the speed of their locomotives by timing how long it took to go from one telegraph pole to the next. Poles were spaced a set distance apart, so engineers knew that, if they passed X number of telegraph poles in 10 seconds, they were going Y miles per hour. Most of us don’t have telegraph poles on our railroads, so how do we know how fast our trains are going? What’s needed is some kind of speedometer for our trains.

Boulder Creek Engineering has developed a speedometer that works with your smartphone or tablet. Their system consists of three components: the speed-detector circuit, a wheelset with a magnetic ring on the axle, and a downloadable app for your phone/tablet. They offer wheelsets in gauges from N to 1 (45mm).

Boulder Creek recommends first downloading the app to your phone or tablet to make sure it works with your operating system. It’s free from Apple’s App Store or Google Play. The software won’t fully function without receiving a valid Bluetooth signal from the speed-detector circuit, but it will launch on your device, which is sufficient to show that it will work.  

Once you’ve confirmed that the app works and you’ve received your speedometer and wheelset, you can install it. The circuit board itself is a small rectangle with a lithium button battery in the center to power the board. A two-pin plug with a jumper on it is used to turn the power on and off. Put the jumper over the two pins to turn it on; remove it to turn it off. For a permanent installation, you could wire in an external switch.

The circuit board itself has two ends—one with blue shrinkwrap, one with white. The white end is the business end, and needs to be mounted over the axle with the magnet on it. It’s a powerful magnet, so you can mount the circuit board on top of the floor of the car without worry. Just make sure there is no steel between the circuit board and the magnet to interfere with the operation.

The wheelset with the magnet on it replaces any wheelset on the car into which you’re installing it. Boulder Creek provides Bachmann’s 31mm wheels. These are close in diameter to many commercial wheels used in large scale, so even if there’s a slight difference in diameter, it will likely not be that noticeable. (You can always replace the other axles with Bachmann wheels to keep things even.)

With everything installed and the power turned on, you can start the app on your phone. It will read the signal from the speed detector. Once the link is established, you need to tell the software the scale of your train and the scale wheel diameter. For example, in 1:20.3 scale, a 31mm wheel is 24". If you’re running 1:29 scale, that same 31mm wheel works out to 35". Once you’ve done that, you’re ready to roll. The software can track multiple speedometers, and you can assign a photo to each one.

The speedometer will display speeds from 3 to 200 mph; if your locomotive is crawling along below a scale 3 mph, the display will read 0. There are a few seconds delay between a change in your throttle setting and seeing that change reflected on your phone. Speed is measured quite accurately; I double-checked it against a yardstick and stopwatch.

The software has an odometer feature as well. This works in two modes—real distance and scale distance. Real distance reads the distance traveled in 1:1 measurements. This feature can tell you how much track you actually have on your railroad. In scale-distance mode, it translates the 1:1 measurements to scale miles.

I had a lot of fun geeking out with this. It was interesting to run it behind different locomotives to see just how fast I had them programmed to run at “full throttle.” As expected, my small switchers were programmed to run slower than my road engines, but some of them ran slower than I thought they did. I can see myself using this device to reprogram the speed curves on my locomotives so they all run more prototypically. I had a lot of fun with the odometer feature, measuring the real distance between towns on my railroad. I discovered that a complete round trip on my line is a few feet shy of a scale mile. I also used this feature to calibrate the deceleration momentum and prototypical braking features of my locomotives, so I can get more predictable stopping times when switching. Best of all, the next time somebody asks me “how fast can it go?,” I can tell them precisely. 


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