Since I installed the Sabertooth 2x32 motor driver module in my Accucraft GP40, I have been thinking about the option of using a model aircraft style RC unit. However, investigations into the available RC systems revealed complications of using a joystick style controller for forward/reverse control, lights and horn.
Some people on YouTube have used car-type RC units which had a trigger control for speed and forward/reverse, but these seemed more suited to rapid changes of speed and direction rather than smooth control of a train.
I was mainly thinking of using the remote control mode for shunting to avoid getting on and off the train for uncoupling/coupling. It will also allow the loco to be easily driven “light engine” without a driving wagon attached, such as for running around a train.
Then, I hit on the idea of using a push-button remote control similar to what I have been using for points. These use relays which can be programmed for momentary or latched operation, latched being best for points control.
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| Typical 4-channel Remote Control from eBay |
By using the momentary mode, I could assign the 4 buttons for speed increase and decrease, forward/reverse (toggle) and horn. Using a Picaxe microcontroller, I programmed appropriate actions for each of the push buttons, included a degree of “inertia” to avoid sudden movements. The microcontroller outputs a 0-5 V speed control signal, as well as 12 V on/off outputs for forward, reverse, and horn. The electrical interface is compatible with the Mini Train Systems control panel, even though that is not required when using the push button system.
Over the last 2 days, I have made a “proof of concept” model which I was able to test this morning, and it works quite well. Some features include:
- Button A operates the horn
- Buttons and B and D increase and decrease speed with 16 steps.
- Button C toggles between forward and reverse. A short horn toot confirms forwards, two toots for reverse. The forward/reverse control is disabled unless the loco is stopped.
- There is a deadman timer which brings the train slowly to a stop after about 30 seconds of no button activity. Button C can be used to reset the timer if desired when the train is in motion.
- Configurable speed limit, currently set to 50% of max speed.
I have a 6-button remote control on order (about $50 on eBay). I plan to use the extra buttons for a rapid (emergency) stop and headlight.
I made a video of testing this morning. When the loco stops at 1:50 in the video, that is due to the deadman timer as no buttons have been activated for approx. 30 seconds.
In the photo below, the remote control receiver (with 4 relays) is on the right and the Picaxe microcontroller is on the left with stacked prototype board on top. The 15-pin connector and cable on the left connect to the loco's MU socket, and supply 12 V DC power to the Picaxe and receiver modules.
