Hacking a Better Throttle: Customizing DC Control for My Layout

Just give up control to the ones that know. Just give up control, let the whistle blow. Just give up control to the ones that know. And don't worry where the train will go. So this is the story about how a very very straightforward project to simply have handheld throttles turned into something far more complicated and a bit of a passion project. All I wanted to do was see if I could add some handheld throttles to my layout to control my trains. But like a lot of the things that I tried this one got a lot more involved I have always run DC. It is simple, it's reliable and it's affordable. So my layout is about 28 feet long. It's L-shaped and goes around the two sides of this room and at its deepest points is about 4 feet deep. And so for someone who's tethered themselves to DC in the short to medium term a stationary throttle just wasn't going to cut it. What I really wanted to do was stick to my DC layout but really enjoy the mobility that a standard DCC unit has. And to be clear I've wired this entire layout so I can convert it to DCC later but for the time being DC. So with that in mind I went looking for a DC product that would mimic the DCC solution. I came across an affordable small electronics kit called a Veripulse throttle and I was excited because it was in kit 4. So I sat at my workbench, put the first one together in about an hour, gave it a quick test and I was immediately impressed. The throttle is very straightforward. It just has a simple directional switch and a speed control and inside the unit you can make two minor adjustments to either the start voltage as well as you can add momentum. So as said I set it up, I gave it a try and it performed beautifully. Slow creeping starts with built-in momentum. I was immediately sold and so the following week I assembled an additional unit on one of my live streams and at this point I thought the project is finished. So DCC has been around for years. This is not a new thing but at same time DC hasn't gone anywhere either. For DC there is two different types. There's the old school variable voltage DC and there's the new pulse width modulation DC. With PWM the throttle isn't adjusting the amount of voltage. It's delivering full voltage in short pulses. The longer the pulse is on the faster the train goes. The shorter the pulse the slower it goes. It is a smart efficient way to control speed but it is not perfect. So I had tested the throttle. It worked great. I went back to laying track and I didn't revisit the project for a couple other weeks. So then what happened was I started unpacking all of my equipment and putting them on the layout and test running them and it was pretty obvious that some of the engines had a very noticeable hum. So I did a little bit of research and the best guess I could come up with was that it was the throttle's PWM that was causing a problem. PWM pulses create sharp edged waveforms. Some motors with iron core designs or sensitive internal electronics may vibrate at the frequency of those pulses and those vibrations become an audible hum. Your standard MRC controller also uses pulse width modulation but they have a whole series of smoothing components built in so you don't get that same result. The handheld throttle kits that I bought use unfiltered PWM. So I was in search of a solution and one of the suggestions that I read about was introducing what we'll call a capacitor array. Capacitor array bridges the track power in attempt to smooth the signals but at the same time not completely eliminate the low speed control. So I built a whole series of capacitor arrays and tested a whole bunch of different values going from one microfarad all the way up to 4700 microfarads and this is what I discovered. High capacitance, very smooth running, no engine hum but lurching on the startup basically from no speed to medium speed. Very low capacitance, smooth, some hum but much lower operating speeds. And so I weighed all the pros and the cons and I finally settled on using a one microfarad capacitor to allow for slow speed control and reduce the majority of the engine hum. A capacitor resists changes in voltage so when a pulse signal spikes the capacitor absorbs some of that waveform and flattens it out and that makes the signal a little closer to let's say pure DC what you're getting out of the original old school controllers. The side effect of that is it reduces the sharp edge of the signal but that also reduces the low speed control so too much capacitance the engine just lurches into action too low a capacitance and the hum returns to the motor. So over the next few weeks I continued to evaluate the modifications I had made and what I thought about them and ultimately I was really happy. In terms of form factor the throttles are amazing they're on 10 foot tethers and so I can move back and forth across the layout and watch the trains close up exactly as I want to. The low speed control is a little less than it was than the original but I've all but reduced 99% of the engine hum and that is a very worthwhile trade-off for me. Having decided that I was now settled on using these throttles I made some additional modifications to the handsets. The first thing I did was added four pin aviation plugs to the tether wires so that I had a little bit of flexibility and it was easier to disconnect. I also added some 24 volt LED lamps to the throttle unit so I could tell when they were powered up and I used two different colors so I could distinguish my westbound and eastbound throttles. Of course I needed to add branding for the faceless corporation that controls this entire area, Yuzon Industries, so what I did was I actually laser etched all of the branding and controls and logos onto the physical cases from the original kit. I set them up in my laser and I pre-registered it and then just did a quick etching. I replaced all of the knobs to give it a more industrial weathered feel and my last step was to give it a layout appropriate paint job. A quick coat of brown primer, an industrial school bus yellow top coat and then a combination of browns and rust colored paints to give it a distressed rusty feel with a slight dry brush of metallics to make it like it's been worn out in someone's hand over the ages. I wanted it to feel like it had been left on the warehouse floor for years and you've just come across it and picked it up and wondering what does this control? So this started simple, just a pair of handheld throttles but it has ultimately turned into a deep exploration of control performance and aesthetics. Now I have something that actually works and it actually looks like it belongs here. It wasn't the project I expected but I'm happy it turned out the way that it did. Thanks for tuning in and joining me on this journey and I'll see you next time. just give up control let the whistle blow just give up control to the ones that know and don't worry where the train will go