OK I reworked the schematic and now there are 5 relay boards, 4 rotary switches and nothing will let out the magic smoke. I will post pics of the components here soon, prolly tomorrow, I need to make some panels for the switches and indicator LEDs to print out for the unit, I will also be working on that here soon too.
So I just couldn't leave well enough alone tonight. I was thinking about the indicator panel as mentioned above and decided that the best way to do it was to make a PCB with the LEDs and mount that behind the 3D printed face plate. Well that's easy enough for me to do so I did it. At least the PCB part is done, I will wait until they arrive to get the dimensions to build the face plate. I may even make a board for the rotary switch, if I can find the correct part pinout to build the board with. Anyway, here is the indicator panel. This is the back side, so everything will be "backwards" on the control panel.
Ok, I finally got a few more parts in. I still need one more of the decoders but I have enough of them right now to get started with what I need. So that being said, here is a look at the parts, and how things are going to be started. Here are the G scale 5amp decoders from Digitrax. I have 3 of the 4 needed so here soon I will be ordering the last one. These are going to be used to “simulate” DC on the rails instead of using a standard throttle, or one like the Aristocraft Wireless. This will allow someone to use their phone, or a Digitrax wireless throttle. This is the relay board. I need 5 of these to get the job done, which isn’t a problem. The relay will not allow a line to be powered unless it is selected, and yes more than one line can have the same input. I don’t think that will be an issue, and I don’t feel like making a logic gate array to prevent it so… This is the power supply that will power the relay board, and the indicator LEDs, 2 amps at 5v should be more than plenty. And the last item up for Show And Tell tonight is my choice for selector switch. These are rotary switches 2P5T in nature and will handle both the LED switching and the relay switching. The command station, PM42 and UR93 will be shown later, you all know what they do. Now I mentioned in the first post that the PM42 will have some unique wiring. Well, I got blasted by this a while back on another model railroader forum (not naming any names, but some may figure it out) when a new person asked about the PM42 and how can it be wired. I mentioned it can have anywhere from 1 to 4 input sources, and the 4 outputs can be either power management or auto reversing and any combination of. Well that didn’t sit with some as I was summarily informed that it would be stupid to have 4 different inputs, why would anyone want to do that, and that the PM42 can ONLY do power management or reversing but not at the same time. Hmm… that’s funny because my (at the time) layout was using a PM42 to do both and it was working just fine, in fact that same PM42 had been used in a couple different layouts with the same results. I figured out that a PM42 just can’t auto reverse inside its own power district. Ok. But that’s not what I am doing with this setup. And here is why I must use a PM42 and not the PM74 is I need there to be 4 inputs for this arrangement. So to answer the question of why would I need 4 separate power sources? Well I have 4 separate lines potentially being powered by 4 separate sources! And the PM42, unlike the PSX or PM74 will provide power management for DC as well as DCC. So my arrangement will be the outputs of each relay board channel will feed into one of the PM42 inputs for a total of 4 inputs feeding the 4 lines for N-Trak. Oh, and I can also run 2 T-Trak layouts with the one command station! Well that’s enough for now.
I haven’t had much progress on this command station setup lately as unemployment doesn’t pay enough to afford all the pieces I need at once. I was able to get a couple more pieces on the way though. I decided that 100% this will have a WiFi server built in as I really like the UWT100 and UWT50 throttles. I found a really good router for $5 plus some shipping, it’s the same one I use for my home network and I know it works great. Then I was finally able to find a Raspberry Pi 5 in stock so I ordered that as well. I still need one more G-scale decoder but they are not in stock where I order from, they say it should be in another week or so. I acquired another relay board which has 16 relays in one unit, and another that has 4 so that will decrease the internal footprint quite a bit, as well as the power demands. I do plenty of other projects so having extra parts laying around is a non issue. I have also decided on a form factor for this contraption. It will be roughly 24 x 24 and the height will be determined by each level’s requirements. Levels did you ask, why yes, there will be levels inside, 3 of them. The bottom will contain the power strip and cord storage, plus any additional power supplies for the various devices above. Middle shelf will be the command station and control relays. There will also be an access door here to select the channel you need for your train. And lastly the top which will house the computer and WiFi router. There will also be a screen for the computer in the lid to this section kinda like my wooden suitcase command station… well in reality I’m going to use the same screen. So that’s that for now, my wood shop will be available here soon to start cutting out and laying out all the bits and put more of this into reality. Stay tuned.
A concerning thought... The DCC decoders use PWM (typically by varying the pulse width within a fixed pulse repetition interval) are probably designed not to generate excessive EMI given typical wire lengths inside the locomotives the decoder is designed for. That may not be the case if you are driving the rails of a large layout, instead of a nearby DC motor, with it. You might think about some low pass filtering (RC or RLC) on the track output, to eliminate excessive noise that could interfere with WiFi or radio throttles, cell phone reception, AM/FM analog radios, etc. The filter will tend to average out the pulses and gaps somewhat, to yield a smooth(er) DC signal for the rails.
I was planning on using some ferrite beads for just that reason, especially after my issues with my passenger station.
So the first of 2 routers showed up today. Like I said before it’s the exact same one I use for my home network. I had to kill the previous owners settings and reconfigure it for my needs. That being done I set up a quick WiThrottle server with the JMRI on my computer and tried to connect with my UWT-100 throttle. It worked like a champ and I’m good to go! The Pi will be here next week so I can get that set up for headless JMRI operation and everything will be right with the world… ok, maybe not the world… yea definitely not the world, but all will be good with this project. Oh, yea, I fixed someone’s boat today and that got me a couple extra $$$ so I ordered my last decoder for the project. I found it on sale from IPH which was a much better price than my usual source. So good to go there as well. I think I need to start getting some wood cut to make this all come together!
My initial thought on this is that Mr. Rueben Goldberg would be proud. Unfortunately, he passed away over fifty years ago. Many Ntrak clubs have a simple set up with a laptop running JMRI. Most venues have WiFi. I use two old smart phones that are dedicated as throttles using Wi Throttle. I can't use them for calling but I have an Android for that. I use two because they are old and the batteries will not last the usual six hours per day needed for the show. We also have an analog connection to any of the three tracks via DPDT center off switch. Any track can be changed from DC to DCC by flipping the DPDT switch. I use the regular Wi Throttle not the Wi Throttle Lite version. Worth it I think, for a one time charge of ten bucks.
