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  1. If you have a bit of space to spare I'd definitely try the solution @UltraViolet proposed, but perhaps then with a step up converter of 3.7->9V? That way it always has full power, not just 5V "backup" power. Only if there's really no space you could possibly try connecting a TCS KA3 keep alive like I did above. I say this because with a battery + 3.5V to 5V/9V step up converter it's much easier to deal with reversing loops and unpowered sections of track. Also, I found the keep alive to be a bit inconsistent when not paired with a buck converter in front of it (I found this out after posting the initial POC, not exactly sure why). Because the battery solution looks to be working so well for me I would recommend that more than the keep alive. If space allows, you could then even hook up a 9V->3.7V step down converter with adjustable current limiter built in, so the battery can charge off track power. You'd probably want a charging rate of 0.5C, so the amps are limited to half of the mAh (e.g. 2600 mAh -> charge at 1.3A). Essentially the same setup I have ebove, but then the battery voltage is different from the PFx Brick, which you solve with 1 extra step up converter.
  2. Well, since I posted I ran into 2 problems with this setup: 1. When put under extra stress (holding back the train simulating pulling lots of cars), sometimes the PFx Brick would simply restart itself, stopping the train. I believe this is caused by slight imperfections in track power pickup, so when a lot of amperage is requested it can't supply it and it restarts. 2. The reverse loop works in the demo, but the dual frog juicer was fried after running my loc full speed over it a dozen times. Basically, from what I understand the dual frog juicer cannot handle any kind of current for a sustained amount of time, which is a problem when used for reversing loops. If only used for turnout frogs, it would have survived a lot longer. The solution: I've taken a similar route of @davidzq and added a battery. This is a 3s1p 2600mAh battery made up of 3x 18650 li-ions. It can output a max of 11A, which is way overkill of course but I thought I'd mention it. It has overcharge protection, so it should not be a problem that it's getting power when it's already "fully charged". The setup looks like this. Track power goes into the bridge rectifier, same as before, that then goes into a step down converter with manual voltage and manual amperage control. Track is ~14V, minus 1.6V for the bridge rectifier, so ~13V going into the step down converter. Then that is set to output 12.0V, with a maximum current output of 1.3A. This output is then connected to both the battery and the PFx Brick. I set it to 1.3A since that is the recommended 0.5C charging rate of the 2600mAh battery. This way both the batteries and the power supply will not overheat. Note how I charge with 12.0V not 12.6V, so that the battery is never full, only at max ~80%. Li ions don't like to be fully charged. I could potentially lower it a bit more, perhaps. But I think 12.0 is OK. About the video below; The straight tracks at the top of the loop are not powered, standard RC tracks. As you can see, when it crosses that part the light switches to green which means the battery is being used for power. When the light is blue, it means it's using power from the track and charging the battery. Essentially this means you can have as many reverse loops as you want, it does not add any complexity. Just make sure there is at least some plastic track to isolate the sections. Also this solves the issue of using 3d printed turnouts and then having to apply copper/aluminum foil tape. Now you can still do that to make it look like it's powered, but it doesn't need to actually supply any power; the battery will take over in those difficult sections! In case you're interested, the locomotive is the SystemTrains big boy model, powered by 4x PF L motors. You can get the instructions on Rebrickable here: . And yes I designed it myself, shameless plug To provide a bit more info (not scientific in the slightest), the 4 L motors pull around 0.4A at half speed and 0.6A at full speed (12V); tested this with the locomotive upside down with no additional load. When holding the wheels down (increasing the load), a very heavy load (many cars) will go to around ~1.2A and almost stopping the wheels at full power showed around ~2A. If we assume 95% of the track provides power, and we use an average of 1.2A, the train will be able to run forever! (theoretically) /cc @Toastie thought you would maybe like to see this In case you want a similar setup, here's the battery and step down converter I bought: Note the battery dimensions (70x37x35mm), it's just under 5 studs wide and with some clever SNOT building techniques could potentially fit in a 6 wide build as well!
  3. Ah, that's also a neat solution! I couldn't figure out how to make it so the battery acts as backup when there is power loss. Does it recharge the battery as well? I can imagine reversing loops are even easier to deal with in your case, just add 1 plastic RC track in the loop (granted you only have 1 pickup point). The only downside that I can think of is that you are limited to the max current of the battery when track power is lost. With my solution, you can keep stacking motors until you hit the 3A limit of the PFx brick. Or is your battery some kind of RC car battery?
  4. NilsvN

    DCC (and other digital tech) for LEGO trains

    This is an older thread but it certainly belongs here, yesterday I finished a 9v track to PFx Brick dcc setup that can handle a 9v reversing loop. No batteries at all and can be controlled by a PF remote or PU remote! Link to my thread: [link] Image of the proof of concept:
  5. Hi all, I've got something cool to share with you. I've been planning how to tackle my next 9v layout where I want to control multiple trains on a interconnected set of loops. On a regular 9v layout, you cannot do that. This is my solution: It's a 9v motor with the motor taken out, feeding into a bridge rectifier (into the A/C connectors) so that the output polarity is always the same. Then from there it goes into a step-up converter set to 10v output (track power is ~12v, but a bit lower on the frog). From the step-up converter it's connected to both a TCS KA3 keep alive and a PFx Brick. The keep alive ensures that the PFx Brick stays powered (and keeps the motors running) if power suddenly cuts out very briefly. Let me explain why that is important: For the reversing loop I'm using a TCS dual frog juicer. Basically, the "loop" part of the reversing loop is an isolated section of track, which we'll call the frog. You connect track power to the dual frog juicer input and connect the output to the frog. When the train drives from normal track onto the frog and the polarity of the frog is "the wrong way round", then it will automatically switch the polarity of the frog. This happens very fast, but it's enough of a delay when going into the bridge rectifier and then into the PFx Brick that the PFx Brick shuts off and turns on again, effectively stopping the train. That's where the keep alive comes in! Demonstration: (watch the indicator LED change between red/green, this means polarity gets switched) 1.mp4 2.mp4 In the demonstration I used a PF remote. For my layout I'm going to be using Vincent Vergonjeanne's fantastic piece of software to control the PFx Brick with a Powered Up remote using bluetooth. That way I can control every train even when they are going through a tunnel for example. Here is the full post about the software: [link] I hope you found this interesting :) Thanks to Lazarus992 for the tutorial on how to open up and remove the 9v motor
  6. NilsvN

    SystemTrains - Union Pacific 4014 Big Boy

    This is actually not that ideas project, my locomotive was built from the ground up :) I could post it on ideas, but am selling the instructions instead because I want anyone to be able to build one for themself. If I were to post it on ideas, I would not be able to share instructions since it is then owned by lego. Would be cool for it to become a set though, but the odds would be slim with the amount of submissions in each review period.
  7. NilsvN

    SystemTrains - Union Pacific 4014 Big Boy

    Thank you so much! That describes it pretty well, no compromises on looks while having all the functionality you could ever want. The Boxpok wheels I'm super excited about, supposedly they are almost ready for production over at HA Bricks. From what they shared on facebook it's going to be awesome once they do!
  8. Hello all, I'm very excited to finally be able to share with you the project I've been working on the past half year. It's a 1:50 scale model of the big boy, with working lights and sound! (yes, another big boy model) Instructions are available, which also includes the PFx Brick configuration file; plug and play! You can build it unmotorized, with 2 or 4 PF L motors, with LEGO PF or PFx Brick, using batteries or 9v. I really tried to include everything and make it as easy and fun as possible You are also able to use a BMR knuckle coupler without needing extra parts, those steps are also included! For more info on the instructions, see here: And if you just want to see (and hear!) it in action, here you go!
  9. NilsvN

    PFX brick Sound with Trains

    @Vilhelm22 Hi Vilhelm, I understand the reasons behind it for sure, I've been following development of the other Fx Bricks products closely :) I'm very stoked for the 9v pickup wheels they announced recently as well. And can't wait to get those P40's in hand!
  10. NilsvN

    PFX brick Sound with Trains

    Looking for this as well. Is there a download of the v.1.50 and v.1.10 files somewhere? It doesn't need to be perfect/finished, just something to tinker with would be nice cc @michaelgale
  11. @Sven J I don't think this was asked yet, or I missed it, how did you get the crank to stay at ~30 degrees? Is the axle glued to the wheel?
  12. Sadly from what I've read on other threads is that the Lego IR probably doesn't work at 12v. It would be nice to have the track continuously powered at 12v to be able to use the Fx motor's full potential. Edit: Just found out the existing PFx brick already supports 12v input. If you input 12v, does that mean the output also gives 12v? Or does it get capped? A 12v to 9v converter cable might still be interesting to people wanting to use a standard Lego IR receiver instead. Especially if you are planning on powering PF motors, with power coming from the upcoming Fx power pickup unit.
  13. The jumper functionality is genius for it being the "dumb" motor. I am wondering though, say you want to connect an IR receiver between the power pickup connection and the motor input connection (common use case). If you want to run the motor with 12v, can the Lego IR handle 12v? Have they tested if it can handle that? Otherwise in that scenario you would be limited to running the motor at 9v. Then the next question would how does the Fx motor (at 9v or 12v) compare to the Lego 9v motor in terms of speed. If they are similar at 9v, then the above might not be much of an issue (but still, would be nice if it worked)
  14. NilsvN

    10497 Galaxy Explorer 90th anniversary set

    Yep, let us buy it already tyvm
  15. NilsvN

    40567 Forest Hideout (GWP)

    Just placed an order!! waiting for confirm