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Addendum to “Electrify your train switches” Dear all, much has been said and shown about ways to electrify LEGO 9V/PF train switches. Along with the EB electrify your train switches thread and some other posts on EB and elsewhere there hardly is anything interesting to add. But then … as said before, I am just wrapping up more than a decade of years of fun with my train layout. My switch electrification approach is far less driven by achieving “to scale modeling” or “most elegant solutions”, it is governed by “using as many diverse LEGO motors as possible” on a more or less standardized and simple drive base design “using as little parts as possible”. I simply like to make efficient use of the stuff in my LEGO boxes – since there are about 30 switch points on my layout. There are a couple of my personal design lines: Since some areas of the layout are rather “dense”, the footprint of the drive mechanism should be as small as possible A clearance that is a little greater as compared to the original configuration with the manual switch stand installed. The reason is that some of my rolling stock MODs/MOCs have a fairly large “overhang” in curves and thus need some additional clearance when passing switch points The switch drive should not fall apart even after prolonged operation as almost half of my tracks are hidden behind bookshelves and other furniture. No modification of the switch – this means that the force required to throw the switch is often considerable. The rendering below shows one very simple base design for my switch drives. It consists of a couple of Technic as well as plain bricks and plates. The rendering is already 5 years old – time is flying. This particular drive mechanism has one serious disadvantage: Operated with the full torque of the PF motors (e.g. with the PF bang-bang remote #8885) it falls apart after five or so cycles. This issue is rather easily overcome, when the torque of the driving motor is adjusted via power control and pulse timing using a programmable brick as for example an RCX or Scout. It took me ages to figure out how to accomplish that: Adjust the length (e.g. 0.3 s) and the power (on LEGO’s 0 – 7 range) for the motor “on” state. This LDraw file contains all the above varieties; the individual sub models combine to any of the drives shown. (Note that you may need to install the unofficial LDraw library as of 2016 to correctly load the files). Alternatively, paying more careful attention to the original EB switch point electrification thread entry (https://www.eurobricks.com/forum/index.php?/forums/topic/44821-electify-your-train-switches/&page=3) would have told me that Jonathan uses his NXT to do exactly that – and for long! The switch is thrown by a lever, which fits into the space between the two mounts for the manual switch stand. By small variations of the actual gear configuration, almost all typical LEGO motors can be attached. The geared varieties [e.g., PF M motor (#8883), Technic mini motor (#71427, #43362), Technic motor geared (#47154), or even the Mindstorms MicroScout PBrick (#32344] are driving the lever with none or low additional gearing ratios; the ungeared Technic motor (#2838) requires higher gear ratios to work properly. The advantage of this drive design is the footprint (as measured on the floor, not height!), which is 3(x6) studs for clearance and 5(x6) studs for the base = 8(x6) studs. The picture below shows two MicroScouts on the bridge operating the two switch points on the right. There are light fibers plugged into the MicroScout’s light sensors; these do transmit the VLL code generated by a Scout PBrick (not visible) to control them. MicroScouts operating as “intelligent motors” for switch drives are fun. The “forward/reverse” “switch” is somewhat unique: When the MicroScout is put into “P” mode it pays careful attention to its built-in light sensor. In this mode, the MicroScout understands some VLL (LEGO’s Visible Light Link protocol) commands such as “motor on forward” etc. In other words you can operate the switch using optical signals from a VLL source. The rendering below shows a Scout controller operating 4 MicroScout switch drives. This version of a switch drive has the smallest depth I could come up with to securely operate unmodified switch points: I used that one on my layout here: Here is the link to the LDraw file. In the mean time I have slightly modified the “RailBricks #9 challenge” drive (a number of ingenious train experts have contributed to this one – see the "Challenge reveal" article by Benn Coifman in RailBricks #12, page 37) and reduced the size to 5-wide at the base. This drive never falls apart, regardless how much torque is exerted on the driving axle. The design is simply amazing! I have retrofitted almost all of my switch points with this version. When a MicroScout is operating the drive, it should be oriented such that you can easily get access to the buttons (on/off, select, run). There are several drive versions to attach the MicroScout in such way that is does not interfere with the required clearance on the point and good access to the buttons. Here are some real world examples: This folder contains all LDraw files Best regards, Thorsten