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posted: 20 Nov 2019 20:28 from: Andy Reichert click the date to link to this post click member name to view archived images |
I've just been through the hassle of figuring out the 2 rail wiring underneath the quad 90 degree rail crossing portion of my new Grand Union. 726_201428_570000000.jpg As you can see above, just for the central crossings alone, there are 16 separate switchable corners on each of four 90 degree crossings. 726_201440_400000000.jpg My wiring diagram above was simplified as I'm using DCC with the same power block for the whole crossing And assuming either all N-S travel or all E-W and switching the whole section accordingly. Nevertheless, trying use bare wire due the shallow depth of the street sections, still caused construction problems where two (or more) wires needed to cross over. In the end I realized that a simple 2-layer PCB, using heavy current tracks, was a much easier and simpler solution. 726_201406_300000000.jpg Here is the the test PCB that arrived earlier this week. The PCB track spacing is 2" for 00/HO. The PCB is the same exact size of the crossings section and will be just screwed in underneath. The droppers from each of the crossing corners will pass down through the large plated thru co-located holes to be soldered. The 4 smaller holes on the LHS allow my bare wire connections to be made, without any crossing over wires to worry about. The layout of the PCB is such that it can be cut up and used to more easily wire any normal railway single or double crossing or linear set of linked crossings as well as quad one used for the Union. Hopefully, I'll be able to show a running video in a few weeks time. There still needs to be a lot of work with relays as many of the other possible Grand Union routes will require DCC polarity reversals. Andy |
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posted: 20 Nov 2019 21:21 from: Martin Wynne
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Andy Reichert wrote: Hi Andy, That's very clever! It does look a bit expensive though? But your statement: just for the central crossings alone, there are 16 separate switchable cornershas me pondering. On a conventional diamond-crossing, only the two V-crossings need to be switchable. The two K-crossings can be permanently on the feed or return side respectively. Especially if the supply is DCC and doesn't need to be split into track sections. I don't see why increasing the angle to 90 degrees should change that? In which case you have only 8 switchable corners. In that area at least -- one or two more leading into it. cheers, Martin. |
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posted: 20 Nov 2019 21:58 from: Paul Boyd
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Martin Wynne wrote: Andy Reichert wrote:Hi Martin I don’t know who Andy used, but I’ve recently discovered AllPCB in China. Just ordered ten boards, 1.25” x 2.5” for just over £18 total including postage. They arrived the other day and are fine. That’s going to transform some of my thinking! Andy - that’s some seriously impressive trackwork!! Cheers, Paul |
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Last edited on 20 Nov 2019 22:00 by Paul Boyd |
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posted: 20 Nov 2019 22:43 from: Andy Reichert click the date to link to this post click member name to view archived images |
The PCB came from PCBway in China. 10 boards up to 10cm by 10 cm Double side boards for US$5, but US $23 Shipping. So it pays to design several different trial boards per order for much the same shared shipping cost. Larger quantities of a single design are of course charged at normal (but reasonable) rates. I'm open to being mistaken on the number of connections. My reasoning to date is that these crossings are chained in pairs in both N-S and E-W directions, so the pairs of what would be common frogs are separated by other gapped differently switched frogs. So they each need separately wiring to, even tho' the same corners on each individual crossing are all commoned. Hence only four wires going into the board. But also note I do need to be reverse the input polarities of all 16 together when I change from N-S to E-W if the different leaves of the Grand Union are temporarily connected to reversed "wye" DCC sections, due to using the curved routes. I think there are some routings I cannot use simultanously, due to commoning both sides of the double tracks. But that's angst for a later time ;) Andy |
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