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Concentric rotaries

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I found this concentric rotary switches ELMA C07 Concentric www.elma.com/us/products/rotary_components/Coded%20Switches/32Since my electronic knowledge is a little less than my Nuclear physics knowledge I wanted to ask if anyone knows if we can use these switches without too much trouble for NAV/COM radios (if a simple implementation like Knitter or Kdarling method is possible).Thanks in advanceTassos

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Guest kdarling

Interesting find. Concentrics are rarer than they should be.However, this switch is not made of concentric rotaries. Instead, it has an inner rotary with an outer 3-position single-pole double throw (SPDT) (on-off-on) switch.The inner rotary is apparently available either with Hex or Gray code output, which means there would be four output wires to send somewhere. That's a lot of I/O lines to take up, and you'd need special soft/hardware to decode.Ooops, baby in my lap, gotta run.Kev

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It's also possible to do concentric ones yourself with a bit of hackery on the hardware..http://www.flightsimnetwork.com/dcforum/DCForumID12/246.htmlhttp://www.fsnordic.net/discussion/index.p...y&threadid=7949See these threads for pics.The first one shows a nice way of making a concentric hack with two gears.The second one is in finnish but the pics speak more than the obscure language ;-)Basically, I had two cheap rotary switches (that fsbus can uses as "encoders") - and I took the "outer" one, disassembled it (watch out for the two metal bearing balls and the spring want to escape from you :)) Then I cut the 6mm shaft of the rotating bit and drilled a 6mm hole through it, and replaced the shaft with a piece of 6mm aluminium pipe. Thus it now had a metal shaft, but it worked exactly like before. Some superglue made it stick very well. Assembled the switch back. I had to cut the spring into two very short bits now (about 4 rounds each) since there is no longer a hole through the shaft for the spring, so it needs to be just two short springs on both sides of the aluminium tube shaft. Then put the springs and the metal bearings there and assembled the switch back. This needs some practice and finger acrobatics.. http://tigert.gimp.org/vatsim/cockpit-stuff/knobs7.jpg The metal tube shaft glued in..The inner hole in the pipe is 4mm, so I then took a 4mm drill bit and drilled through the end, making a hole in the back of the assembled switch. It doesnt hurt for the contacts anyway, so it could be conveniently done.Then on the inner switch (the one that sits on the back) I just drilled a 4mm hole on the shaft itself (one needs a drill press for these things to make it straight really) - and glued in a 4mm metal shaft to extend the 6mm one. This goes through the outer switch.Then you need to make that angled metal "holder" for the switches so that they dont rotate against each other.It works very well. It's a bit of work, though if you make several at once it is not that hard once you get the idea. Also $50 for a cole-switch concentric rotary makes this well worth the effort IMHO.Tuomas

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