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Help with rotary switch

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  • Member since
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Help with rotary switch
Posted by TJT53 on Monday, February 16, 2009 10:20 PM
I'm building a staging yard (stub end), and need to control power with a Radio Shack 6 position rotary switch (actually 2 of them) How does one wire these? The switch has 12 terminals on the base with two more in the center. Those two are the power leads? Any help will be appreciated. Thanks.
Tags: Wiring
  • Member since
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  • From: Reading, PA
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Posted by rrinker on Tuesday, February 17, 2009 6:42 AM

 The two in the middle would be the input power. At each of the 6 positions, one of the center pins gets connected to one of the 6 on that side, and the other center pin gets connected to one of the 6 on its side. That gives you 6 possible track connections. If you need more, you can connect one output pair as the inputs to the next switch, that will get you 11 total tracks - 5 on the first switch, position 6 on the first will drop over to the second switch, adn you have 6 positions there.

                                              --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by jrbernier on Tuesday, February 17, 2009 7:42 AM

  I would really re-consider using those Radio Shack rotary switches.  The contacts are only rated for .3 amps of current!  Rotating them with power on can burn up the contacts.  They just are not designed to carry heavy current loads.

Jim

Modeling BNSF  and Milwaukee Road in SW Wisconsin

  • Member since
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  • From: Hilliard, Ohio
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Posted by chatanuga on Tuesday, February 17, 2009 9:17 AM

With the rotary switches on my layout, I use the terminals on the outside for power coming in from the six (only four are used) cabs with the two center terminals going out to a DPDT toggle switch to the track.

Kevin

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Posted by tomikawaTT on Tuesday, February 17, 2009 12:50 PM

What you have described is a 2P6T switch - the inner connectors being the poles (power in) and the outer connectors being the output to (up to) six tracks.  The outputs to any single track will be directly across from each other, 180 degrees around the circular contact pattern.

Brother Bernier makes a good point about the meager carrying capacity of the contacts when switching.  If the switch is always thrown when there is no power to the rails, the closed contacts can carry any normal train load - even a seven car lighted (with incandescent bulbs) passenger train powered by a catenary motor with two 1960's era open frame traction motors.  OTOH, if you're using DCC, the rails may be continuously powered and you might overload the contacts if there's a train on the tracks.

These low-capacity rotaries will handle Tortoise loads easily if used as route selectors for powering switch machines.  If you set circuits with the rotary and then fire the switch machines with a pushbutton, they can even handle my huge old KTM rocksmasher twin-coil machines.

Chuck (Modeling Central Japan in September, 1964 - with LOTS of rotary switches)

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Posted by locoworks on Wednesday, February 18, 2009 1:29 AM

tomikawaTT

 

 OTOH, if you're using DCC, the rails may be continuously powered and you might overload the contacts if there's a train on the tracks.

 

Chuck (Modeling Central Japan in September, 1964 - with LOTS of rotary switches)

 

if your using DCC, why would you need sections switched??

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Posted by rrinker on Wednesday, February 18, 2009 6:37 AM

 

locoworks

[if your using DCC, why would you need sections switched??

 Prevent accidents, like running  a train into an already occupied staging track? Or in a roundhouse area, if you have each track loaded up with sound engines, to keep the noise down a bit - or also prevent accidently selecting the wrong loco and driving it into the turntable pit? Lots of reasons to have the capability to turn off certain track sections even when using DCC.

                                   --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
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Posted by tomikawaTT on Wednesday, February 18, 2009 12:49 PM

locoworks

tomikawaTT

 

 OTOH, if you're using DCC, the rails may be continuously powered and you might overload the contacts if there's a train on the tracks.

Chuck (Modeling Central Japan in September, 1964 - with LOTS of rotary switches)

if your using DCC, why would you need sections switched??

Just suppose that you have forty decoder-equipped locomotives on the tracks at one time.  Add in the forty passenger cars, each illuminated with incandescent bulbs, and the thirty-odd brake vans with interior lights and markers.  Even if no trains are moving, that amounts to a significant load on the DCC system.  Now start up a couple of them - a catenary motor with two open frame juice hogs and a steam doubleheader (ditto.)  That bright light you see is the base unit's overload lamp, which came on when the whole system went off-line.

Now, turn off the tracks on which all but a dozen of those passenger cars are standing.  Turn off twelve of the fourteen tracks occupied by staged freights, and the tracks where not-in-use passenger motive power is parked.  Suddenly there's plenty of power for three mainline trains and local switching at Tomikawa.

I rest my case.

Chuck (Modeling Central Japan in September, 1964 - with staging tracks that are dead until selected)

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Posted by locoworks on Wednesday, February 18, 2009 6:03 PM

two good responses to my question, i never really thought about those issues. i did wonder why you would set a point to an already occupied staging line though?? and if you did you would probably power that line too.  the power consumption never occured because my layout is sectioned/blocked  ( i don't have a huge passenger fleet with lights, if i did they be decoder controlled anyway ), and i don't have zillions of loco's or a round house. so for myself the opportunity to over load a section does not exist in practical operating terms. so i've never come accross those issues and it isn good food for thought should my set up ever evolve into a much denser populated layout.

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Posted by rrinker on Wednesday, February 18, 2009 7:44 PM

 Well, if it's hidden staging, unless you have some sort of indicators or a mirror or some way of seeing in there, it's not all that hard to pick the wrong track by mistake. And even WITH help - if you are distracted or something.. some cool things you can do it actually set it up the staging ot automatically line the next available track after you park a train. DC or DCC you can do this.

                                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    February 2009
  • 3 posts
Posted by TJT53 on Thursday, February 19, 2009 12:18 AM
Thanks, guys for so much help. I knew model railroaders were pretty good guys (or gals) but I never got such a great response to a question. (I tried other electronics sites and such) Should have known the best freinds were right in my own backyard. Again, here's to the greatest hobby in the world, and thank you fellow MR's!!!!!! TJT53 P.S. Yes, I did solve the problem, bought 2 rotary switches from Miniatronix which can handle the volt/amp load and include wiring instructions, PLUS thry helped me with LED panel installation too! Great company, just like all of you- thanks again, everybody. Tim Thompson
  • Member since
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  • From: S.E. Adirondacks, NY
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Posted by modelmaker51 on Thursday, February 19, 2009 12:59 AM

Another couple of options for the RS rotaries:

Include a momentary OFF button to turn the power off as you turn the rotary switch. Or use a momentary ON button to turn the power on after the switch has been turned, hold the button in until the loco is on/off the turntable, this is probably the better way as it is a one-handed operation.

Jay 

C-415 Build: https://imageshack.com/a/tShC/1 

Other builds: https://imageshack.com/my/albums 

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