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Question on using cat 5 cable for LED turnout indicators

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  • Member since
    December 2004
  • From: Bedford, MA, USA
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Posted by MisterBeasley on Friday, October 19, 2012 12:14 PM

That's a reasonable case for designing in something for doing a quick disconnect.  Still, I think I'd use a terminal block instead.  Unless you're already familiar with wiring the plugs and jacks, there's a bit of a learning curve.  A terminal block, on the other hand, is pretty simple and very easy to disconnect and re-assemble, as long as you label the wires.

Oh, thank you for your service, by the way.

It takes an iron man to play with a toy iron horse. 

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Posted by stokesda on Friday, October 19, 2012 8:53 AM

MisterBeasley

How often do you plan to move the panel?  Is this a module moved frequently, or is this something you may do in 5 years if you move?  You may be designing in something you will almost never take advantage of.

Are you planning to run these turnouts with Tortoises?  If so, the Tortoise has 2 of those SPDT toggles.  Since you plan to use a wall-wart for power, you won't be able to piggy-back on the track power, so you can't use the frog-power toggle as shown.  This makes your wiring job much simpler, and you don't need all the extra circuitry to do the job.

I'm in the military, so I'll probably be moving at least twice in the next 10 years. It's been moved twice already. My main concern is not with the plugs, but with the wire itself. I could hard wire the LEDs to the switches, but I figure I might as well install a plug in between while I'm at it. I'm not currently using Tortoises and don't have any plans to anytime soon. I am using a DPDT slide switch from Radio Shack mounted under the layout surface to actuate the turnout. A piece of music wire sticks up through the roadbed to move the switch rod, and a piece of coat hanger wire is used to slide the switch back and forth (or side-to-side, relative to the turnout). The end of the coat hanger wire sticks through the facia and has a wooden drawer knob epoxied on the end. One set of contacts on the DPDT switch is used to power the frog, the other will be used for the LED turnout indicators.

Dan Stokes

My other car is a tunnel motor

  • Member since
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  • From: Bedford, MA, USA
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Posted by MisterBeasley on Thursday, October 18, 2012 8:01 PM

How often do you plan to move the panel?  Is this a module moved frequently, or is this something you may do in 5 years if you move?  You may be designing in something you will almost never take advantage of.

Are you planning to run these turnouts with Tortoises?  If so, the Tortoise has 2 of those SPDT toggles.  Since you plan to use a wall-wart for power, you won't be able to piggy-back on the track power, so you can't use the frog-power toggle as shown.  This makes your wiring job much simpler, and you don't need all the extra circuitry to do the job.

It takes an iron man to play with a toy iron horse. 

  • Member since
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  • From: Eastern Shore Virginia
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Posted by gandydancer19 on Thursday, October 18, 2012 2:09 PM

The CAT 5 wire size will work for LED's with no problems for DC or DCC power.  LED's only draw about 20 milliamps each, so every thing will be fine.

Because the Tortoise switch machine also only draws about 20 ma, you can use the CAT 5 wire to power them as well, if you so desire.  That is what we use on our club layout and have not encountered any problems.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

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Posted by stokesda on Thursday, October 18, 2012 2:08 PM

Brad,

Thanks for the response. After doing a little more homework on my own, I found out that if the CAT 5 cable has 26 AWG wire, it can take up to 361mA (more if it happens to be 24 AWG).  Assuming a standard LED uses ~20mA at 2V (according to wikipedia... yeah, I know Confused), that is a total of 280mA, which is easily within capacity. To be on the safe side, I might end up running 2 separate wires for the "common" with half of the LEDs on one, and half on the other.

Just to clarify what I'm doing - I know my explanation above was confusing and I am probably getting the terminology all wrong. What I'm planning to do is use a half of a DPDT switch to power the frog using rail power and the other half of the switch to power 3-lead common-cathode LEDs. LED power will come from a DC wall wart. The positive wire will be connected to the center position on the DPDT switch, and current would flow to the green or red LED anode depending on switch position. Current would come out the common cathode, through a current limiting resistor, and to the neg wire on the power supply.

Dan Stokes

My other car is a tunnel motor

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Posted by twcenterprises on Wednesday, October 17, 2012 4:15 PM

I see no problem with the voltage, I'm not sure about the current load, though.  Now maybe I'm misunderstanding something, but I don't think a common return will work.  Why?  Because it depends on the polarity of the frog to change the lights red/green.  You'll need at least 7 returns, since you'll have 7 turnouts.  Now you *Can* use common leads, since the stock rails won't (need to) change polarity (assuming you are not using power routing turnouts).  So I calculate you'll need at least 9 wires to your panel.  The leads should be heavy enough to power 7 LED's each, the returns will need to power 2 LED's each.  CAT 5 cable should be enough for the returns (My opinion, haven't double checked, and it depends on the current draw of the LED's)

Brad

EMD - Every Model Different

ALCO - Always Leaking Coolant and Oil

CSX - Coal Spilling eXperts

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  • From: San Diego
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Question on using cat 5 cable for LED turnout indicators
Posted by stokesda on Wednesday, October 17, 2012 12:55 PM

Hi, all,

I'd like to make a control panel with bi-color LEDs to indicate turnout position with 2 LEDs per turnout. Something similar to the circuits shown at the bottom of this page:

http://www.wiringfordcc.com/signaling.htm

Except I'm considering using a low voltage wall wart vice DCC track power. To make the wire connections between the layout and the panel, I'm considering using CAT 5 ethernet cable with standard CAT 5 plugs and sockets so I can unplug the panels and remove them when needed (like when I have to move the layout).

The panel in question would have 7 pairs of bi-color LEDs that would be lit at any given time (i.e. 7 turnouts with 2 LEDs each). I figure I can get the anode leads for 4 LED pairs on one CAT 5 plug/socket, and the leads for the other 3 pairs plus the common on the other plug/socket.

Question is if this is too much current (and/or voltage?) for the individual CAT 5 cable wires? I'm not super concerned about the wire leads for the LED pairs, since they'd only be carrying enough current for 2 LEDs, but the common would be carrying enough current for all 14.

Also, would it make a difference one way or the other if I used track power instead, as shown in the link above? Is one preferable over the other from an electrical/fire safety perspective?

Thanks in advance for any feedback.

Dan Stokes

My other car is a tunnel motor

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