My control panels

My new projects book contains two chapters on building and  installing control panels. Because I decided long ago to use Tortoise switch machines on the new Piedmont Southern one chapter deals with them and DC powered control panels. The second chapter goes into using DCC accessory decoders with Tortoises to create pushbutton control panels. I use Tortoises exclusively on the Piedmont Southern—why, well access can be a problem on a double deck layout. Turnouts easily reachable at 48″ elevation can quickly become out of reach at 60″. And the same is true for areas on the lower level hidden underneath an upper deck. So using Caboose ground throws just didn’t seem reasonable and the alternative was motorizing the turnouts, and to control them you need control panels!

For my control panels I lay out the track schematics on the computer and print them out on glossy photo paper. The first two panels, controlling the Charlottesville industrial district and Charlottesville yard are 5″ x 10″ and 5″ x 14″, respectively. Printing them out wasn’t an issue on my Canon photo printer which can handle paper up to 13″ x 19″. The thing you have to remember is to leave enough room between the switches and LEDs–I didn’t in Charlottesville yard and ended up having to redo that panel.

The big pain is then drilling all the holes in the clear acrylic sheet I used to go over the printed schematic for protection. For this I laid the schematic and acrylic sheet out on the box I had built out of plywood and screwed them down through holes drilled in each of the four corners. I then drilled starter dimples in the acrylic sheet directly over each switch and LED symbol on the schematic. Once all the dimples were started I removed the acrylic sheet and drilled completely through each dimple using a 1/4″ diameter bit. For this you need to work slow on a hard flat surface. One small crack and you have to start over again. I used special bits made for drilling acrylic sheet that I found on eBay and they make all the difference!

With all the holes drilled I thoroughly cleaned all the sawdust and plastic bits and pieces off the acrylic sheet and reassembled the control panel–fortunately the holes lined up almost exactly over the switches and LEDs on the schematic. Next using a new #11 blade in my Xacto knife I carefully cut out each switch and LED symbol from the schematic. I then installed SPDT switches in the switch holes and black plastic mounting clips in the LED holes. Now the fun part, installing the LEDs.

In my schematic I placed a green LED on the leg of the switch that will be the normal position and a red LED for the reversed or thrown position. That will serve as a reminder to the train crews to always leave the switch set with the green LED on. To get the polarity correct requires testing the circuit as you wire them. Basically for each switch there needs to be a green and red LED wired together in opposite polarity. Remember that on LEDs the long leg is positive and the short leg negative. Another indicator is that there is a flat spot on the side of the LED next to the negative leg. I just twisted one short and one long leg together then soldered them. To be consistent I placed the long leg on the green LED and the short leg on the red LED next to the switch and the opposite pair of legs away from the switch. Let’s call these the input and output sides, respectively.

Now let’s digress a minute to talk about powering the Tortoises and LEDs. The Tortoise instruction sheet has very good diagrams showing how to use various DC and AC transformers to power these–I went the AC route. I used a 16VAC 1 amp transformer which can power about 50 Tortoise machines–remember a Tortoise only draws about 20 milliamps when stalled. To get the polarized DC current required for the Tortoise requires a couple 1 amp diodes. By simply soldering the pair of diodes to one of the AC transformer wires you get a positive and negative current. The diodes have to be oriented with the white band in opposite positions to get the positive and negative current–the other wire serves as the return leg of the circuit which I’ll call the common. Again, the Tortoise instruction sheet has a very good diagram illustrating this.

Once the power supply is taken care of, you can start wiring the panel. Well, actually I first attached it to the fascia using hinges so it can be flipped up for wiring and maintenance and down for operation. The first step is to wire up a Tortoise as a test unit to use for wiring the LEDs and switches–never power the LEDs without a Tortoise in the circuit or you’ll blow them. Using a jumper with alligator clips I hooked up the common wire to one pole of the Tortoise motor and ran another jumper from the other pole to the output side of the first LED pair.

Next I set the switch on the control panel to point toward the route with the green LED, and soldered the center pole of the switch to the input legs of the LED pair. Now using the two wires from the diodes I momentarily touched one to each of the outer poles of the switch and noted which LED lit up. I tested until I found the wire and switch pole combination that would light the green LED. Once I found the correct combination I soldered the wires to the switch contacts and moved on to the next switch and LED pair repeating the process.

After the switches and LEDs are wired up you then have to make the correct connections to the Tortoise. This involves connecting the common wire to one motor contact and the output wire to the other motor contact. Using my jumpers and clip leads I tested the wires until I found the polarity that resulted in the turnout lining up correctly with the control panel switch and LEDs and soldered them in place. Again I repeated this process for the rest of the turnouts. One good thing about working on 60″ tall benchwork is you can do it sitting in a roll around office chair. Once everything is soldered in place you just flip the control panel down and enjoy the ease with which you can control turnouts. The Charlottesville yard panel allows the yardmaster to route trains past the yard on the mains or into it from one central position in an area about 25′ long. Well, I now have two done and only about 10 more to go–I think I’ll spread them out over the next year or two.

if you’d like to see how I did the panels using accessory decoders and pushbuttons you’ll have to wait for the new book coming out next summer. I’ll also have even more details on these DC toggle controlled panels. It’s never too early to start priming the pump.


  • Another option we also have now is the Cobalt Digital motors. These are what we are using on our club layout. The decoders are already in the Cobalts thus making total cost of an installation including motor, momentary push-button switch, 3mm bi-color LED (just for panel indication now, track side signals later), and the wiring and a Digitrax DB150 supplying the power for approximately 140 switches at a cost of about $22 per turnout. I love it so far. Have about 20 of them installed so far.

    • I haven’t tried the Cobalts but I do have a couple Circuitron Smails. These are basically a Tortoise with a built in accessory decoder. You can’t beat the track record of Circuitron. They’ve been making the Tortoise since 1985!

  • Looking forward to the book Larry.

  • Larry, that seems like a bit more work than some folks might want to tackle. However, if clear instructions are provided, I see no reason to hold back
    That being said, There may be an easier way to accomplish the set up of switch machines and indicator lighting.
    On my 8’x13′ around the wall layout with apprx. 30 turnouts, I use a double pole double throw toggle switch for each turnout. A 12 volt transformer supplies power for both the Tortoises, and the LED indicator lights. A large enough transformer to handle all the switch machines, and LED’s should be used.
    Here are the main differences between my set up and Larry’s. The wiring for the turnout is fastened to the DPDT switch like we used to wire our old DC layouts, that is, the wires are criss crossed on the switch attachment lugs. When the switch is thrown, the opposite polarity will throw the Tortoise the other way. Only “one” LED is used on the panel at the switch location. it is located right on the intersection of the switch routes. These LED’s are Bi polar, and change from red to green when the switch toggle in flipped. The lead wires for these LED’s are fastened right to the same lug as the switch machine wires. Of course you must use a resistor with the LED’s. I use 1000K.
    This may not be very prototypical, but I use a “second” LED. positioned in a small (1/4″ x 1/4″) tapered block, painted flat black. The end of the LED protrudes out of the top of the little block about a 1/6th, to 3/32′. The wiring is blended into the wiring of the initial LED used for the turnout indicator on the panel. You should use a separate resistor for each LED. The purpose of this second LED at the turnout is so I can see that it is orientated in the correct position, without having to constantly look at the panel. Wouldn’t you rather be watching your train instead of the panel? Of course some modelers may wish to install a second LED, or SMD on the top of a “switch stand”.
    One final note. When using toggle switches on your panel to the throw your turnouts, I use ones that have a “center off” position. That way I am not constantly providing power to the machines. The Tortoise is capable handling this constant power, but I would just rather not use it, if it’s not needed. When the power is turned off on the Tortoise, the wire throw rod will tend to spring back towards a neutral position a small amount, lessoning the force of the point rails against the stock rails, so one should check this to see if the force is still sufficient.
    There are other ways to wire your turnouts. no one way is the “right way”. I would suggest before starting a task such as mentioned in the above comment and post, that you “read” all you can on the subject, and if possible, check with any clubs that may be in your area to see what they have done.

    • Don—I’ve seen panels with bipolar LEDs, all red or green LEDs, and the red-green combination like mine. They all work and are not difficult to install and wire. I chose the red-green pairs for a couple reasons: (1) red-green is sort of a convention among model railroaders with the green showing the normal route and red the reversed or thrown route, and (2) because the illuminated lights clearly show routes through complex trackage, something that the bipolars don’t do. With bipolars you have to know which route is normal and thrown and with only one of them at each turnout they don’t convey directionality. There are several different ways to power all of these and to wire them and once you have done one they become easy to do.

      • Larry, I’d like to comment on your reply. On your second point: When you say the pairs of lights clearly show through the complex trackage, I’m assuming you are referring to the lights on the panel? I mentioned I have a second Bipolar light at the turnout that is either green, or red. I can see these clearly and the red is always the divergence route, the green, strait through.
        I like “night op’s” and these second LED’s make it easy to see which way the turnout is thrown at a glance. As mentioned in my first post, I would rather watch where my train is going, instead of the panel.
        Thanks for the follow up.

  • Two words….touch toggles. Use Touch Toggles by Berretthill makes building a control panel easier than described above. No drilling is necessary.

    • Thomas,
      Your probably right. The first thing I did after reading your reply was to go to their site. However, I’m not getting any sound. tried a a couple of songs, but no sound either, will look into it later.
      I,m kinda operating as a lone soul, no clubs around here, only one other model railroader in this area, and he is even less savvy on electronics than I am. All the info I get is either by reading books (Larry’s of course) or by chance, such as your post.
      I guess the main thing I wanted to relay onto other model railroaders, is that there is such a thing as Bipolar LED’s, in at 3mm size, and maybe larger, and you don’t have to use two separate LED’s, green and red, unless of course you want to.
      I’m anxious to look into the touch switches you mentioned, thanks for the tip.

  • Good point about bits designed for drilling acrylic and other plastics. The difference is that a flat is ground onto the cutting surface so the bit scrapes the plastic rather than digging into it as a wedge. If you are very careful, you can make your own by grinding a flat on the cutting surface that is parallel to the length of the bit, but it has to be even. Much easier to buy them pre-ground.