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.