Saturday, October 31, 2015

Helix progress

Work has been progressing on the helix.  This photo shows the helix as it currently is.  Both yards are tied in now with the outer loop from the upper yard climbing a little more than one turn and the inner loop from the lower yard climbing two full turns.

The inner loop from the lower yard and the outer loop from the upper yard each have there own power district.  Each turn of each loop will have a feeder.

I picked up a roll of 16 gauge paired wire from to use as the main bus that will connect the inputs of all the PSX modules in the layout to the DCC system.  That is the black and red wire shown in this photo.  The outputs from the PSX power district modules are 18 gauge.

One of the reasons I am using the threaded rod design is to have the ability to experiment with the performance of equipment in pulling a given train up the grades and make adjustments if needed.  The last layout had 4 % grades which worked fine but those were short and the trains I ran on that layout were normally only 8 or 9 cars long.  I knew the grade would have to be less than that on the helix.

I started out with a rise between turns on the helix of 3 inches.  This calculated out to being 2.5 % on the outer loop and 2.8 % on the inner loop.  Then I began to run trains up the helix with various types of cars and locomotive.  I plan to run locomotives in pairs on most trains and most of the sidings will hold about 20 or so fifty foot cars.  With the 3 inch rise the 6 axle units did fine but the 4 axle units would start to loose traction about the time the full train was on the grade.  So I began to adjust the levels of the helix downward.

What I settled on was 2 - 3/4 inches between the levels.  That 1/4 inch seem to make a big difference.  Both 4 and 6 axle pairs of  locomotives can now pull trains longer than the staging sidings up the helix.  With 1/2 inch thickness of the decks, there is 2 - 1/4 inch of clearance which is plenty for the highest cars and my small hands still easily reach between for cleaning track for re-railing a car.  So far, with all my testing not a single car or loco has derailed within the helix.  So the final grade on the helix is going to be 2.3 % on the outer loop and 2.5 % on the inner loop.

Once I decided on the space between levels, I cut a piece of scrap material to use as a height gauge.  Adding the 1/2 inch thickness of the plywood structure to the 2-1/4 inch space make each turn lift 2 - 3/4 inches.

Another tool I made was a double ended guide with a stop that rest at the inner edge of the deck and lengths for the inner and outer loops.  Once the lines are drawn, the installation of the cork road bed and track goes easily, two sections for half a loop at a time.

I have noticed that the helix sections seem to have a little twist in them after being installed which makes the spacing vary a bit between some levels.  While this does not seem to affect the operation in any way I would still like to keep the spacing consistent so I may add some thin spacers between the threaded rods.

Sunday, October 25, 2015

A simple voltage regulator

In my recent post Powering panel LED's from DCC signal I showed how I used the fact that DCC power was being switched on and off on the staging tracks to activate the track selected LED's on the control panel.  I also have LED's on the control panel to show the position of the turnout that creates the reverse loop.  I did try out connecting to the DCC signal and switching one side through the contacts on the Tortoise switch motor but the LED's did not turn on and off reliably for some reason.  So a DC power source was going to be needed for these and other LED indicators around the layout.  I already had an unregulated 12 volt DC power bus set up to operate some of the electronics around the layout but for LED indicators so I made up a small regulator board for this purpose.

This photo shows the 5 volt DC voltage regulator mounted inside the control center.   This small PC board measures 1.875 x 2.875 inches.  The heat sink may not be needed for light duty applications but I had it in my stash of parts so included it.

Here is the schematic for the circuit.  The .1 uf capacitor may not be necessary if the circuit is just powering LED's.  I have found in the past these regulators can have some noise on the output that can create problems for logic circuits and by habit always include it in my regulator circuits.

Parts List

  • 7805 voltage regulator (Radio Shack 2761170)
  • (2) T3 LED's
  • 1.8 K ohm, 1/4 watt resistor
  • 470 ohm, 1/4 watt resistor
  • PC board (Radio Shack 2760150)
  • (2) 2 position terminal blocks (Mouser 158-P02ELK508V2-E)
  • .1uf, 15 volt tantalum capacitor (Jameco 33486)

The parts I used were all items from my parts stash.  The vendors and part numbers are shown as an example, these are common parts available from many sources.

Here is a close up of the control panel for the upper section of the west staging yard showing the LED's for the return loop turnout being activated.

On my panel pushing any track selection switch to the right sets the turnout to the aligned route shown here.  Pushing them to the left sets the turnout to the diverging route.

Monday, October 12, 2015

1 year since construction started

It's been just about one year since construction started on the layout.  Here's what got done on the layout in that one year.

  • Staging yard bench work built, track laid, wiring done, and yard installed.
  • 15 feet of LED layout lighting installed.
  • Yard control panels started and one completed.
  • Started the helix.

Today I built the little bridge section seen in this photo that connects the upper level staging yard to the outer loop of the helix.  This section will support the turnout that creates the reverse loop for the upper yard.  Helix progress has been stalled until this is done.  It will be the last of 16 code 80 turnouts associated with the staging yards.

The helix design has been working out really well so far.  The lower level yard is fully installed and various types of trains that been run up and down the helix to iron things out.  Turnouts on the lower yard have to be moved by hand as the control system for that part is not done yet.

So what will I accomplish during the second year ?  Well, I'm looking forward to finishing the helix and building the bench work Wesso Junction and Carlin sections.  I'm also looking forward to working with the code 55 track that will be used after the helix is done and of course starting some scenery.

Tuesday, October 6, 2015

Powering panel LED's from DCC signal

When I was checking the yard ladders for power I was using an LED wired in series with a resistor.  It occurred to me that were a track circuit was being switched on or off the indicator light could also be powered from the track.

This is the control panel for the upper or WP yard.  The LED for track 3 is lighted indicating that is the track that is energized and the turnouts aligned for.  The indicators for the turnout on the lower left are not yet connected.

The occupied LED's were put on the panel with the plan to do something with occupancy detection later.   Those will most likely not be powered by the DCC signal.

Here is the back side of the control panel showing the connection.  The track selected LED signals are the wires connected to the green terminal strip.  The current limiting resistors on the PC board are 330 ohms.

The other end of those wires are simply connected to the terminals for track power.  To keep things straight I color coded the wiring for the tracks on this yard as follows 1 = Red, 2 = Yellow, 3 = Green, and 4 = Blue.   This photo shows the connections for tracks 3 and 4.