Sunday, June 12, 2011

Starting to build the X&O RR

The parts needed to lay down the track for the X&O RR had spent long enough sitting under my bed.  Today was the day they came out.  Back in March, I printed out the layout 1:1 on a sheet of blueprint paper.  I've been putting off assembly because I wasn't quite sure how I was going to put everything together.  The goal is to end up with track on roadbed on plywood.  With the layout in 1:1, we obviously want to put the paper on the plywood to assist with placement, but what then?  Obviously not an unsolvable problem -- I just needed to figure out how I wanted to do it.

Today, I decided how, and did it.  I used thumbtacks to attach the 1:1 sheet to the plywood.  I then placed every turnout on the layout, and partially nailed them down.  I also built the connecting pieces for the switches which are really close together, and placed (and lightly nailed) every other piece of non-curve track.  The curves will be flex track, and will involve some nudging, so I didn't bother trying to fix their positions just yet.  Here's everything lightly-nailed:

Then I removed everything, annotated the holes so I know where to pick up next time, and labeled all the pieces.

One little snag I hit.  My shiny new Xcelite 170M shear cutters ... well ... sheared:

I tried to soldier on with the cutting of custom-sized connecting pieces from Flex Track without the shear cutters, but the quality of the cuts suffered pretty dramatically as a result.  Right tool for the job and all that -- this is pretty clearly a necessary tool.

Before laying the track, I tested each turnout.  I first tried hooking the turnouts up to the rail outputs of my DCS50 DCC controller.  I figured that DCC looks an awful lot like AC, so maybe it'd work.  It made the turnout solenoid vibrate, but not much else.  A Google search revealed a number of turnout guides which mention using the AC Accessory outputs on the controller to power the turnouts.  Alas, I have no such output.  It looks like I need a separate power supply for the turnouts.  Whether that's a straight DC power supply with individual switches or something fancy like a Digitrax DCS64 (to allow DCC switch control), I have yet to decide.

Back to turnout testing.  When I realized that I couldn't use the DCS50, I hooked the turnouts up to my bench DC power supply.  At 15V (and a power-supply-imposed max of 1A), most turnouts switched properly, if a bit hesitantly.  A couple of them got stuck.  Turning it up to 20V fixed that problems.  I don't know if this is an artifact of my use of the bench power supply or something more.  Will I need something like this capacitive discharge controller?

I had intended to move straight from this initial placement step to the laying of roadbed and track, but now I realize that I need to think more about how the wiring will work.  If this layout were on a table, that'd be easy -- I could drill holes, and route the wires under the table.  As my wires will share the same side of the plywood with the track, I need to figure it out now.  So much to do.

Monday, June 6, 2011

Transistor basics with DC

Hack a Day pointed me to this blog entry for a basic description of transistor operation with DC. For whatever reason, I had the hardest time getting transistor operation right in my head at first(*). Anyway, the video in that entry is exactly what I wish I had back then.

(*) It could've been because I started with The Art of Electronics, which is a bit like drinking from a fire hose.