As I’ve mentioned before, electrical things usually come fairly easy to me.  However sometimes those little electrons do their best to stymie me, as I illustrated in another post.  This past week I ran into another of those little gremlins.

We’ve had a lot of rain these past few weeks, so I thought it would be a good opportunity to catch up with the under table electrical work.  I had put in a good bit of trackage over in Monterey, which included the turning wye.  It all had to be connected electrically, so I crawled under the layout and started connecting about a jillion track feeders.

When I initially started my track installation and wiring, I kept a small battery/buzzer device connected to the track which would sound the alarm if I happened to connect something in a way it didn’t like.  However, once I installed my PSX circuit breakers (CB boards), I would get a constant alarm as the device would back-feed through the CB board circuitry.  So, being lazy, I unclipped the device from the track rather than disconnect the main feeds from the circuit breaker.  I was quite careful though, and all my wiring is color coded, so I didn’t anticipate any problems.

Well, I suppose I should have anticipated them because when the wiring was completed and the power was flipped on, the fault light on the CB board lit up with complaint.  Arrghhh!

The last trackage installed had been the wye.  So back under the layout I went, disconnecting track feeders one at a time, starting from the far end.  After all the wye feeders were disconnected, the fault light remained on.  So I started disconnecting the rest of the feeders to the mainline, and yard trackage.  I disconnected every feeder and the light kept glowing.  Now what?  The problem had to be in the track itself.  So I disconnected the CB board and started poking around with my little buzzer device.  I eventually determined that the problem was somewhere in the wye trackage.

One tail track of that wye crosses the mainline utilizing a Walthers/Shinohara 90 degree crossing.  The crossing itself had been a big concern initially because during manufacture it had apparently been removed from the injection mold prematurely and was significantly warped.  I contacted Walthers for a replacement but they had none in stock, and had no ETA for new inventory.  Checking around quite a few mail order shops, I was unable to locate one.  It tested out OK electrically, and I could press it down flat to the table against it’s will, so I decided to go ahead and try using it.  I stuck it down with adhesive caulk and soldered the connecting tracks to it, and this seemed to tame it.

With that background, I strongly suspected that the crossing might be the culprit.  So I held my breath and sliced through one of the rails between the crossing and the wye switch.  I figured that would at least tell me whether the problem was in the wye trackage, or in the crossing.  The buzzer informed me that the problem was in the wye.  Rats!  So I figured I needed to start isolating the switches.  With great difficulty, I managed to slide the rail joiners of the first switch until they contacted a tie.  But they wouldn’t slide quite far enough for me to lift out the switch.  So I carefully cut down through the rail joint and rail joiner on each rail.  Still no joy.  In the meantime Wayne had come over and after looking things over, was just as puzzled as I.

I just stood there leaning on the layout, wondering just what in the world was happening here.  Then I had the epiphany.  One of the three switches and it’s tail track comprise the turning section of the wye, i.e. the reversing section.  It is necessary to gap all four rails of that switch to isolate it from the other wye trackage.  I had dutifully sliced through these rails and filled the gaps with bits of styrene, filed and shaped to the rail contour.  My realization was that I had probably sliced through the rails on the wrong side of the internal jumpers built into the switch.  Again I held my breath and made a single cut through the crosstie that I suspected would surround said jumper, then hooked up the buzzing device.  Nothing…as in success!  Such a rookie mistake.  I had failed to note the internal jumpers (visible from the underside of the switch) before gluing it down.  It also happened to be the last track assembly that I had installed.

I carefully reconnected all the feeders throughout (with the sound maker hooked up), then set about repairing all the damage I’d done to the track during my trouble shooting.  Fortunately I was able to slide those shortened rail joiners back onto the mating rails, then soldered everything to keep it in place.  The initial cut at the crossing was aligned with the aid of a couple tiny brads driven into the roadbed (they’ll have to be painted over or otherwise concealed later), then all soldered.  A piece of styrene was inserted into the severed crosstie to keep the gap from closing.  And finally, I had to run a wire jumper to the short, now isolated rail at the offending switch and connect it to the barrier strip below.  I reconnected the track power, and hit the master switch.  Success!, the fault light was out and the Alco on the siding burbled to life.

I won’t be doing anymore track or electrical work without my buzzer connected.

-Jack

Well, there I go again.  Earlier I posted a column celebrating the completion of all the hardware and wiring for my optical detection system (well, it’s not really complete….I still have to build the panels that will display the occupancy indicator LEDs).

Problem is, I just assumed all readers would know what I was talking about.  Not!  I’ve been informed that I should quit assuming.

So, I’ll try to explain in 3000 words or less, just what an optical detection system is.  Now keep in mind that my explanation here is strictly in the context in which I am employing said detection system.  And I will avoid getting into the directions that the electrons are traveling and the gory details of the circuitry that makes this all happen.

I have six staging tracks, all of which are hidden from normal viewing.  In order to ascertain where a train is while running on this track, I decided to employ a detection system.  There are several ways to detect a train, and I chose to employ optical detection.  The system utilizes photo-transistors (PTs) which can sense whether or not they are seeing light.  When they do, they will turn on, that is, they act as a switch and will close a circuit.  I have installed my PTs centered in the track between a pair of ties, with their tops just above the roadbed.  The PTs are wired to a circuit board located under the layout.

As a light source, I’m using infrared LEDs (IR-LEDs).  To avoid seeing light beneath the layout, and to make the circuit less susceptible to ambient lighting, I chose to use components that are sensitive to light in the infrared range.  This isn’t visible to the naked eye, and in fact, that’s what most TV remote controls use.  The PTs and the IR-LEDs selected are matched to their light spectrum and work in harmony together.  The IR-LEDs are mounted on the “towers” I spoke of in the last post, and are pointed down at the PTs.  They are simply wired to a 12 volt DC bus (a pair of wires).

The circuit board I mentioned above is the “brain” of the system.  The inputs to the board are the PTs.  The outputs are to plain old red LEDs which are used as indicators, installed on a simple panel with a track diagram.  Each indicator LED is placed on the track diagram at the location where a PT sensor is located on the actual track.

With the power on and the IR-LEDs shining brightly, the PTs see the light and the circuit board determines there is nothing out there as no PT is “closed”.  Therefore, no power is supplied to the indicator LEDs on the panel.  But when a train comes along, it blocks the light of an IR-LED shining on a PT below, and that PT turns on, which in turn lets the circuit board know that something is at that location.  It in turn lights up the appropriate panel indicator LED and you now have a visual indication of where the train is.

Simple, huh?

Actually, it really is.  I purchased the circuit boards already built up from a fellow hobbyist up in Canada.  All I had to do was install the PTs and IR-LEDs, and wire them up.

Your test will arrive in the mail later in the week.

-Jack

I can hardly believe it myself.  I’ve completed the installation of all 24 of the photo-transistors (herein known as PTs) and their accompanying infrared LEDs (IR-LEDs) as used in my optical detection system.  Whew, what a job!  Nothing about the project was particularly difficult…at least not on paper.  The premise was simple, the wiring was simple, the hardware was simple.  But the effort to do each task wasn’t trivial, and the collective effort expended was nothing short of colossal.

Installing the PTs was by far the fastest and easiest thing to do.  Simply drill a 3/16″ hole and stick the PT into it.  Didn’t even have to secure them…they are held by friction.  I then ran a 26 pair phone cable around the layout and tapped into it with the PT leads, each PT on it’s own circuit.  The cable ends at a backboard beneath the layout where the circuit cards are located.  I made the tie-ins and the detection circuit was complete.

The IR-LEDs required much more effort.  The IR-LEDs are used as the illumination for the PTs.  I chose to install these up over the track, with the LEDs pointed down over the PTs.  I ended up fabricating a “tower” for each IR-LED.  In fact, I actually fabricated three types of towers as required by different installation requirements.  Using flat metal framing straps procured from Home Depot, the fabrication involved was drilling a couple holes, making some bends in the metal, then installing the towers onto the benchwork.  Later I made up some assemblies, each consisting of an IR-LED, a current limiting resistor, and some wire leads.  I installed these on the towers, ran the leads down below the sub-roadbed, and attached them to the 12 volt DC bus.

Today I applied the power, checked that each IR-LED was in fact illuminated (had to use my digital camera for that since you can’t see light emitted from them with the naked eye), then rolled a boxcar through all the “traps”.  All worked perfectly with no adjustments required!

Here’s a photo of a couple of the towers.  The one in the foreground is a double tower, in that it supports two IR-LEDs (one over each track).  If you go over to the main website, I have photos of all three types.

There is one final task to do before the system is operational, and that is to build three small panels which will contain track diagrams with red LEDs located at appropriate locations.  This will be the visual indication to the engineer as to where his train is on the hidden staging track, and most importantly, when to stop.  I  need to install the fascia before building and installing the panels, so that task will be a ways down the road.

But having the hardware installed over the staging tracks clears the way for me to start the sub-roadbed and trackwork for the upper level above.

Progress is surely sweet!

-Jack

Art Houston sent me an offline comment yesterday in which he mentioned drilling holes through the benchwork joists to act as wire raceways.  I responded to that with the method that I’m using for my wiring.  After thinking about it this morning, I decided I’d share my method with the rest of you.

When I erected my basic L-girder framework for the layout, I used a single “keeper” joist at each leg set location for the purpose of holding the L-girders in position.  As I’ve progressed with the sub-roadbed around the layout, I’ve added joists on approximately 16″ centers to support the risers and sub-roadbed.

Many modelers drill holes through their joists in which they then pull the wires for the various electrical circuits around the layout.  The problem I have with that is twofold: (1) I don’t have all the joists in place so that the wire can be pulled through. (2) Making changes to the wiring becomes more laborious if one has to pull wiring in or out of all those holes.

My solution was to create a series of hangers for the wiring.  For this I use simple EMT conduit clamps attached to the web of the L-girders.

These clamps are available in many sizes; I’m using both 1/2″ and 3/4″.  I buy them in boxes of 100 at Home Depot and they are relatively inexpensive in that quantity.  I use a single 3/4″ hex head sheet metal screw to attach the clamp, oriented in a vertical position, with the screw at the bottom.
I like these screws as I can drive them into the soft pine wood, using a nut driver, without first drilling a pilot hole.

Generally I space the clamps about 12″ apart, with additional clamps located where needed.  I am running my power buses at the back L-girder near the wall, and my control buses at the front L-girder near the aisle.  I also have some special wiring in a couple locations for the optical detectors on the staging tracks.  This is a 25 pair telephone cable that I’m suspending in it’s own set of 1/2″ conduit clamps attached to the bottom of the joists.  I’ve already had to make changes in that wiring and the clamps made it a snap.  Merely loosen the screw at the clamp and slip the wire in or out, then re-tighten.

While not very high tech, this method has served me well on my last couple layouts.

-Jack

Well, benchwork and trackage have taken a back seat for the past 6 weeks or so.  I’ve been dealing with some medical issues and am having difficulty doing many (most) tasks required in the layout’s construction.  But in spite of that, I’m still doing things as I can each weekend.

I managed to get about two-thirds of the optical detectors installed prior to my troubles.  In recent weeks I’ve installed a bit of roadbed at the Willis yard and I’ve made very good progress on my control panel designs.  I plan to have approximately 15 control panels around the layout.  Two of them will be for the yards at Monterey and Willis, and the rest will be “mini-panels”, typically 5″ high x 8″-10″ wide.  These smaller panels will be at the various towns along the line and will contain track plan snippets along with switch position indicators (LEDs) and the toggles used to control the Tortoise switch machines.  A few of them will be used for the hidden staging tracks, with the LED track occupancy indicators giving the engineer visual cues as to where his train is.

I’ll be using the tried and true “sandwich” method of panel construction.  I’ll sandwich a print-out of the appropriate plan between a piece of 1/8″ Masonite and some 0.1″ acrylic plastic.  Next drill the holes for the toggles and LEDs, install and wire same, then mount the panel to a box or directly to the fascia.  I used this method on my last layout and was quite pleased with the result.

Over the past month I ordered all the electrical components I’ll be needing from Jameco Electronics, so I’m now ready to build a mock-up of a panel.

I’ve also been acquiring several other items and materials that I’ll be needing so as soon as my health issues are resolved, I can get back to the heavy-duty construction.

We’re also getting into that time of year where all sorts of railroading events take place.  The calendar is already starting to fill out with planned activities.  I hope to see some of you folks at some of these.  The only event that is still missing is a good train show with vendors.  It’s a shame we aren’t on the regular circuit for one of those.

Any questions or comments?  Please post or drop a line…I like hearing from you.

-Jack

If you are regularly following this blog, you’ll recall the comedy of errors I committed while installing the wiring for the optical detectors a few weeks ago.  I mentioned in that post that I’d decided to rip everything out and start over.

This past weekend I did finish ripping out the old work and I completed the new and improved wiring installation for the phototransistors in the west staging area.  The results were much better than my original efforts.  Armed with the success, I will now repeat the lessons learned over at the east staging area (which is twice the size).

I also have to put in the illumination for all those PT’s.  I’ll be using infrared (IR) LEDs attached to overhead supports, one over each PT.  I have no specs for the IR LEDs that I have, so I’m going to have to assume their characteristics in order to select the current limiting resistors that will be required.  I’ve never worked with IR stuff before, but I’m told that if you look at an IR LED that is turned on through a digital camera, that you can see the light.  I hope that is so, as I think aiming and adjusting will be much more difficult if I can’t even see what I’m trying to do.

Plenty of other things have occurred over the last couple weeks, though mostly things that don’t really show any progress.  I finished installing all the cable hangers for the main cable runs throughout all of the benchwork (a significant task itself).  I finalized what control panels will be required and their locations.  I’ve even started some preliminary drawings for panel layouts.  I’ve coordinated where other things will be on or under the layout’s fascia once it’s installed, particularly the work shelves and throttle plug-ins.  I’ve got the Willis yard ready for track installation now.  I keep a marker board filled with a running list of tasks that need to be done, and I manage to erase a couple each weekend.

I’ll likely be doing wiring for at least several more weeks before moving back to the roadbed and track.  But I figure it’s good to try keeping the electrical and roadbed/track current with each other.

Most of you that are subscribers to this blog are relatively local, so if you’d like to visit to see things for yourself, you’d be more than welcome.  Just drop me a line, and we’ll make it happen.

-Jack