Engineer - Electrical


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"Model Railroad Engineer - Electrical"

I have electricity flowing through my veins - my dad was an electrician, and I took to it at an early age. I really like this much-maligned part of the hobby, and get a special kick out of soldering (go figure).

My layout runs on DCC with two power blocks and two reversing loops, but the regulations when I went through the program required five electrical blocks, plus an ammeter/voltmeter wire-up. To meet the requirements, I divided one of my power blocks into two. I also found an old DC transformer, and wired that up with an old ammeter and voltmeter to a section of track on my workbench.

I earned this certificate on December 12, 2002.

Here's what you have to do to qualify for this certificate (again, it1s been edited; visit www.nmra.org for the full wording):

Construct and demonstrate the satisfactory operation of an electrical control system on a model railroad capable of simultaneous and independent control of two mainline trains in either direction, and containing at least:

1. Five electrical blocks.
2. One mainline passing siding.
3. One reversing loop, wye, turntable, or transfer table.
4. One yard with a minimum of three tracks and a switching lead independent of the main line
5. Facilities for the storing of at least two unused motive power units
6. One power supply with meter(s) and protective devices (short indicator and/or circuit breaker) to ensure safe operation of the supply.

Wire and demonstrate the electrical operation of at least three of the following items (items on my layout are in red):

1. Turnout
2. Crossing
3. Crossover
4. Double Crossover
5. Slip Switch - (single or double)
6. Gauge Separation Turnout
7. Double Junction Turnout
8. Three Way Turnout
9. Gauntlet Turnout
10. Spring Switch
11. Operating Switch in Overhead Wire

Wire and demonstrate the electrical operation of at least three of the following items:

1. Electrical turnout position indication on a control panel or at trackside for a minimum of four turnouts. (All the turnouts on my layout have this separately-wired feature using an LED and separate power source.)
2. Track occupancy indication on a control panel or at trackside for a minimum of five blocks. (I built 8 different detectors for the layout - four from a circuit in an old issue of Model Railroader and which were used on my old layout, and four from a circuit by Rob Paisley which I found on the internet.)
3. Cab control, making provision for connection of at least two power supplies. (I ignored this one because of my DCC)
4. Engine terminal, including an electrically powered turntable. (my layout wasn1t ready for this at the time... and still isn't!)
5. Two turnout junctions with electrical interlocking and protecting trackside signals. (Thanks to the DCC-unfriendly turnouts on my layout, I fulfilled this requirement, but didn1t actually document it in my paperwork)
6. High Frequency Lighting. (ignored)
7. Electronic throttle with inertia and braking provisions. (My DCC system had this built-in, so I didn1t count it.)
8. Grade crossing with electrically actuated warning indication. (I scratchbuilt a detection circuit, again from Rob Paisley1s web page, for this, and figured out a way to have the circuit activate a motor which would move a top-side wig-wag signal; this was a fun project that took me two weeks to perfect!)
9. Two-way block signaling with automatic train detection for at least five blocks. (ignored)
10. Operating overhead wire, using either pantographs, trolley poles, or both for current collection. (ignored)
11. Installation of an advanced electronic and/or computer control for the model railroad. (someday... but for this certificate I wasn1t ready with this)
12. Design, installation, and operation of animated mechanical and/or electrical displays. (ignored)
13. Design, installation, and operation of mechanical and/or electrical layout lighting displays. (ignored)
14. Installation of a command control receiver. (I had done this in my IHC Mogul)
15. Installation of a command control throttle buss line around a layout capable of handling at least two throttles at three or more separate locations. (I certainly had this)
16. Construction and installation of a sound system. (ignored)
17. Construction and installation of a signaling system. (ignored)
18. Development and installation of a CTC system. (ignored)
19. Installation and operation of an on-board video system. (ignored)
20. Computer generated block detection information. (ignored)
21. Hardwired or stored control program (i.e. computer) for operation of the railroad. (someday.. ignored for now)
22. Development and demonstration of a computer-to-railroad interface. (ignored)

Prepare a schematic drawing of the propulsion circuitry of the model railroad in (A) showing the gaps, blocks, feeders, speed and direction control, electrical switches, and power supplies. Prepare schematic drawings identifying the wiring and components of the six items above.

I really went to town on the documentation for this certificate, producing a 20-page full color booklet, which, even at the highest compression rating, comes out to a 7meg PDF file. So I'm reproducing parts of it here.

Description of items in “B” and “C” on Qualification Form

TURNOUT

The Bona Vista railroad uses Walthers/Shinohara Code 83 turnouts exclusively. These turnouts feature an all-metal frog, and are pre-wired with both points electrically connected, and the frog electrically connected to the points. Consequently both frog rails beyond the turnout need to be gapped.

Electrical contact of the points and frog is accomplished with a slide switch, mounted on the fascia, which is manually thrown by the operator. The slide switch changes the position of the points and changes the electrical current in the points and frog. See the enclosed diagram.

Components used in the slide switch arrangement include a Radio Shack Heavy Duty DPDT slide switch, a length of heavy metal rod (I’ve used wire from a suspended ceiling), and a cabinet knob from Home Depot.

CROSSING

At present there are only two crossings on the Bona Vista trackage -- both are Atlas 20-degree crossings. These crossings feature plastic (insulated) frogs, so electrical continuity is relatively simplistic.

Instead of diagramming the wiring of those, I’ve chosen to diagram the wiring of a metal frog crossing, such as I scratchbuilt for my Civil Engineer Certificate. That wiring is far more complex and a lot more interesting; the diagram is enclosed.

CROSSOVER

All crossovers on the Bona Vista railroad are built from facing Walthers/Shinohara Code 83 turnouts. Therefore the description here is the same as that of the Turnouts, above. However, a separate wiring diagram for the Crossover is enclosed.

TURNOUT POSITION INDICATORS

Turnout position indicators, wired to all Bona Vista turnouts, utilize red LEDs and a 1K ohm resistor. The turnout position indicators run off of a separate 12vdc transformer whose bus wire encircles the layout on the benchwork below. The LED is then mounted to the fascia board opposite the turnout. A wiring diagram for these is enclosed.

TRACK OCCUPANCY INDICATION

There is a good deal of hidden trackage on the Bona Vista, both mainline and staging. In all cases I’ve used one of two different electronic track occupancy indicators. In some cases I’ve utilized a circuit, designed by model railroader Rob Paisley, featuring an IC chip and infrared LEDs and detectors. In other cases I’ve used a circuit designed by Eric Bracher which uses transistors and visible light.

The Paisley circuit was found on his internet page; the Bracher circuit was published in a 1973 issue of Model Railroader. In both cases, however, I built the circuit myself from Radio Shack components, using only the circuit printout as a guide.

The Paisley circuit uses a single comparitor chip that allows for four individual occupancy circuits. Thus, this circuit is used in two different areas of the Bona Vista railroad on hidden mainline trackage. The four indicators show a train’s progress through the trackage. A third Paisley circuit is used in Smithtown, a two-track hidden staging area, to show both occupancy and when a train has reached the end of the staging tracks.

The enclosed diagrams show both the circuit itself and how it’s implemented on the BVrr.

The Bracher circuit uses visible light as a source, and will light either a lightbulb or LED. I’ve used 5 of these circuits on the BVrr to light a small panel located at Froton. Because Froton is a visually isolated portion of the layout, the Bracher circuits show operators switching Froton the general whereabouts of through freights, so the mainline can be cleared in time to allow passage.

The enclosed diagrams show both the circuit itself and how it’s implemented on the BVrr.

GRADE CROSSING WITH ELECTRICALLY ACTUATED WARNING INDICATION

ANIMATED AND/OR ELECTRICAL DISPLAY

Because track occupancy isn’t that far removed from grade crossing protection I emailed circuit designer Rob Paisley about adapting his track occupancy circuit (above) for use with a wigwag signal at a grade crossing. Rob made several modifications to the circuit design to adapt it for use here, including a 5-second shut-off delay and use with a relay. Again, while he designed it, I scratchbuilt it with Radio Shack parts.

The grade crossing at LaPointe has a swinging wigwag signal and an audible crossing bell. The signal itself was kitbashed from a non-animated model by American Limited. Several modifications to this model yielded a good looking wigwag which could be made to move. I adapted the mechanical portion of the signal from a 1992 Model Railroader article by Woody Langley. A diagram showing the mechanics of the signal is enclosed.

The electronics of the grade crossing feature the modified Paisley occupancy circuit. In this case a pair of infrared LEDs/infrared detectors is positioned 12- to 18-inches from each side of the grade crossing. When a train breaks the IR beam, the circuit electrically closes a mechanical relay. The relay starts both the crossing bell (an electronic circuit manufactured by RAmodels, Inc.*) and the electric motor that powers the wigwag’s target.

Schematic and implementation diagrams are enclosed.

(* Note: While the RAmodels crossing bell is the circuit currently installed on the layout for judging, I have experimented successfully with a Radio Shack digital recording chip, which will eventually replace the RAmodels bell.)

INSTALLATION OF A COMMAND CONTROL RECEIVER

I have successfully installed a Digitrax DH 142 receiver in a non-DCC-ready IHC 2-6-0 Mogul. Because the requirements for the EE certificate requested schematics or diagrams for three items, I have not included them for this item.

INSTALLATION OF A COMMAND CONTROL THROTTLE BUSS LINE

A Command Control Throttle Buss Line has been installed around the entire perimeter of the layout. Because the Bona Vista uses Digitrax DCC products, I’ve run Digitrax Loconet cabling (6-wire cable) behind the fascia boards of the layout, and am currently using 3 UR-90 Infrared Receivers and 3 UP-3 Universal Panels within the Loconet. These 6 panels are strategically positioned around the fascia board.

Again, because the requirements requested schematics or diagrams for three items, I have not included them for this item.

Turnouts on the Bona Vista railroad are Walthers/Shinohara Code 83, in which the frog is electrically connected to the joined points. Turnouts are manually controlled using a rod connected to a DPDT slide switch. Besides imparting physical movement to the points, one pole of the switch lights a divergent route indicator LED, and the other pole, shown here, sends electrical power to the frog/points. Only the frog rails need to be gapped.

Although I've used Atlas crossings on the Bona Vista railroad (which are prewired and have insulated frogs) I'm showing the wiring used for the crossing I scratchbuilt as part of my MMR/Civil Engineer certificate. This crossing had soldered frogs and uses a DPDT slide switch to power the rails.

Electrical Turnout Position Indicator

Turnouts on the Bona Vista railroad are manually controlled using a rod connected to a DPDT slide switch. The slide switch provides physical movement to the points. In addition, one pole of the switch provides electrical power to the frog/points. The other pole, shown here, lights an LED when the turnout is set to the divergent route. The power for the LED is a separate 12vdc circuit, not track power.

Track Occupancy

Track Occupancy on the Bona Vista railroad comes in two “flavors”: the first is modern circuitry using an integrated circuit chip and infrared LEDs, the second is 30-year-old technology using transistors and lightbulbs. While I didn’t design either circuit, both were hand-built by me using the circuit diagrams included here.

The Paisley Occupancy Detector

The following circuit was designed by Rob Paisley and posted on his website at http://home.cogeco.ca/~rpaisley4/CircuitIndex.html. The circuit is based on an LM339 Comparitor chip, which actually contains 4 identical circuits -- meaning, this single circuit can be used to detect trains at four different points on the layout.

I’ve built three of these circuits (total of 12 detectors) for the Bona Vista railroad. Each of them is used to detect the presence of trains in hidden trackage (either staging or below scenery).

The circuit works as follows: an infrared (invisible light) LED is placed above the track and shines on an infrared detector (transistor) mounted between the ties below the track. When a train breaks the beam, a visible light LED lights on a control panel. In the case of the Bona Vista, the LED is mounted on the fascia board near where the detector is located, thus indicating the passage or storage of a train in the hidden trackage. Each of the four detectors of this circuit are placed at equal intervals along the track, so it’s easy to watch the progress of the train through the hidden trackage.

Overview of the Paisley occupancy detector on the hidden mainline beneath Colfax Yard. The circuit is at the top, while connections to the IR LEDs, detectors, and fascia lights are on the bus strip at bottom.

Closeup of the circuit itself.

How the Paisley occupancy detector is implemented on the BVrr

The Bracher Occupancy Detector

The second occupancy detector used on the Bona Vista was designed by Eric Bracher and published in the December 1973 issue of Model Railroader magazine. It was also featured in an article I wrote entitled “Situation Indicator Uses” which was published in Model Railroader’s first “Electronics Symposium” column in November 1980.

This circuit uses a 12v light bulb (or ambient room light) and CdS Photocell to detect track occupancy. Five of these circuits are in use on the Bona Vista to both detect the presence of trains in hidden staging, and to detect the passage of trains past specific points on the layout.

As with the Paisley circuit, the detector (CdS cell) is mounted beneath the track.

The Bracher circuit in use on the Smithtown staging track

The Bracher circuit as published in the November 1980 “Electronics Symposium” column

How the Bracher circuit is implemented on the BVrr

Grade Crossing / Animated Mechanical & Electrical Display

The town of LaPointe on the Bona Vista railroad features an animated wigwag signal, built from three different sources. The wigwag itself is a modified American Limited model. The actuating circuit is a circuit custom-designed for this application by Rob Paisley (and now found on his website at http://home.cogeco.ca/~rpaisley4/CircuitIndex.html) and hand-built by myself. The animation mechanism was adapted from an article in the April 1992 issue of Model Railroader authored by Woody Langley, and entitled “Amaze your friends with a working wigwag.”

The Electronics

The electronics for the wigwag are similar to those for the Occupancy Detector in that an infrared LED and infrared detector are used to sense the presence of a train. However, at my request circuit designer Rob Paisley made some modifications to the circuit, most notably adding a 5-second delay to the shut-off time. I found that while switching the town the wigwag would stop when the engine and single car was between the detectors... and right in the middle of the grade crossing. Instead of the single IR LED/detector pair, there are two pairs, located approximately 18” from each side of the grade crossing. The detectors are wired in series, so the circuit is activated if either one of them receives no light. Also, these are “across the track” rather than “above the track” (as with the occupancy detectors) and mounted at an angle so that spaces between cars don’t affect its operation. Both the IR LED and detector are hidden in scenery.

Unlike the occupancy detectors which turn on a panel LED when a train breaks the light beam, this circuit trips a mechanical relay. Attached to the relay are contacts for both a motor to drive the animation, and a commercially built bell sound module.

It ain’t pretty, but it works. This shot shows the activation circuit, the sound module, and the animation motor.

A closeup of the activation circuit, with the mechanical relay at the top.

How the circuit is implemented on the BVrr. Note that the occupancy detector activates a relay, which turns on both the wigwag motor and the bell sound.

The animated wigwag as it appears on the grade crossing just outside of LaPointe on the BVrr layout. The piano wire that moves the target has been painted flat black, and is barely visible at the top of the mast.

The Mechanics

Rather than scratchbuilding the wigwag signal, I found a static model by American Limited and modified it for animation by cutting a slot in the top of the mast, and enlarging the hole that the target swings from.

A small brass rod with an inverted “U” at its end was added to the target, and an inverted “L” shaped piano wire was run up the mast of the wigwag. The opposite end of the piano wire was attached to a cam which was, in turn, attached to the shaft of a motor which turns at a prototypical 42rpm.

When the activation circuit is tripped, the relay starts the motor. The “L” shaped rod rises and falls within the wigwag mast and catches the “U” shaped target rod, which slides along the short leg of the “L” as the target goes back and forth.

The mechanics of the animated wigwag. Note that this is not to scale.

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