Model Railroad simple Electronic Additions

Railmodel Electronics A collection of Simple electronic Projects for the Railroad Modeler

Š 2020

This book presents a number of electronic projects for the railroad modeler who wants to enhance the layout and add more realism without a lot of expense.

Projects in this book will use readily available components and simple circuits that can be assembled without needing to understanding a circuit schematic diagram or to find special printed circuit boards.

Project Index on next page

Some of the projects were originally presented in the NMRA ‘Scale Rails magazine’ Train Position Detectors

Using a CdS cell with LED output A Short Track Break - with Opto output

Page 6 Page 7

--------------------------------------------------Utility Power Supply

A Resistor selectable voltage - from the DCC supply

Page 9

Using a computer Hi current, multiple voltage power supply

Page 11

--------------------------------------------------Timing Circuits

Basic timer IC

- 555 description of operation

Page 12

Basic flasher - Utility circuit, DCC powered

Page 13

FRED rear end LED - with optional power sources

Page 15

--------------------------------------------------Automatic Operations

Automatic Turnout and Reverse Loop controller

Page 17

A Train Shuttle controller for DC power

Page 21

--------------------------------------------------Signals

An Intermediate signal - DC track signal with power control

Page 24

Single Line control/acquisition signaling

Page 27

- Linked Departure signals Flashing yellow signal aspect

Page 31

Grade Crossing Signals

Page 33

--------------------------------------------------Other circuits

Simple CAB for Yard or other motors

Page 36

Servo motor controller for points or semaphore signals

Page 38

Carriage Lighting for all scales

Page 41

---------------------------------------------------

Troubleshooting

So it doesn’t work and you have checked everything.

Go here and follow the help steps - see pages 4 & 5

To “http://railmodel.design” my web site for discussion on how to build a layout.

The index shows the page numbers of the chapters.

To get to a page use the page selection slider at the bottom of the Issuu page.

Got a question, email to “railmodel@gmail.com” Page 2

To Construct these Circuits.

You will need some soldering skill which is easy to pick up with a little practice. A number of internet web sites can be found with instructions and advise on the equipment needed.

A cheap volt/ohm meter would be a help if things don't work as they should.

Each project will show a picture of the finished item, a graphical representation of the components in place on the circuit board, a diagram of where the copper strips on the underside of the board are to be cut and for those who can read them, the schematic diagram.

You will find assembly instructions with each project as well as optional changes to modify the performance.

If the instructions and diagrams are followed carefully then a going project should result. If not turn back to the index page and follow the trouble shooting procedure link.

Component links go to suppliers, links and part numbers to order from them.

Soldering is no big deal but many people are put off by it.

There are only three things to remember: • Clean metal surfaces • A flux to make the solder flow • Solder to cover the copper and wick up the component lead.

Clean the copper before you do anything to it. If it has been around for a while it will have a tarnish on it so use steel wool to brighten it up. Similarly the component leads, if they are not new may need to be burnished or scraped with a blade before soldering.

The Solder Wire used for electronic work has a flux in the center of the solder and this is usually sufficient to cover the immediate area of soldering. Some will be left and spill over to the between tracks area but can be washed off with solvent when finishing the job.

Put the 25 watt or similar iron with a pencil bit to the component lead and the copper strip together, count two and push the solder wire into the heated area and iron tip. It should melt immediately and flow out over the copper and the lead. Pull the iron up the component lead so extra solder does not spill over to other copper tracks.

If the iron is not hot enough or too small a wattage it will lose heat to the copper and the solder will take a second or two longer to flow. The iron tip should have a covering of clean solder but not an excess which will spill onto the copper. If the work is not clean the solder will not flow and will form a blob on the component lead.

Page 3

Some considerations and basic procedures 1.

Get out the magnifying glass and carefully check each copper strip for solder spill overs to adjacent strips or across copper breaks.

2.

Running a craft knife blade along the gap between the strips also helps to locate spillover solder.

3.

If you have a multimeter check the +12 input to Ground The resistance should be high, you could also meter between the copper strips for unseen shorts.

There will be shorts if link wires connect the strips, so check for them.

4.

Do a visual check of the components and link wires for position, polarities and the values.

5.

Diodes transistors and capacitors are polarity sensitive so check that they are the right way round. A reverse connected capacitor or diode will draw a lot more power and overheat, even explode after a few minutes.

If you are certain that there are no faults then it is time to apply the Power .

Again a multimeter is good value.

1.

Connect the meter to plus and minus points in the circuit and apply power if the voltage is not what it should be then there is a Problem.

2.

If no meter then the only sign of a fault might be a component getting hot and smelling, or even worse smoking.

3.

If you have no meter then put a 21 watt car bulb in series with the power lead. If it comes on then investigate and find what is drawing so much power.

With no wires, components or soldering out of place then the circuit should be working.

Time to connect it into the layout or a test setup.

If not working then it is time to understand the schematic and with a meter check for realistic voltages across the various components.

If you get half the voltage you expect and it is a timer output then the output may be oscillating rapidly between on and off.

Page 4

TROUBLE SHOOTING A.. Use a magnifying glass to check for potential short circuits - Look along the gaps between the copper - is there any solder bridging the gap.

B.. Trim component leads and link wire ends - Are any of the component or link wires bent across the gaps C.. Finally check with a knife - run a knife blade along the gaps to find whisker of solders D.. The cuts in the copper strips.

- check that they are all cut right through.

- A meter is a help here.

E.. Are components etc in the right place - double check the component positions - is the component polarity correct - are the copper cuts in the right place F.. Meter for these power problems - check plus and minus power input for shorts - check all ground connections are made - check all plus power connections are made - check that IC pins go to the correct component Finally..

- it should be safe to apply power for a few seconds - do LEDs power on?

- no smell of something heating up Now..

Power on again and measure with a meter the voltages on some of the obvious components, IC pins etc. If all look more or less correct you probably have a going circuit Page 5

Chapter 1A Page 6

DC DCC

The Photo resistor, sometimes called a Light Dependent Resistor (LDR or CdS cell), should have a light on resistance of about 1,000 to 5,000 ohms. They are sensitive to visible light and can be packaged in metal cans or encased in moisture resistant epoxy.

Adjustment:Set the 20K potentiometer at about half way and with the photo resistor covered (Dark) by whatever you are sensing, adjust the potentiometer so the LED is on at the brightness you want. Uncover the photo resistor and the LED should go off. If not readjust so the LED is less bright.

Installation:The photo resistor needs a moderately strong ambient light to reduce its resistance to a low enough value. If there is not enough light where you want to Operation:place the detector then a small The light shining on the photo bulb will need to be installed to resistor makes its resistance low shine on the cell. You could mount which makes a low voltage on the this low down to the side of the transistor base (b). This is passed to rails and shine it up across the the emitter (e) but will not be space that the train will pass sufficient to light the LED. When the through and on to the photo photo resistor is covered its resistor mounted above and on the resistance increases to a high value, other side of the rails. A shield or gives a higher voltage on the emitter tube could be put over the light to and current stop it being visible from the side. flows from the collector  to the LED. Many other means of getting light To operate reliably a 3 volt battery is to the detector could be devised. needed. A multi-output Plug pack, 3 to 12 volts unregulated DC could be used in place of the battery. The circuit will work up to 12 volts from a DC power supply but care is needed in the adjustment as the LED could be burnt out at the higher voltage.

Current

drain:-

If you are using a battery, the current drain of this circuit will be about 0.25 milliamps per detector, which should give it several months operation on 'D' cells.

However you will probably have several detectors running through a tunnel or along a hidden yard and supplied by the one battery so a power on/off switch would be advisable.

Construction:The components can be mounted on a piece of strip board (vero board) and can be fitted into a 4 hole by 10 hole area - see diagram.

The picture shows the CdS cell mounted on the vero/strip board but it can be on flying leads somewhere on the layout and the LED and PCB mounted on a convenient track side panel.

Multiple PCB's and LED's could be mounted side by side as they are very small.

Chapter-1c Page 7

This Spot Detector for a DC powered track will be activated when a locomotive wheel set is bridging between the isolated track and the powered rail.

The DC Track voltage will be between 2.8 volts and 12 volts, plus or minus, depending on the motor speed and direction. It may be a constant voltage or pulsing from 0 volts to 12 or higher (some pulsed or PWM throttles can go higher than the 12 volts that the Construction motors are specified for). A small square of strip board or components and connecting wires The circuit is quite simple. As the train wheels make contact between the isolated track and the main track a circuit is completed and the track voltage is supplied to the rectifier. The voltage, rectified by the bridge, produces a DC voltage.

The Optical Coupler contains both an infrared LED and a photo detector such as a silicon diode, transistor or Darlington pair. With current flow in LED it shines on the Transistor which conducts and connects the two output pins.

4N25 Optical Coupler

This activates the optical coupler and the 'output' is connected to the 'Gnd' (ground) internally. This grounded connection can then be used by following low power circuits.

0 ma is the maximum current output If more current is needed then a transistor or a relay should be added. But the output is a pulse or series of pulses as the train passes the spot.

vero board, 14 holes by 5 can be used to hold the components. The bridge Rectifier type W04 (round) is mounted in 4 holes and will need the holes enlarging to 1.2 mm (#56).

On the diagram the light holes and bars are the copper clad tracks which run horizontally on the underside. The dark holes are where the

are soldered and the 'X' marks where the copper is cut from around the hole to break the track circuit. The components sit on the topside.

The cuts on the copper side are in column 10 and at rows 1, 2, 3 and 5. Twist a 1/8" (#31) drill bit in the hole to shave off the copper and leave a break in the strip.



Chapter-1c-2 Page 8

DCC This Spot Detector for a DCC powered track will get a constantly alternating voltage when a locomotive wheel set is bridging between the isolated track and the powered rail. This voltage will be between 12 and 16 volts. It is rectified by the bridge rectifier to produce a nearly constant DC voltage which through the 1000 Ohm resistor activates the LED in the Optical Coupler and connects the ‘out’ line to the 0 volt or Ground potential.

Installation Make a small isolated track section. It need be no more than two sleepers long - see appendix also.

First solder a dropper wire to the outside of the rail flange of the rails on both sides. Spread some epoxy over the rail flange and around the sleepers where you will cut, to stabilize them. Cut through the track on one rail in two places down to the plastic base. A Dremel cut off wheel is the best, but if you use a small saw then protect the opposite rail with a piece of metal sheet over it. Try and keep the plastic intact and the track section height in line with the powered track. Which track is isolated does not matter. Run wires from the droppers

Components Resistor items: 330 ohm or 1,000 Ohms. Which Other A Bridge Rectifier type W04 one depends on the power source (round) An Optical Coupler, type 4N25, 4N35 or similar.

Capacitor 100 ufd at 6.3 volts for the DC Strip Board 14 by 5 rows. circuit Note: for a DC detector the low speed voltage may not be enough Take the 'Out' and 'Gnd' from the to power a 4N25 Optical coupler PCB to the next circuit. so a 4N35 type should be Remember it will only be a short substituted. trigger pulse present while the wheels are on the track section.

to the input on the PCB.

Solder on the droppers and fill around the sleepers with epoxy to stabilize them..

2 cuts are then made with a Dremel cut off wheel.

The gap is filled with styrene to prevent shorts. The rails should remain at the same height.

On new track cuts can be made from the bottom up to the rail head, but not through it. Gaps are filled with styrene. When the track is laid then epoxy around the sleepers and use a razor saw to cut through the rail head.

Page 1

Chapter 2a Page 9

Utility Power Supply

This power supply can provide a localized DC voltage source from the DCC track supply. Designed to be used for low current accessories such as crossing lights that do not need a lot of current and where running a special cable from a remote DC supply may be too complicated.

copper strip and 1 is now the bottom left corner.

Double check the position and twist a #31 (1/8 inch) drill in the marked holes to remove the copper. Clean up the wisps with a knife and check with a meter that there is no electrical circuit across the hole.

Some of the component leads are larger than the PCB holes and a #56 (1.12mm) drill will be needed to enlarge the hole.

Solder in the wire cross links. Use solid single strand insulated wire. "Cat 5" communications cable can be used for these link wires. Solder them in and cut off excess.

Insert the resistors and diodes. Double check the positions and polarity before soldering them in. Follow them by the larger components, again checking the polarity of the capacitors. The legs of the bridge rectifier can be bent to fit it close to the board or just push it down as far as it will go and solder.

Check the copper side that no solder is bridging between the copper strips.

Running a craft knife blade down the insulation between copper strips will usually find solder bridges.

Construction: Cut the strip board 18 holes wide by 6 rows deep.

If you want to allow mounting holes or input/output terminals expand the size to suit. It helps to put masking tape over the extra unused holes.

Mark the position of hole number 1 on each side to help alignment then mark the position of the copper cuts (X on diagram) note the board has been flipped vertically to show the

Select the correct resistors (R1 & R2) from the chart to give the voltage that you need it can be 3, 5, 6, 9 or 12 volts. To get the best voltage range the resistors must be 1% tolerance or selected with an Ohm Meter.

With these the voltage variation will be less than 2% on most voltages. Install terminals or wires as required and test.

Chapter 2a-2 Page 10

Soldering notes :When you solder, touch the hot iron to the lead and the copper strip, push the resin cored solder onto the joint and when the solder runs along the copper and round the lead, slide the iron up the lead to leave a clean wick of solder running a little way along the copper and up the lead. Do not make solder blobs, they usually mean the solder has not attached to the metal. i.e. something was dirty.

How it works

The LM317 Integrated Circuit

The LM317 series regulator I.C. is used as it can be Voltage Regulator easily setup to a specific voltage. The 1N4004 diodes will damp any high voltage spikes from an inductive load that could damage the regulator. This multi voltage regulator is used in many Most DCC boosters run a track voltage in the 15 to 18 volt range with current capacity of at least 4 amps so the supply of a low current accessory circuit will not impose any great load on it. The regulator does need at least 3 volts more than its output, so a 15 volts DCC input is the minimum for a 12 volt output.

The DC generated is pure DC without as much voltage ripple of the sort you would get from a mains transformer driven supply. The D C output is not isolated from the track power, so this is best used for stand alone accessory circuits.

The voltage output depends on the ratio of the selected resistor and the 240/270 ohm one (R2). The more accurate this is the closer to the voltage you will get.

Resistors of 1% tolerance are recommended and these will give a 0.6 volt spread at 12 volts. These are more expensive but becoming more readily available. Most resistors now are sold in at least packs of 5 so a selection can be made. The reference resistor change allows a more accurate voltage to be obtained.

applications. It has a regulation range of 1.2 volts to 37 volts from a 40 volt max.

DC input. The regulator has a basic 1.2 volt regulation between the output and the adjust pin. The output is then raised above the 0 volt supply line by the resistor connected between the adjust pin and the 0 volt line. The IC is protected internally from thermal overload and short circuits.

The output current can go to 1.5 amps. If over half an amp fit a heat sink to it.

There is no protection from voltage spikes on the output line so to protect against these damaging the IC from inductive or capacitive loads, two diodes must be included in the circuit.

Table of 1% resistor values Voltage = 12v, 9v, 6v, 5v, 3v R1(Sel) = 2,200 1,500 1,000 750 360 R2 (Ref) = 240R 240R 270R 240R 270R LM317 Integrated Circuit Regulator W04 Bridge Rectifier 1.5 amp Capacitor round 0.1ufd disk capacitor [0.1u] Diodes Resistor 1% at R2 shown as Electrolytic capacitors 10ufd at 16 volt working [10u] 1 of 1N4004, 1 of 1N4148 240 ohm resistor [240R] Perforated Strip board Or 270 Ohm as per table [270R] 100ufd at 25 volt working 18 holes wide by 6 rows R1 is a 1% Resistor, as required [100u]

Components

Chapter 2d Page 11

Multi Voltage Power Supply

Most layouts will need an extra power supply to run utility circuits. Signals, lighting, signs etc are all going to need some power source. Here is one way to obtain a multi voltage, high current and readily available supply There is available a ready built utility supply in the Personal Computer that most people now have. Most computers die or are replaced every 5 or so years so why not recycle a bit of it for the layout.

You might get one for the asking at the local computer shop if they throw them away or there might be a collection point for old computer gear at the local refuse collection center. Or they can be bought new for under $100 at a computer hardware supplier.

The part we want is that box that the power cord plugs into. It may have an on/off switch on it or the switch might be on the front of the PC case. There will be a lot of red/orange/yellow/black wires coming out of it and going to parts of the PC. Unplug them, then remove the 4 screws holding the power supply box to the rear of the PC case and wriggle it out.

Once out you will see a lot of dust, a fan also covered in dust and lots of wires with plugs on.

Take the top off and get to work on the dust. Turn the box upside down and brush as much as you can off of it and into the bin.

Remove the 4 special screws from the fan mount, note which way it goes, slip it out and give it a good brush down, including the air slots it sits against.

Remove the wires from the exit holes. Separate them and their plugs and note the ones that went to the socket on the main board. Cut all the wires to the other plugs close to the circuit board in the box and discard them.

If the power switch has been mounted on the front panel of the PC you must decide what to do with it.

I use it as is, mounted somewhere on the layout. Or wire across the leads and eliminate the switch, which would mean you need to switch off at the wall when leaving.

Any PC less than 10 years old will have a switch on the back of the power supply. It will use a control wire that is grounded by the front panel switch to start the computer. The power switch on the box only puts the supply into standby mode.

There should be a label in the top cover that gives you the specifications and with luck the color codes of the various wires.

Construction Mount a terminal strip on the top of the box and route the wires to it. The black wires are all common and are the ground [0volt] return wires.

Color codes in general are:For older supplies with mains power switches, red for 5 volt, orange for +12volts and blue for -12 volts.

WARNING: Fuse each voltage line

Newer supplies [less then 10 years old] also have a 3.3 volt wire and this is orange. Then the +12volt wire will be yellow.

There will also be a green or gray wire going to the 4th pin in the plug. This is the power on control [p-on] you must connect this to the black wire beside it [pin 5] for the supply to come out of standby mode when the power switch is put on. Join the 2 wires and insulate them off.

Snip off any other unused wires.

Having connected every thing up, replace the top cover and the supply is ready.

Chapter-3a Page 12

This simplest of timers will flash the LED at a constant rate. It could be used anywhere if powered by a DCC derived Utility Power Construction:

The Basic Timer The Schematic: When first powered on the capacitor is at 0 volts and this enables the trigger, pin 2. The output at pin 3 will go positive but is not used. The capacitor then charges through the 1 meg Ohm resistor and LED. When pin 6 is at 2/3V voltage point, the output and pin 7 will go to 0 volts (ground). This turns the LED on. The capacitor is now discharged to the 0 volts at pin 7 until the 1/3V point is reached and it retriggers.

The components are mounted on a 9 by 5 row piece of strip board. On the copper side mark the holes to be cut and after double checking them use a #31 drill twisted in the hole to remove the copper so the strip continuity is The 555 Timer broken.

On the top side install the two jumpers. This timer was first made in 1971 and has been produced in billions since. It is a very cheap, popular and useful precision Note one is under the IC, use an uninsulated wire here to reduce height. timing device that can be used either as a single pulse generator, long time delay or an oscillator.

Insert the resistors and capacitor. Turn The 555 timer chip is an extremely robust and stable 8-pin device the board over and solder the leads to that can operate in many different ways. For timing, driving or as a bi-stable memory. It is available in standard, low power or dual the copper strip. Check the relationship to the cut holes before you forms. Perhaps the most used Integrated Circuit of all times by the general experimenter, it forms the basis of many of these solder. It is easy to make a mistake. projects.

Solder everything, install the power wires and wires to the LED. That is about it. Check carefully that there are no solder bridges between strips, use a magnifier or meter.

Apply power, 9 to 12 volts, and the LED should start flashing. For two LEDs alternating, install an LED and 680 Ohm resistor between pin 3 and ground.(0 v)

The heart of the device is the three resistors that form a voltage divider chain. The 1/3 V comparator will produce a low output when the Trigger is below the 1/3 V level to set the flip flop. This makes the output positive at close to the +ve voltage potential.

The 2/3 V comparator will produce a low output when the threshold pin is above the 2/3 V level. This will reset the flip flop.

The discharge pin is a grounded level when the flip flop is not set and a floating condition while the flip flop is set. It can also be used to drive external components. When reset pin 4 is at ground it holds the flip flop in a reset condition which over rides the set input.

Chapter-3b Page 13

An LED Flasher

Many things flash around our roads and railroads. Turn indicators, warnings on utility vehicles, road works, ambulances, grade crossing advanced warning signs, airport beacons, tower warning lights and flashing signal speed indicators.

This simple circuit, runs on 9 to 15 volts which is derived from the DCC track voltage. It can be put right where the light is needed. There is no control on the circuit, it will flash whenever the DCC voltage is present. The circuit is built around a type 555 timer [LM555, NE555 or similar] which is used in astable operation, ie. continuous. The capacitor and resistor, R3, determine the flash rate which can be varied by changing the component values.

With the components shown it will flash at about a 2 second rate. A range of 1/4 second to 2 seconds is possible by changing the resistor to values as shown in the table.

There can be one LED flashing on and off [with R1, L1] or with R2 and L2 added, the two LED's will flash alternately. The resistors R1 and R2 can be changed to alter the brilliance of the LED if needed.

This circuit works with colored or white LEDs. Amother option is to drive a string of LEDs in series using a lower resistance. For example 4 LEDs would need a 220R resistor at R1 and/or R2.



Chapter-3b-2 Page 14

Another view of the components layout

Components: LM555 timer I.C. (MC4555 and many other variations - but don’t use ICM555’s) W04, 1.5amp bridge rectifier - Round form Capacitor 1.0 ufd tantalum capacitor - timing capacitor 10 ufd 25volt axial electrolytic capacitor Resistors 2,200 Ohms - [2k2] 1 meg Ohms - [1M0] or as required - see table 1k0 to 1k8 dropper resistor (R1 and R2) P C Strip Board (Vero board type) 15 x 7 rows.

390R 1K2 33K 47K 1M0

390 Ohms 1,200 Ohms 33,000 Ohms 47,000 Ohms 1,000,000 Ohms

2 1 1 3 2

orange-white-brown brown-red-red three orange bands yellow-violet-orange brown-black-green

Optional timing resistors for R3 ON/OFF Time 1m0 - 2 seconds 560K - 1.5 seconds 220K - 0.6 seconds 100K - 0.25 seconds

| orange-white-black-black | brown-red-black-brown | orange-orange-black-red | yellow-violet-black-red | brown-black-black-yellow

Chapter-3e Page 15

A Flashing Tailend Light The flashing rear-end device, part of the "FRED" box, is mounted on the end of North American freight trains that run without a caboose.

One can be constructed from a small LED, mounted in a model TIBs box on the last wagon. It could then be wired back to the electronics and battery etc. hidden out of sight in a box car for example.

The new metal hydride type batteries now becoming available do have a higher capacity and will need a higher charging current which can be got by changing the 1K resistor to 560 ohms. A 5 volt 1 Farad capacitor with a 3.4volt zener diode across it will act like a short term battery and charge up in minutes when set on the track and last for an hour or two when taken off the track.

The timer I.C. used is a TLC555 CMOS low power type that will run on 3 volts and it directly drives the LED. A switch is included in the circuit as the power drain is It can be used for a hazard light on the cab roof of a diesel loco, a road about 5 to 8ma. hazard light or wherever you need a The flash rate can be varied by changing the 20K ohm resistor. warning light on. If you run on DC As shown it will flash about 3 the 1K charging resistor should be times per second. With a 27K changed to 680 ohms but the loco will need to be run at more than half resistor the rate would be 3 flashes in 2 seconds. speed to get full charge current.

Construction is on a small strip There are several ways to provide the battery power. Two standard AA or AAA cells could be used without the recharging part. On test one has been running for seven days on two recharged alkaline cells. A good source of small 3 cell batteries giving 3.6 volts is an old cell phone, provided it wasn't thrown out due to weak batteries. Or you could buy a cell phone or computer mother board rechargable Li-ion cell, they tend to be a little expensive but should last for many months if switched off when not in use.

There was an Integrated circuit available a few years ago that flashed an LED from a 1.5 volt battery and needed only a capacitor to control the flash rate. The battery had a life of several weeks so it could be left running all the time.

However it is not available now and a 1.5 volt battery will not work an LED on its own with sufficient brilliance.

This flasher will do the same job with two more components and can be run from a variety of sources and recharged from the track power.

board and the 3 pairs of wires coming from it are for the battery, switch and DCC connection. If you are using it as a tail-end flasher then the power will have to be picked up from the bogie wheelsets with small wire wipers contacting the metal wheel rims or the axles.

The strip board diagram shows the I.C. TLC555 shaded so the link wires underneath can be seen. The pin 1 position is shown . The I.C. will have a small dot or depression beside this pin The capacitor can be bent over to lie on top of the 20K ohm resistor and link wires so the overall height is kept as small as possible.

Observe the + lead position, the longer lead wire is usually an indication of the + (positive) lead on the capacitor case. Do solder the link wires in first, but if you don't they can always be soldered underneath later.

Chapter 3e-2 Page 16

Components Resistors 1 of 1000 ohms, [1K0] 1 of 20,000 ohms, [20K] 1 of 100 ohms [100R] Capacitors one of 0.1 ufd one 10ufd 16 volt tantalum or 10ufd electrolytic capacitor a TLC555 integrated circuit timer one diode 1N4004 a small on/off switch 10 by 10 hole strip board.

If you are not charging a battery The component layout for the full circuit.

The 10ufd electrolytic capacitor has been Laid into the space above the 555 IC

or running on a DC track then the circuit board can be modified by not installing the diode and 1000 ohm resistor and the board size reduced. A smaller cut down PCB can then be made by removing the last 3 rows.

The battery connects to row 3 hole 1 positive and the negative to row 4 hole 1 without changing any other components.

The LED shown is a 2 mm base with a 1.2 mm stud. Which when scaled is a 18 centimeters square and 10 centimeters stud. Close to what is needed for a Fred Box.

If only a battery will be used then the size of the board can be smaller. The battery leads are on the left (Red and Black) and those to the switch are on the right.

Note the capacitor is a tantalum type which is a lot smaller.

With smaller components and some redesign the board could be made even smaller

Chapter-4a Page 17

Automatic Turnout Operation

Sometimes it happens !

A sudden stop and perhaps an alarm sounds and you've done it again! forgotten to set the turnout.

Maybe it is out of sight or poorly situated and not obviously set the way it should be. Of course a 2 aspect ground signal would be an advantage, but better still would be automatic operation of the turnout.

This circuit will show how to overcome the problem if you use Circuitron Tortoise motors. Originally designed for DC but it can be modified for DCC On timeout the power is operation as well. restored and the train proceeds.

The time is long enough for the Tortoise motor to transfer the On the red colored track there are two turnout. If the turnout is set correctly then the train does not spots where the train will be sensed as it stop. Also shown is the frog moves toward the turnout. When a train enters at (A) it will be detected passing the power connection which is 'spot loop'. If the turnout is set for the Main supplied by the other changethen it will be transferred to the Loop side. over contacts in the Tortoise.

Optional manual control is by a A timer is started and the track power momentary contact toggle removed. switch (ON-OFF-ON type).

The block diagram:

Installation: There is an edge connector plug available for the Circuitron Tortoise motor. This may be more convenient than soldering on wires under the layout. The numbers in the schematic refer to those on the motor.

The plug is double sided and if the motor is not working in the correct sense i.e. select main and you get the loop, then the plug only needs to be turned round and reinserted to get correct operation. The switch connections will still be correct as the reversing of the motor will change them over. If the turnout changes in the wrong direction but is correct when using the manual switch then the connections to the tortoise switch need to be swapped over.

The position of the spot rails will need to be determined on the layout. They must to be far enough from the turnout so that the train has room to slow down plus a bit more. The controlled track section (from 'A' to the spot) must be long enough to hold all MU'd locos. For detail on making the spot rails see the appendix.

The 100 ohm resistors are installed as shown in the track connection diagram.

Chapter-4a-2 Page 18



Construction: Cut the vero board to size. Thirtythree holes along the copper buss and 20 holes high. Clean the copper and mark on the copper side the positions of the cuts - 'X' on the diagram. Double check each one before you make the cut. Twist a 1/8 inch (#31) drill in the hole to remove the copper from around it. Remove any small copper daggs that still remain and burnish the copper to flatten it again. Check with a magnifier or meter that the copper is gone and no circuit exists across the holes.

Install the 20 link wires. Use a small diameter single strand, insulated copper wire, such as Kynar 'Wire Wrap' wire. Note that there are some links to install under other components (shown in red), these can be bared wire to reduce the height. Next install the 7 resistors and 4 diodes, observe that the banded ends are correctly placed.

The rest of the components can now be installed. Some holes have to be drilled out to 1.2mm (#56) for the larger leads. The PCB connections can be -

soldered direct or solder lugs can be used. If you use plug connections run jumper wires to the original positions.

When finished check all solder joints with a magnifier.

Run a craft knife blade along the insulation strip between the copper strips

If it snags there may be a solder short between the two strips.

Meter again across the cut copper holes for any solder bridging them and also meter between the +12 and 0 volt pins for possible short circuits.

Chapter-4a-3 Page 19

Schematic: The circuit is in three parts. The two spot detectors that sense the train passing are optically coupled to the LM556 which is the Tortoise driver and to a relay to remove track power while the turnout motor is changing.

The LM556 is a dual timer that houses two LM555 chips. These are not used as timers but are set to either on or off to supply the power to the tortoise motor. The sense circuit is connected to the opposite points position switch in the Tortoise. This means that the train can come in through the main or straight through point and not change the turnout when it crosses the spot detector on that track.

The spot's 'opto 4N35' output to the LM556 is a 'low' level and this is presented to the reset input of one of the timers and the trigger input of the other to generate the correct voltages for the Tortoise motor.

NOTE: for DCC operation the 390 ohm resistors (390R) at the bridge rectifiers should be 1,200 ohm (1k2) and the OPTO's changed to type 4N25, the 100ufds caps changed to 10ufd electrolytics.

The output from the spot detector also activates the relay driver, a 2N4403 or 2N2907 transistor, to pick the relay. This will remove the track power feed. A capacitor discharge time delay holds the relay on until the turnout has changed. There is an un-committed 'low' going output from the tortoise driver (pin 1) that could be used for signaling or for other uses.

Two sets of relay contacts are available so that loop and main tracks can be on different blocks.

A 100 ohm resistor must also be included on the terminal blocks (as shown) which causes the loco to slow to a stop and also makes the stopped train still visible to a block detector. This resistor can be changed if not effective. Increase the value if the loco continues to run on and into the turnout.

Manual operation of the points is by a momentary contact (Center off) switch.

Chapter-4a-4 Page 20

Resistor

Color

Codes:

The tolerance band will be Gold for 5% and Brown for 1% resistors Symbol Value Number. 3 band plus tolerance. | 4 band plus tolerance band.

390R 390 Ohms 2 orange-white-brown | orange-white-black-black 1K2 1,200 Ohms 1 brown-red-red | brown-red-black-brown 33K 33,000 Ohms 1 three orange bands | orange-orange-black-red 47K 47,000 Ohms 3 yellow-violet-orange | yellow-violet-black-red 1M0 1,000,000 Ohms 2 brown-black-green | brown-black-black-yellow

Components Resistors, 1 of 47,000 Ohms, 1 of 1megohm, 2 of 33,000 Ohms, 1 of 1,200 Ohms, 2 of 390 ohms

[47K] [1M0] [33K] [1K2] [390R]

1 2N4403 or 2N2907 PNP transistor 1 of 1N4004 diode 3 of 1N4148 diodes 1 of LM556 dual timer IC 2 of 4N35 optical couplers 2 of W04 bridge rectifier Capacitors, 1 of 0.01 ufd, [0,01u] 1 of 0.1 ufd styrene [0.1u] 1 of 1.0 ufd, [1.0u] Electrolytics, 1 of 33ufd at 16 volt working 2 of 100ufd at 16 volt working Relay DPDT 12volt 10amp A 33 hole by 20 hole strip board PCB headers or screw terminals for board connection if wanted 2 of 3 way PCB screw terminals

Tortoise slow motion machines

are fairly universal. Designed To be connected with a plug.

Many are used with the wires directly soldered on - this is a problem if a motor change or shift to another location is required. The correct plug is available from Circuitron.com

Chapter-4e-1 Page 21

A Train Shuttle

A loco and wagons moving along a side track or through a mountain pass can add to the overall effect of a layout. This shuttle controller is simple to setup and install and provides a layout feature point.

Train shuttle operation needs a DC throttle as with DCC power the train direction can not be sensed electrically, nor will a blocking diode stop the train.

However a shuttle could be incorporated within a DCC layout as a separate scene. This circuit is simple and does not allow for intermediate station stops. Speed control (stop and start) is fast as power is cut immediately it enters the stop track or starts up but these areas could be hidden behind other scenery. Speed control is provided by your throttle. If you have grade changes then you could use a throttle with feedback to maintain speed. Because the detection circuit is looking for a loss of track voltage any dirt on the track or loco wheels may cause an unwanted direction change to take place.

While the loco is drawing power from the main track there is a voltage developed across the bridge rectifier in the schematic.

This 1.2 volts activates one of the optical couplers, depending on the train direction. The tied collector outputs are at zero volts while the train is detected and this holds the Schematic and operation: 555 timer at 'reset', When the loco The blocking diodes control the runs onto the stop track no current stopping tracks and will only allow is drawn and the voltage is lost. the loco to move back onto the main line. There is one at each end. The reset (pin 4) is released and the timer trigger 'TR' goes positive

to start the timeout. The timer output at pin 3 goes positive. The capacitors are to filter loco motor and wheel contact noise from the input and provide a delay to the trigger.

At timeout the timer output goes to 0 volts, this turns the transistor on and the positive change at the 'CD4013' flip-flop clock input 'Cp' triggers it. This is a digital circuit and the output at 'Q' will change to the state of the input at 'D' on receiving a clock pulse. This is tied to the inverse output at 'Q/' and so the 'Q' output toggles on and off as each stop track is reached. This changes the state of the relay driver transistor and the relay is either picked or dropped. So every clock input will reverse the direction of the loco. The LED indicates when the timer has been triggered and is timing out.

The timeout delay is controlled by the 2 megohm (2m0) potentiometer and the 4.7 ufd capacitor and can be varied from 9 seconds to 120 seconds with the values shown.

Chapter-4e-2 Page 22

The strip Board or Veroboard as it can be called, is cut to 17 rows by 30 hole size. You could allow a few extra rows top and bottom to make mounting holes. If you do, mask them while you mark the holes to be cut so you see only the 17 rows that will be used this saves confusion and mistakes.

Temporarily number the front and back (copper side) then using the copper side diagram put a spot on the ones to be cut using an ink marker. Note copper side is flipped.

Check carefully twice, as it is too easy to misplace a mark. Check that 41 holes have been marked.

When satisfied twist a No.31 (1/8 inch) drill in each hole to cut away the copper around the hole. Burnish the copper to clean any ragged bits and check with magnifier and/or meter that the copper round each marked hole is fully cut away.

Link wires: I use a single strand insulated wire for the links, like Kynar wire wrap wire. Again mark the holes and

double check before soldering the wires in. Are they correctly related to the cuts on the copper side.

There are 25 wire links. Make sure that you have them correctly placed under the IC's. Another 4 links are to be added on the copper side after the topside soldering is done, shown in green on the component layout.

Component placement: It is best to start with the low profile resistors and diodes first, observe polarity of the diodes. Check each component against adjacent ones, links, etc before soldering.

Add the Integrated circuits next.

You can use sockets for the 4013 and 555 I.C.s which will make it easier to trouble shoot later. Note that the two 4N35's are head to tail as it were. I don't solder pin 3 or 6 of the 4N35 ďž’ s as they are not used although pin 6 is isolated on the copper strip. The capacitors and connectors go on last. Leave the relay and the green link wires until the testing is done.

The connections are shown on PC screw terminals but you could solder wires directly to the PCB if you plan a permanent connection.

Chapter-4e-3 Page 23

Installation:

Prepare the length of track by putting a cut in the same track side at each end, a train length in from the end - plus a bit. Solder a 1N4004 diode across each cut Checking: orientated as shown in the diagram. Solder wires onto the When all is soldered in place get track for the power and run these out the magnifying glass and to the PCB terminals, Tk-a and Tkcarefully check each copper strip b. Connect the CAB to the other forsolder spills over to adjacent terminals and it is ready to go. strips. Running a craft knife blade Mount a loco, switch on the 12 along the gap between the strips volts DC, set the throttle and also helps to locate spillover solder. Use an ohm meter to check something should happen. Cab direction is not important as the that the +12 to Ground terminals do not have a short and that there train will stop at each end track if the diodes are correctly connected. is no short between adjacent copper strips or across the copper Trouble Shooting: strip cuts.

Components: Resistors, 1 of 22 Ohms (22R), 1 of 1,000 Ohms (1K0) 4 of 10,000 Ohms, 2 of 22,000 Ohms (22K) 1 trim potentiometer of 2 megohm (2m0) - this could be mounted off the board for variable timing.

Capacitors, 1 of 4.7 ufd and 2 of 100 mfd at 16 volt 1 of 220 ufd at 16 volt working

3 of 1N4004 diode, 1 of LED indicator 1 of DB155G integrated rectifier 2 of 4N35 optical couplers 1 of LM555 timer IC, 1 of CD4013 cmos IC Apply 12 volt power and check with With no train on the track when you 1 each of transistors 2N2907 and apply the 12 volts the LED should 2N2222 a meter between pins 1 and 8 of the 555 timer chip and 7 and 14 of come on after a few seconds delay 1 12 volt DPCO (DPDT) power relay 5 - 8 amp. the 4013 I.C.s that it is there. Turn (set by the Pot) If it doesn't, the 2m0 Pot fully anticlockwise and measure the voltage at the 555 pin 2 way PCB screw terminals, 3 of Strip board 30 x 17 rows short out pins 4 and 5 of one of the 6. it should be 12 volts or rising toward 12 volts. If 0 volts there is a 4N35 opto couplers. The LED should come on when you release short or open circuit. If above zero but not changing more positive the short, after a short delay and then the 47u capacitor could be this time depends on the pot Bottom view inserted wrong way round. setting. of the green On the 4013 dual flip flop, pin 3 If this is correct then install the link wires. relay and do it again and the relay should be about 0 volts, pins 2 and should click on or off. To finish put 5 at the same voltage and pins 2 Note this is and 3 at opposite voltage. Any the links shown in green, on the an inverted other condition then re-check for copper side of the PCB,. view. copper shorts, wrong link wires etc.

Verify there are link wires under the I.C.

Resistor Color Codes: Symbol Value No. 3 band plus tolerance. 4 band plus tolerance band.

22R 22 Ohms 1 red-red-black red-red-black-gold note a gold multiplier equals times 0.1 1K0 1,000 Ohms 1 brown-black-red brown-black-black-brown 10K 10,000 Ohms 4 brown-black-orange brown-black-black-red 22K 22,000 Ohms 2 red-red-yellow red-red-black-orange 2M0 2,000,000 Ohms 1 red-black-green red-black-black-yellow The tolerance band will be Gold for 5% and Brown for 1% resistors

Chapter-5a Page 24

An Intermediate Signal

Intermediate Signals are located between two Home blocks and are normally a repeater of the Home signal, showing a cautionary aspect if the Home is at stop.

However if you don't have a layout set up with blocks and signaling then this standalone signal may provide some more realism to the scenery between stations.

The signal is two aspect, approach lit, and goes to red as the train passes it, staying Red for a set time period. The circuit is for an Analog or pulsed DC power as it is direction dependent. Circuit operation is initiated when the train passes Spot A, a short isolated rail break some distance back from the signal. This activates a timer which powers the Green LED. When the train reaches Spot B, located beside the signal it changes it to Red and the timer starts timing.

The time period is adjustable, see the table for maximum times. It can be held at Red once triggered by putting a ground to the Hold terminal. The signal can be 2 aspect LED's, Green and Red or a double Tri-LED type searchlight signal.

Timing range with a 100 ufd capacitor is: A 500K trim resistor gives 78 seconds max.

A 1M0 trim resistor gives 132 seconds.

through pin 8. This timer powers up in a reset state and its output pin 3 is at ground. This draws current through R8 and R9 to turn on the transistor and pass current to the green LED. The train bridging Spot B sends a ground to pin 2 of U2 and triggers the second timer. Its pin 3 goes to 12 volts which stops the current to the green LED and supplies a current through the Red LED to ground. U2 pin 7 which was at ground and holding a current to Circuit description.

When the loco wheels bridge the the LED L1 now goes open circuit Option for: and allows the positive voltage rails at Spot A the current 1. Dual LED searchlight signal through the LED to charge the Connect the two LED leads to the activates the LED in the 4N25 timing capacitor through the time R and Retn terminals and connect optical coupler. This causes the output pin 5 to send a ground to adjusting variable resistor. a 1K0 (1000 Ohm) resistor between the G and Retn terminals. trigger the first timer, U1. Its Q Reverse the signal LED leads if the output goes to 10 volts and powers the second timer U2 wrong.colors are shown.

2. Power Control Connect a 12volt DPDT relay and a reversed diode between R and Gnd terminals to control the power on the rail before Spot B. You could use this to space trains that are running on a common CAB. In this case the spot B should be outside the controlled power section or MU'd locos will have to drag the second loco along a dead track.

Chapter 5a-2 Page 25

The time can be set from 2 seconds to more than 2 minutes by selecting and adjusting this control. Note L1 is part of the timimg and not just an indicator.

Construction: Vero Board or strip board as it can be called, is cut to 14 rows by 26 hole size. You could allow a few extra rows top and bottom to make mounting holes. If you do, mask them while you mark the holes to be cut so you see only the 14 rows that will be used. Temporarily number the front and back (copper side) then using the copper side diagram put a spot on the holes to be cut using an ink marker.

Check carefully twice as it too easy to misplace a mark. When satisfied twist a No.32 drill in each hole to cut away the copper round the hole. Burnish the copper to clean any ragged bits and check with magnifier and meter that the copper round each hole is fully cut.

Link wires I use a single strand insulated wire for the links, like Kynar wire wrapping wire. Again mark the holes and double check before soldering the wires in.

There are 17 wire links.

Component placement It is best to start with the low profile resistors and diodes first, observe polarity of the diodes.

Use the wire links as a check for correct component location.

Touch the soldering iron to the copper and the component lead for a second then apply the solder wire to the junction. The solder should melt and run out and along the copper and up the lead a little. Slide the iron up the lead when removing it. This prevents solder from spilling over. Add the Integrated circuits next.

Note that pin 6 of the 4N25s is not soldered and it comes through at a cut location. Some 4N25's have an internal connection to pin 6. The capacitors, LED and connectors go on last. In the picture the outputs are on PC screw type connections and the Spot inputs on 2 pin header plugs.

Checking: When all is soldered in place get out the magnifying glass and carefully check each copper strip for solder spill-over to adjacent strips. Running a craft knife blade along the gap between the strips also helps to locate spill-over solder. Meter the +12 to Ground and check the resistance is high, you could also meter between the copper strips for shorts.

Solder the wires onto them before cutting them loose with a dremal cut-off disk. Make sure they are at the same height as the adjacent rails after this. It does not matter which rail they are on but the connection from the right hand rail (when running toward the signal) should go to the positive marked input pin.

See ‘Short Rail Break’ chapter.

Components

Resistors, 2 of 330 Ohm, [330R] 3 of 1,000 Ohms, [1K0] 1 of 6,800 Ohms, [6K8] 3 of 10,000 Ohms [10K] 1 megohm or 2.2 megohm trim pot Capacitors, - 2 of 0.01ufd Electrolytics 2 of 1u0 at 16v working 1 of 100ufd at16v working Diodes, 1N4148, 1N4004 (2 of) Transistor, 2N4403 NPN Installing: If the signal wires are enameled ICs, LM555N (2), 4N25 (2) copper clean off the ends with 400 Others, LED – red 1 grit sandpaper, mount the signal PC Mount Screw Terminals 6 way, or use 3 of 2 terminals etc. and feed the wires through and Header socket and plug 2way (2) solder to the PC board plug.

Strip board piece Locate where you are going to put 14 rows by 26 holes or to suit.

the Isolated rails for the spot detectors. They should be two sleepers long.

Chapter 5a-3 Page 26

330R 330 Ohms 1K0 1,000 Ohms 6K8 6,800 Ohms 10K 10,000 Ohms

3

2 orange-orange-brown 3 brown-black-red 1 blue-grey-orange brown-black-orange

| orange-orange-black-black | brown-black-black-brown | blue-grey-black-red | brown-black-black-red

Chapter 5B-1 Page 27

Single Line Acquisition Signals Here is a way to control a single line between two loops. Not prototypical but if you have two operators and the loops are not visible to each then the signals will advise if the single track is being used.

How it Works: The first train to cross the detectors, A or B, will claim the line and turn the signals to Red. The circuit uses two 555 timers that are triggered as the train passes over the spot detectors.

Spot A will trigger the top timer in the diagram and it will go into timing mode. However it will not be supplied with timing current until the train passes Spot B and its output (pin 3) goes positive.

Now both timers start timing and when timed out reset each other to show green.

This is unnecessary with DC power as block switching or the CAB direction controls who can use the line.

The signals needed are common cathode. This allows two aspect (separate red and green LEDs) or tri-LEDs (searchlight). The Red leads from both signals connect to the Red terminal, green similarly to the Green terminal. The Red LED drive includes a 270R (270 Ohm) resistor that can be changed to balance the light intensity of the Red and Green LEDs if they are uneven in output. The 560 Ohm (560R) dropping resistors are nominal for 12 volt drive.

When the timer is triggered it can only be reset by the opposite timer being triggered. To stop in the middle and reverse back out would leave the signals at Red until a train passed over the other spot.

The delay is adjustable by selection of C1 and C2 capacitors.

It should be selected so that -

a train running from A to B will fully pass point B before the signal changes to green. If problems are occasionally experienced and the system is not resetting then the 12 volt power could be routed through a push off switch, to force a reset.

The only other requirement is to train the operators to obey the signals.

Link wires: I use a single strand insulated wire for the links, like Kynar wire wrap wire. Again mark the holes and double check before soldering the wires in. Are they correctly related to the cuts on the copper side.

Construction: The strip Board or Veroboard as it There are 18 wire links. Make sure can be called, is cut to 14 rows by that you have them correctly placed under the IC's.

26 hole size. You could allow a few extra rows top and bottom to make mounting holes. If you do, Component placement: It is best to start with the low mask them while you mark the holes to be cut so you see only the profile resistors and diodes first, observe polarity of the diodes.

14 rows that will be used. This Check each component against saves confusion and mistakes.

Temporarily number the front and adjacent ones, back (copper side) then using the links, etc before soldering. copper side diagram put a spot on the ones to be cut using an ink marker.

Check carefully twice, as it is too easy to misplace a mark. Check that 35 holes have been marked.

When satisfied twist a No.31 (1/8 inch) drill in each hole to cut away the copper around the hole.

Burnish the copper to clean any ragged bits and check with magnifier and/or meter that the copper round each marked hole is fully cut away.

Chapter 5B-2 Page 28

Touch the soldering iron to the copper and the component lead for a second then apply the solder wire to the heated junction.

The solder should melt and run out and along the copper and up the lead a little. Slide the iron up the lead when removing it. This prevents solder from spilling over to adjacent copper strips. Add the Integrated circuits next. I don't solder pin 3 or 6 of the 4N25s as they are not used. Some 4N25's have an internal connection to pin 6. The capacitors and connectors go on last.

The outputs are on PC screw terminals and the Spot inputs on 2 pin PCB header plugs.

Chapter 5b-3 Page 29

Spot Detector Options:

Several detection methods can be used. This one, using an optical Installation: coupler, is very reliable and requires no modification to locos or Install the Isolated Track section rolling stock. A reed switch could on the single track just past the be used in place of the optical Checking: turnouts. The single line should be coupler, with magnets on all locos. longer than the longest train that Infra-red, across the track sensing, When all is soldered in place get out you run but there is no limit to total could also be used with appropriate the magnifying glass and carefully length. Once triggered the delays emitter diodes and photo transistor check each copper strip for solder will not start to time out until after detectors. A grounded input is spills over to adjacent strips. the exit spot is crossed. The leads needed to trigger the timers (pin 2) Running a craft knife blade along from the red LEDs go to the ‘Red’ the gap between the strips also helps terminal and the green LEDs to to locate spillover solder.

‘Grn’. The common return from Connect LEDs temporarily to the each goes to the terminals, return-1 screw terminals. and 2 (Retn).

Apply 12 volt power and check with a meter between pins 1 and 8 of the Bulb Signals Option: timer chips that it is there. To activate the circuit without it being To use signals with bulbs add a connected to the track short the small 5 volt PCB relay, connected 4N25 pins 4 and 5 which simulates a between the Red output and train crossing the detector strip. ground.

Wire the signal lamps to the change over contacts .

Timing Capacitor Options C1 and C2 10 ufd gives 15 seconds, 22 ufd 34 seconds,.

33 ufd 51 seconds, 47 ufd 75 seconds, 100 ufd 155 seconds, Or (2min 35 seconds)

Block

Signaling

Chapter 5b-4 Page 30

Components Resistors: 2 of 1,200 Ohms, [1K2] 3 of 10,000 Ohms, [10K] 2 of 1 megohm, [1M0] 2 of 560 Ohm , [560R] 1 of 270 Ohm, [270R]

Capacitors: 1 of 0.1ufd, 2 of 0.22ufd Electrolytic, 100ufd 25volt working.

Optional electros: 10, 22, 33, 47ufd. - See Table.

Strip board 26 x 14 rows

Resistor Symbol Value

system

This could be part of a signaling system. It will work on single or double tracks between stations or loops. Each block of single track has 2 signals at the start of the block, one in each direction. These control the entry into the block. If there is already a train in the block then the entry signal is Red at both ends. When the block is clear both signals are Green.

On double track only one signal is needed to control the entry into the block. There is no interlocking or power control in the system and operators need to drive on the signals

Semiconductors: 5 of 1N4004 diode , 2N4403 PNP transistor, 2 of 'W04' Bridge Rectifier, 2 of 4N25 optical coupler, 2 of LM555N timer I.C. 2 of 2 pin PC Connector, 6 way PC terminals

Color No.

3 band plus tolerance.

270R 270 Ohms 560R 560 Ohms 1K2 1,200 Ohms 10K 10,000 Ohms 1M0 1,000,000 Ohms 2

1 2 2 3

Codes 4 band plus tolerance band.

red-violet-brown green-blue-brown brown-red-red brown-black-orange brown-black-green

The tolerance band will be Gold for 5% and Brown for 1% resistors

red-violet-black-black green-blue-black-black brown-red-black-brown brown-black-blackredbrown-black-black-yellow

Chapter 5c-1 Page 31

Flashing Signal Aspects Some signal light aspects are steady and some are flashing. Why?

Well, by making one of the lights flash it is effectively adding a 4th aspect to a three lamp head. The most common is an advance approach light (Yellow flashing) and this informs the engineer that the second signal ahead is at Red and speed must be reduced to enable a complete stop. Necessary in these days of long heavy trains. While a flashing divergent advance approach would indicate a turnout ahead and to be prepared to stop at the second signal. In some systems it can indicate that the train is approaching an area (junction/loop etc.) where the approach normal speed is changed to an approach limited (higher) speed. I would expect there to be a set of high speed turnouts ahead. A Red flashing or Marker board flashing allows a proceed at reduced speed which over-rides the stop and stay condition of a normal Red aspect.

I can find no real information on dwarf signals flashing but as they are usually only 2 aspect it perhaps doesn't apply although I believe SP flashed Green under some conditions.

Interestingly in the United Kingdom a flashing yellow would indicate that a train is to take a diverging route ahead with a lower line speed than the main route, indicating to the driver to slow the train down in time for the speed limit of the diverging route as opposed to slowing even more in preparation for a stop signal.

The micro switch shown in the schematics would typically be connected to a turnout throw bar or possibly be a block detector relay.

Reference these web sites for more signaling information :http://www.railroadsignals.us/ - for a reference to Color Position Lights. http://www.davros.org/rail/signalling/articles/junctions.html - U.K. systems http://www.railroadsignals.us/rulebooks/rulebooks.htm from a selection of railroads

What circuit do I use ?

If your signals have a common wire that is positive - use PNP If the common wire is negative or ground - use NPN But not on signals with a common dropping resistor in the signal.

The Green Flashing LED This 5mm diameter device contains an IC oscillator circuit in series with an LED. This allows it to be driven from a very wide voltage range from 3 to 15VDC without any external components required. The LED itself produces a bright output of 500mcd (typical) making it suitable as a very notice ďž­ able warning lamp in alarm panels, car and boat dash boards, etc even in daylight The series 6K8 ohm resistor reduces the brightness as it is not being used as an indicator in this circuit.

Chapter-5c-2 Page 32 LED signals come in several configurations.

The Common Anode type has all the positive LED leads connected and they will be wired to the 12v (or positive source). This could be via a common dropping resistor.

The Common Cathode type has all the negative leads connected and wired to ground (negative voltage) or could have a common dropping resistor that is wired to ground.

Other types are less common but there can be signals where all the LED connections are individually made. There will be 6 wires going to the signal.

Using a common dropping resistor is an acceptable practice, but LED's of different color have a different brilliance and an individual dropping resistor for each LED is preferable, especially if they are run at a lower intensity for more realism.

They can be used on 4 aspect (2 yellow) signal heads where both yellows may be flashing together.There is one circuit to be used with common anode (PNP) and another for common cathode (NPN) signal systems.

Both circuits do the same thing but with reversed polarities. The LED is activated by the signal control system as normal and then when the ‘flash’ switch is on, the flashing LED will activate and turn on the transistor which shorts out the LED so it is extinguished. The flash rate is controlled by the flashing LED part of the circuit and is not adjustable. They are spec'd as between a 0.5 second and 2 seconds period.

Components, 1 x 5mm Flashing LED, (any color) Transistor NPN 2N2222A or PNP 2N4403 Resistors, 6,800 (6K8) Ohm 2,200 (2K2) Ohm 220 (220R) Ohm

Construction:Note the copper track is cut at position row 1, hole 6 ( X on the diagram) The 8 by 11 hole PCB could be expanded to allow for plugs to be installed.

In fact you could make the PCB by cutting and drilling a blank piece of copper clad board into 8 strips with row one cut in the middle. Drill 1mm (#60) holes where needed.

Mount the components and solder. Note the LED is polarized, get the "+" (longer lead) in the right place or it will destroy when powered on.

The transistor leads need to be spread a little so that the emitter is one hole away from the base lead.

The 220R resistor is connected to the signal to be controlled. The GR-Y positions shown can be altered so that if the Green is to be controlled then it is wired down row 5. It would even be possible to have two aspects flashing by putting a second resistor from the transistor collector to another signal line. Either would be flashed depending on which was active. Or if a two yellow (4 aspect) head then both yellow lines could be controlled as they would both be active at the same time.

Installation: The circuit to control a 3 aspect LED signal is inserted into the 4 wires running to the signal head.

A 5th wire and switch for a control voltage is added to turn on the flashing aspect when required. If the flash is not activated the signal LED works as normal. The switch could be manual, a microswitch actuated by the turnout position or a control voltage sent from the signaling system.

The circuit may be used to control any of the aspects as required.

NOTE: These 2 circuits are for use with common anode or cathode types that have individual dropping resistors for each LED. Attempting to use the circuit on a signal with a common internal dropping resistor will destroy the transistor and damage it

Chapter-5d-1 Page 33

Crossing Lights Here is a simple design to provide flashing crossing lights on a single track for trains going in either direction.

The circuit is similar to that of "An If it stops and reverses over the Intermediate Signal" and basically entry point the sequence is not detects the train entering and completed and the lights will exiting the area between the two continue going until the exit spot detectors. When a train is detect point is crossed. detected the circuit activates a set of alternately flashing LEDs on the The circuit will work on a double track but if two trains are in the crossing signs. The flash rate is detected area together the controlled by a Flashing LED. sequence will probably not be When ON it pulls power through two of the crossing LEDs and when correct. it turns off a transistor switches on and pulls power through the other How it works: two LEDs. The two timer circuits work Installing the spot detectors, called Entry and Exit, will need some thought. The spot detectors should be located an equal distance either side of the crossing. The distance being far enough away so that the last wagon of the longest consist just clears the crossing when the train has passed the exit detector.

Use your longest consist running at its normal speed. Single locos or shorter consists can't be controlled so closely but most observer attention will be as the train approaches and the lights start up so any extended flashing after the train passes may not be significant.

This is only a simple logic and the train is expected to pass the entry detector point then exit past the other detect point.

interactively. Either spot detector can start the sequence and the opposite one will finish it. After the exit detector is crossed there is a delay, about 5 seconds to allow a multiple loco consist the get over the detect points. Any crossing made-

after this time would be taken as another sequence being started .

The timer that is triggered first cannot time out until the other one is triggered by the train crossing the exit detector. Then both time out in the delay time set by the 2.2 ufd capacitor and the 1.0 meg-ohm resistor.

Either timer being on will activate the flashing LED and the lights.

The flashing LED is not symmetrical, on to off times, so a 100 ufd capacitor has been added to even it up.



Chapter-5d-2 Page 34

Construction: The strip board is cut to a 16 row by 27 hole size. Temporarily number the front and back (copper side) then using the copper side diagram (below) put a spot on the ones (X marked) to be cut using an ink marker.

Check carefully, twice, as it is too easy to misplace a mark. Check that 35 holes have been marked.

When satisfied twist a No.31 drill in each hole to cut away the copper round the hole. Burnish the copper to clean any ragged bits and check with magnifier and/or meter that the copper round each marked hole is fully cut.

Link wires: I use a single strand insulated wire for the links like Kynar wire wrap wire. Again mark the holes and double check before soldering the wires in. There are 19 wire links.

Make sure that you have them correctly placed under the IC's.

Components: It is best to start with the low profile resistors and diodes first, observe polarity of the diodes. Check each component against adjacent ones, links, etc before soldering. Add the Integrated circuits next. I don't solder pin 3 or 6 of the 4N25s as they are not used. Some 4N25's have an internal connection to pin 6. The capacitors and connectors go on last. The outputs are on PC screw terminals and the Spot inputs on 2 pin plugs.

Checking: When all is soldered in place get out the magnifying glass and carefully check each copper strip for solder spillover to adjacent strips. Running a craft knife blade along the gap between the strips also helps to locate spillover solder.

Installation: Cut the Isolated Track sections where you have calculated. Both spots are identical in connection. Once triggered the delays will not time out until 5 seconds after the exit spot is crossed.

The positive leads from the LEDs go to the Sig-1 and Sig-2 terminals.

The return from each pair goes to the terminals Retn-1 and Retn-2. .

To wire for double track make the two detector rail sections on each side of the crossing common, ie they are wired together. The both sets of rails must be in the same power block and on the same power buss. Test with a meter if not certain.

However if two trains pass on the crossing section then the logic will be confused and the light etc. will not work as expected

Option 1: This could be used to control a servo circuit, described later, to raise and lower crossing arms. A signal is produced at the "Sw" and "Gnd" terminals that should be wired to the same named terminals on the servo driver.

The terminals could be a 3 pin PCB Header or just wires soldered in.

Option 2: A small buzzer can be inserted into the LED circuit as shown on the schematic to make a soft repeating sound that is a little bit like the electronic crossing chime now in use. It should be soft enough to be heard for only a few feet from the crossing.

Connect it in series with the cathode return wire going to the terminal Retn-2

Chapter-5d-3 Page 35

Components: Resistors: 2K2 - 2, 10K - 2, 1m0 - 2, 470R - 2, 560R - 2, 56K - 1.

Other: 1N4004 diode - 2, 2N2222A NPN transistor - 2 Capacitors: 0.1ufd, 0.22ufd - 2, of, 2.2ufd electrolytic 25volt - 2.

'W04' Bridge Rectifier - 2, 100ufd electrolytic 25volt - 2. 4N25 optical coupler - 2, LM555N timer IC - 2.

PC header Connector - 2 and 5mm Flashing LED 3-12 volt 3 pin as required.

Strip (Vero) board 27 holes x 16 rows

Components for buzzer option: Resistors, 150 and 390 Ohms, Capacitor, 1000 ufd 16 volt working Diode 1N4004 1.5 volt piezo buzzer.

Resistor Color Codes Symbol Value No. 150R 150 Ohms 1 390R 390 Ohms 1 470R 470 Ohms 2 560R 560 Ohms 2 2K2 2,200 Ohms 2 10K 10,000 Ohms 2 56K 56,000 Ohms 1 1M0 1,000,000 Ohms 2

3 band plus tolerance brown-green-brown orange-white-brown yellow-violet-brown green-blue-brown red-red-red brown-black-orange green-blue-orange brown-black-green

4 band plus tolerance brown-green-black-black orange-white-black-black yellow-violet-black-black green-blue-black-black red-red-black-brown brown-black-black-red green-blue--black-red brown-black-black-yellow

Chapter-6a-1 Page 36

A Motor Speed Control

This is a simple motor control circuit. It has good starting characteristics and it will run at a slow speed. It could be used for a loco motor, turntable drive motor, accessory equipment such as cranes, winches, etc. Use it for a single direction motor or with a change over switch, bi- direction control. It can be powered by an AC plugpack (Wall Wart) of 14 to 16 volts AC or a transformer. With the pulsing DC developed from the AC input it has good start and slow running characteristics and it is gentle enough to be used with all types of motors. There is some feed-back from the motor that will increase the drive voltage if a heavier load is encountered. The power source selected should have enough voltage and amperage to match the motor. The circuit components can be altered to suit the motor. It is not a precise controller and the speed will vary slightly as the transistor heats up, so a heat sink is essential.

With the speed control at minimum (to the right hand side on the diagram) there is still a trickle of voltage being supplied to the motor which, if it is in a loco, will 'tickle' a block detector or if driving a turntable, it can be used to bias the motor and hold it onto the stop at the selected track position.

The transistor used is a Darlington type which gives a high power output for low base drive current.

As it has to absorb the surplus voltage not used by the motor it can get warm and a heatsink is needed.

The bridge rectifier gives a full wave rectification and the voltage out of it goes from zero volts to about 19 volts and back to zero at twice the -

Components mains frequency (120 times per second in the USA) This gives an average voltage of about 16 volts.

The zener diode limits this to a zero to 12 volt pulsing wave. With the potentiometer 'off' there is a small current through the resistors and diode to the motor.

Not enough to run it, but it could be used to hold the motor against a stop. The potentiometer resistance can be changed to adjust this bias power, 500 ohms gives about 1 volt, 100 ohms about 3 volts. When the speed control is moved off 'Low' the transistor starts conducting and it supplies a higher voltage to the motor and starts it. The voltage to the motor can go as high as the zener diode regulated voltage value.

One resistor of 100 ohms at 1 watt, Potentiometer with PCB mounting of 500 ohms, ďž˝ to 1 watt, a 2 to 4 amp bridge rectifier, W06 a 12 volt 1 watt zener diode (depending on the motor running voltage needed), a 1 amp diode type 1N4004, Darlington transistor BD681 for motors to 1.5 amp and TIP141 for up to 3 amp power.

A Heat sink to suit the transistor that has a screw or solder mount to secure it to the 18 by 13 hole veroboard (resize if necessary to suit the heatsink)

Chapter 6a-2 Page 37

The PCB has a socket for the plug-pack lead.

Chapter-6h-1 Page 38

Servo Driver

Trains are not the only things that move in the real life scene. How does your model look?, great scenes but nothing moves? That ďž’ s not too hard to remedy.

Radio Control sets use a specialized servo that gives a 180 degree movement on command of a control pulse. It can easily be linked to things we want to move on the layout, road crossing arms, turnout motors, loco shed doors, turn tables to mention a few.

A servo is a geared motor whose output wheel or arm can be accurately positioned by a command pulse. The pulse is sent at regular intervals and the servo will hold its rotation position. The pulse width range is 1 millisecond to 2 milliseconds at about 16 to 20 milliseconds interval. The motors are small and due to the reduction gearing have a good torque. The output wheel or shaft can travel about 200 degrees.

This circuit will generate 2 control pulses depending on a switch position. The two control pulse values can be adjusted to set the rotation required. Servo movement speed depends on the servo but usually is fairly fast.

Servo mechanisms are varied, at present there is a range in price from $6 to $20.

Quality of movement varies, cheaper ones will have less accurate positioning and perhaps some overshoot. I have not tested all of them but most will be suitable.

most will change servos yearly to avoid flight failures.

There are even servos with a linear movement instead of the usual rotary type. The only minus with the motors is that they run on 5/6 volts so a small regulator has to be included in the circuit if you plan to run on a 9 to 15 volt supply.

The circuit is controlled by a ground level.

This can be from a toggle switch or a grounded input from another circuit. This picks the relay to change the discharge current path for the timing capacitor. The charge time (pulse off time) is fixed at about 16 to 20 milliseconds which is standard for the servos. The 5 volt power for the servo comes from an IC 5 volt regulator which needs a 9 to 15 volt input. The timer output voltage is the opposite to that required by the servo so a transistor is used to invert the pulse.

Turning the trim potentiometer clockwise increases the pulse length. The pulse is variable from 0.9 milliseconds to 2.5 ms.

Although these are the extreme limits of the servo movement and it may chatter the motor, back off a little if this occurs as it can soon overheat the regulator. For You don't need the high output power type the normal range of 1 ms to 2 ms the unless you plan to lift/move a heavy weight servo will rotate about 180 degrees. and then the power required may exceed the Often the 2 ms can be stretched toward current capabilities of the circuit. If you know 2.5 ms to get slightly more rotation. anyone who is into competition RC Aircraft flying have a talk to them about second hand servos as

Options for the circuit.

1. The relay can be left out, solder across cuts at 6/21, 8/21, 10/21 wire a change over switch to NO-Com-NC terminals if you are reasonably close to the PCB position. The turnouts in a yard might be one use for this option.

2. One of the adjusting Potentiometers could be replaced with a resistor (4K3 value) if you do not need to adjust one end of the movement.

3. Leave out the relay, connect the Common and normally closed contacts together (8/19, 10/19) and use a remote 5K0 potentiometer for P1, located off the PCB to give a continuously variable pulse and servo rotation.

4. A second servo PCB without the regulator could use the 5 volts and ground from this one (row 4 and 5 have 5v and 0v on them) and link these to the second PCB. The second set of change over relay contacts is available for crossing lights, lamps, signals, sounds etc..

This is a simple circuit. More complex ones can be found to let you also control the speed that the servo moves between the two

Chapter-6h-2 Page 39

Construction: Cut the Strip board to size, 25 holes along the copper row and 15 rows high. A bit more if you want to include mounting screws but mask off the extra holes so you are not confused when marking for the cuts and installing links. Clean and burnish the copper strips so they solder easily. Now on the copper side mark the positions of the holes to be cut. The diagram shows the view on the copper side. Double check the marks and then twist a #32 drill bit in the hole so the copper strip is cut right through. Examine with magnifier or meter them to ensure they are fully cut.

Turn the board over and install the vertical link wires, use a thin single strand covered wire, I found kynar covered wire-wrap wire good for this. As you insert and solder the wires double check the position against the cut holes to avoid mistakes.

There are 15 link wires and 3 positions where a wire has to be soldered across the copper strips, shown RED on the diagram at row 3/12, row 13/19 and 13/22.

When soldering, put the bit against the copper and the component lead and after one second touch the solder to the joint. The solder should spread along the copper and wick up the lead. Pull the bit up the lead as you remove the soldering iron to avoid spill onto adjacent strips.

Now the diodes (check position) and resistors can be soldered in.

Then the LM555 and trim potentiometers (Pot) Lastly all the larger components.

The miniature type of relay used has two possible contact orientations, check the side of it for a diagram or use a meter to verify which pin is which.

They may have the common at the center of the three pins (as in the diagram) or at the first of the three. You will have to change the wiring as in the smaller vero-2 diagram if it is the second type.

To finish do a visual check against the vero diagram, turn the board over and run a hobby knife blade along the rows between the copper strips to make sure there are no solder bridges between them and examine closely with a magnifier to ensure all joints are soldered.

The servo will need a matching socket to connect it to the terminals on the board.

Connect a switch or use a bridging wire for the 'Sw Gnd' terminals while testing.

Move the Pots to about center position and apply power. The servo should move a little or buzz. If not remove power, change the Pot position about

1/4 turn and apply power again. If there is no movement then you will have to find the reason by double checking everything again. At this stage get expert help.

Installation: The installation required will vary but ensure the Servo is firmly secured, it should not overdrive the mechanism's end stops as this will rock the servo mounting and may destroy it.

Note that cheaper servos may have some overdrive before they settle to the correct position. Using the rubber grommets on the servo mounts will allow a little bit of flexibility in the movement, as done in aircraft mountings. Or you could use a spring loaded link that will allow overshooting a fixed stop. Adjust the Pots until you get the required movement.

Start with the Pots about center and adjust from there.

Which one and the position they control is up to you.

Chapter-6h-3 Page 40

Servo for Radio Control Wires to the main board RC servos are an electric motor mechanically linked to a potentiometer. Signal pulses sent to the servo are decoded into a voltage by the electronics in the servo. The servo motor potentiometer produces a voltage proportional to its rotated position.

If this is different to the decoded voltage from the input pulse then the motor is supplied with power to correct the position.

The servo interface is three wires: ground (black), power (red) and control (brown/white). The servo expects a pulse every 16 to 20 ms or it may lose position.

A servo pulse of 1.5 ms width sets the servo to its "center" position. In general the servo's angular rotation will be somewhere in the range of 180° to 210° for a minimum pulse of 1.0 ms and maximum of 2.0 ms.

Internally the servo has two parts, the gears and potentiometer above and electronics below. The electronics are miniature components and are not repairable. By removing the limit on the drive gear and the drive to the potentiometer, then locking the potentiometer in its central position the servo will become a variable speed motor, depending on the pulse width. Rotation direction depends on the pulse being above or below the central position.

Components: This is a popular make of medium sized servo. It is supplied with a variety of ‘wheels’ and ‘horns’ This one has a long arm fitted which will give a large 180 degree rotary movement. There are four mounting holes on the top flange, and the rubber grommets, screws and washers for mounting are supplied.

The lower picture shows the gear train of an older make of servo.

The gears are covered by the case and only the square shaft sticks out. The wheel or arm screws onto that. The final drive gear can be metal for better wear. The potentiometer is directly below the drive gear and driven by it so there is no back lash

Resistors, all 1/6 or 1/4 watt.

2 of 3300 Ohms, [3K3] 2 of 10,000 Ohms [10K] 2 of 100,000 Ohms, [100K] Capacitors, 0.1ufd, 0.22ufd plastic, electrolytic at 16 volts, 1 of 100ufd Diodes, one each of 1N4148 and 1N4004 Transistor 2N2222A, 2N3904, BC547 or any utility NPN type Timer IC LM555, NE555, 7555 all are suitable Relay Small PCB type DPDT at 5 volts. See note on which type.

Regulator LM7805 or equivalent.

Potentiometer, PCB mount, 2 of 5,000 Ohms, [5K0] Screw PCB mount terminal strips, 2 of 2 way and 2 of 3 way, or as required.

Matching servo cable socket.

Stripboard 25 holes by 15 rows.

Resistor Color Codes Symbol Value No. 3K3 3,300 Ohms 2 10K 10,000 Ohms 1 100K 100,000 Ohms 1

3 band plus tolerance. orange-orange-red brown-black-orange brown-black-yellow

4 band plus tolerance band. orange-orange-black-brown brown-black-black-red brown-black-black-orange

Chapter-6j-1 Page 41

Carriage Lighting

If you run a night time scene and have people in the carriages then why not provide lights for them This is easy to organize with DCC power as the track voltage is always there. Power is picked up from the bogie Wheel-set. The simplest pickup is a phosphor bronze wire rubbing on the axles, when only one wheel is insulated.

Inset is an Athern bogie set with plastic body and only one wheel on each axle is insulated. The front bogie picks up from one rail, the rear from the other.

Components:

Depending on the DCC voltage 6 or 8 white LEDs can be powered per carriage. If you are doing a multi carriage consist, then consider running a pluggable wire along the consist to connect together all the pickups to give flicker free lighting.

The circuit is very simple. The positive going DCC pulse feeds the regulator LM317 which supplies a constant current through the string of LEDs. Two strings can be fed from the regulator. The current and therefore the brilliance of the lights can be controlled by changing the 330R resistor. A higher resistor value gives less brightness. Each LED will drop 2 to 3 volts depending on the current. The regulator needs

Resistors, 2 of 10 Ohms, [10R] 1 of 330 Ohms, [330R] Capacitor, 0.1 ufd LM317 IC Regulator X marks a LM317L for N scale copper strip Strip board to suit and white LEDs

cut about 3 volts to operate therefore if your DCC voltage is set to 12 volts then only 3 LEDs can be driven in each string.

The PC board can be glued or taped to the inside roof of the carriage and 2 wires dropped down to the pickups. The strip to hold the LEDs can be cut from strip board, 2 holes wide for strength, and the LEDs soldered along it. Remember to cut the copper under each LED. LED life is a function of the current applied and LED quality.

If you run N scale carriages you can make your own board. Scribe through the copper on a thin plain laminate board that is about half the size of the strip board and drill it to accept the components. Using the smallest possible components a very small board can be made that will fit under the roof. The 10 ohm resistors in this case are mounted off the board. Either in the leads (as the picture) or in the string with the LEDs. The regulator is the smaller LM317L which is low power and can only handle 100ma. The LEDs will only draw 20 to 30ma in each string so will not overload it.

Tiny N Scale board – top and bottom..