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Talking Electronics has produced two books on Model Railway Electronics.
They are Electronics for
Model Railways-1 (pdf) and Electronics for Model Railways-2
(pdf)
These books have completely sold out so we have provided them in .doc
format (Word) and .pdf
All the kits from the two books are still available and we get lots of orders,
but you must make sure
you are good at soldering and see what the module does, before ordering.
Some of the modules are available fully assembled and tested and some
have been improved or simplified
and you need to contact us before ordering anything.
Electronics for
Model Railways-1 .pdf
(35MB) free
Electronics for
Model Railways-1 .doc
(13MB) free
Electronics for Model Railways-2 .pdf (56MB)
free
Electronics for Model Railways-2 .doc (13MB)
free
For a list of every electronic symbol, see:
Circuit Symbols.
For more articles and projects for the hobbyist: see TALKING ELECTRONICS WEBSITE
email Colin Mitchell:
talking@tpg.com.au
More than 24 CIRCUITS as of 12-8-2019
Talking Electronics website has the remaining 50 projects as
kits
and the instructions are available in the two books shown above. As well as more projects
on the website.
INTRODUCTION This e-book presents a lot of interesting projects for Model Railways. Talking Electronics has produced two books for Model Railway enthusiasts (book-2 is now out of print). The two books are: Electronics for Model Railways-1 Electronics for Model Railways-2 Since releasing these two books, we have designed lots of extra projects and more are being released all the time. There is a very large group of Model Railway enthusiasts in the world and nearly everyone's layout includes more and more electronic devices, modules and controllers. But a lot of enthusiasts are not electronically attuned and have either not studied electronics or had the fortune to have built electronic projects. That's why many of the projects we have designed recently are available as a kit or already built and tested. Even to put a kit together you have to be able to identify each part and fit it correctly as well as owning a fine tipped soldering iron and knowing how to solder quickly and cleanly to prevent overheating the component. Most Model Railway magazines don't have circuits and projects you can build, mainly because they don't have the back-up of component suppliers, reliable kit suppliers or the staff needed to answer questions on fixing kits that don't work. We have all these features at TALKING ELECTRONICS and everything is backed by emails and service. Most emails from us are very short as we have hundreds of emails to attend to each week but you must reply with one question at a time and eventually your problem will be solved. Colin Mitchell If you have DCC
Digital Command Control on your model railway, or are thinking about
using it or starting a layout with this feature, here is a website
dedicated to helping you:
Digital Command Control is a standard for a system to operate model railways
so that two or more locomotives can be controlled independently on the same
section of track. |
NOTE: Many of the projects and circuit and ideas in this eBook are available from Talking Electronics as complete kits, fully assembled, or as components at very low prices. Talking Electronics has sold over 300,000 kits during the past 40 years and about 100,000 have been Model Railway kits. You can now get many of the kits fully assembled and tested for those who have a layout but not a soldiering iron. Many of the projects are so new and different and complex that you will not understand them fully. Email: Colin Mitchell and ask for assistance before buying or doing anything. Here are some wonderful layouts and videos taken from the front and back of the trains on the layouts . . . . from MODEL RAILWAY LAYOUTS PLANS.com http://modelrailwaylayoutsplans.com/dave-tidies-up-his-layout/?inf_contact_key=93a9574ff8f6930e95fe40eaba006a971b0a3f0fd3ee5d9b43fb34c6613498d7" Video: https://youtu.be/MnBfqBCWNp4 You must join: MODEL RAILWAY LAYOUTS PLANS.com because they send a new layout every day with videos. This link show the enormous amount of wiring required for a layout with points and signals. This is the latest: http://modelrailwaylayoutsplans.com/john-shows-us-more-of-his-stunning-layout/?inf_contact_key=d02020000d3e42e28f99cc8a315cea07d18a532c4142cb79caf2b269de1401fa
Here are 2 of the latest images: There are 200 more photos of layouts on the
website:
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Every project needs POWER. Power is ENERGY (actually: Power over a
period of TIME is energy) and it comes from a
battery or a POWER SUPPLY.
Power supplies are also called wall warts, plug packs,
chargers or adaptors and must be of the type that is SAFE. In other
words, you must be able to touch the output wires and the tap in the
kitchen and not get killed. USING DC ADAPTORS IN PARALLEL
USING
AC ADAPTORS IN PARALLEL
USING
DC ADAPTORS IN SERIES
You can connect any TWO or THREE together and the output voltage
will be the sum of all the voltages and the current will be
determined by the lowest current of the 3 adapters. If you do not have any old Plug Packs, you can buy new ones on eBay
for a few dollars.
THE BEST ADAPTOR:
The best DC adapter for all the CDU modules is a 24v or 30v supply
made from two 12v adaptors in series of three 10v adaptors in
series.
The $2.50 plug Pack above was purchased as 12v @ 1 amp. It was
easily opened-up via a screw and clip, to reveal the PC board shown
below.
Some of the CDU projects can be supplied with 30v to 36v DC to fully charge the electrolytic(s). You can make a 36v supply very cheaply by using 24v and 12v plug packs and these are available on eBay for less than $10.00 (for both) including postage. Simply connect the leads as shown in the following diagram to get 36v. Some of these plug packs have a current detecting overload circuit and "shut-down" if the current is more than 1 amp (even for a millisecond). To prevent this we add a 47 ohm resistor. This "trick" only applies when you are using the plug packs for our CDU modules as the high current is only required for a few seconds and then falls to a very low value and the resistor will not get warm when used for this particular application.
THE ALTERNATIVE TO A WALL WORTBecause a Wall Wort producing 13v AC or 27v DC is fairly difficult to obtain (almost impossible) Talking Electronics has produced a number of CDU modules that accept almost any voltage (AC or DC or DCC) from 9v to 15v (either AC or DC) and the on-board voltage generating circuit will produce an output of exactly 27v DC. The latest module to have this feature is JIM's CDU MkII and it has a mini trim pot to adjust the output voltage from 13v to 27v DC to cater for all different types of solenoid points. This module has on-board push-switches to control the position of the point and each module is designed to be connected to a single point or two or three points that ALL need to be activated AT THE SAME TIME. You can see the project HERE. This is just one way to get around the problem for the moment, but at some point in your plans to produce a large layout, you will need a POWER SUPPLY. You can spend a lot of money on a POWER SUPPLY but Talking Electronics is always aiming to show the cheapest and best way to get something at the lowest cost. Let's look at what we are talking about:
BENCH POWER SUPPLY
They come in all sorts of arrangements and offer current
limiting and output voltages from 0v to 35v (or higher) at 1 amp to 10 Amp or more. Power Supply MkII
The following project is a 0v to 12v BENCH POWER SUPPLY with current
limiting and has an output of 1 amp. This is sufficient for all types of
testing and you can increase the values by referring to the circuit. This is the cheapest,
safest Power Supply you can get.
Here is a set of 4 Li-ion cells. Just use the 4 lower cells in a 4-cell carrier. The top cell is just to increase the voltage slightly so the project will produce slightly more than 12v at 1 amp.
The 4-cell carrier can be bought on eBay for about
$2.50
The charger below will charge a single cell at about 500mA to 700mA and connects to your USB port on a laptop. You can only charge one cell at a time with this arrangement.
The 1 ohm resistor will discharge the cell quickly. The cell voltage
must not go below a minimum voltage of
2.8v. You need to place a voltmeter across the resistor while
discharging to make sure you do not discharge the cell below its
recommended minimum. The module in the photo charges the
cell quite quickly and at 4.2v the cell is charged to 90% (or more)
and the circuit turns OFF. More details of the project shown above can be found HERE. It describes a 1 amp adjustable POWER SUPPLY that can be used to power your locos or as a BENCH POWER SUPPLY for all your testing.
CURRENT A small loco takes 300mA to 600mA and you need a 1AMP supply to make sure the necessary current can be supplied as the motor will take 800mA to 900mA when starting and accelerating and when hauling a number of coaches. For a DC layout, you will generally only be running one loco at a time and a 1-Amp supply will be sufficient. The current values mentioned above apply when the supply is 12v. If the supply drops to say 10v, the current will be less and if the supply increases to 14v, the current will increase by a considerable amount (when the same motor is connected). It is impossible to state the actual values because the current taken by a motor increases and decreases due to the load and this load is not only the velocity of the train, but the acceleration and inclination of the track and also the rpm of the motor (as it takes more energy to rotate at higher rpm) and lots more current when the motor is "loaded." AC TO DC Before we finish, there is a bit of theory that needs to be understood. We have mentioned the AC voltage and DC voltage on (or for) many of the projects. The two values are a little bit different and you may be wondering why. The technical reason is this: When you deliver 10v AC to a circuit that has diodes and capacitors (electrolytics) that convert the voltage to DC, the output is 40% higher than "10" because the 10v AC is actually 14v at the instant when the voltage is rising to a maximum and the capacitors get charged to this value. There is a loss of about 1.5v across the diodes in the circuit and the output becomes 12.5v Quite often the manufacturer of the 10v AC transformer will add a few extra turns and the voltage will be 13v AC (under no load). This is done because the output drops when full current is delivered (because the transformer is very poor quality) and this will ensure the output never goes below 10v AC. It drops from 13v to 10v - under full load. However the 13v AC will produce 18.2v AC minus 1.5v = 16.7v DC when unloaded and if you deliver more than 13v AC, the resulting unloaded voltage may be too high for some of the electronic components - especially IC's.
CONCLUSION |
This is PART "A" of our
discussion on controlling a point.
A Point Controller is a "device" or "MOTOR" or "SOLENOID" that
changes the point from "ahead" to "Siding." All layouts
need a point or lots of points so you can make
an impressive layout and have the trains leave and enter the main line
and provide shunting yards and loops and interconnecting lines.
If you have a solenoid operated point, we will cover
it later:
We connect a motor and worm gearbox as shown in the following image to the actuating lever on the point:
Image shows
the control rod on the gearbox is
The following image is the module that controls and limits the motor's operation. It allows the motor to be connected to a 9v to 16v AC or DC supply.
You get a micro motor with worm
gearbox and module and DPDT push-push switch
and the position of the point is shown on the red and green LEDs on
the module.
The movement of the point is fairly rapid. There are other modules
with slow movement.
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CHOICE NUMBER 2:
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NUMBER 3: ![]() The Printed Circuit Board has 2 x 500R mini trim pots to adjust the amount of travel of the output arm.
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CHOICE NUMBER 5:
Click Here
to order. oooooooooooooo0000000000000000000000000000oooooooooooooooo
CHOICE NUMBER 6:
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CHOICE NUMBER 7: The on-board tactile buttons need to be pressed for about 1/2 second for the program to recognise the button and activate the servo to set the point to the correct position. You need to set each point so that the PC board reflects the correct position of the point. Do this will all 5 points and you are ready to drive the loco. oooooooooooooo0000000000000000000000000000oooooooooooooooo SUMMARY |
This is PART "B" of our
discussion on controlling a point. (see PART "A" to control a point with a motor) The most common type of point motor is a solenoid that moves the rails from one position to the other. It is also called a TURN-OUT MOTOR:
It must be activated for less than 1 second. It was activated for 4 seconds and it MELTED !! The plastic core melted and bubbled through the coil and the activating rod is FROZEN. That's what this article is all about. If you add a CDU module to activate these POINT MOTORS they will not get damaged.
The SOLENOID Point Motor consists of two
coils of wire that alternately pull a metal rod into the middle of the solenoid and
at the same time change the position of the point.
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CHOICE
NUMBER 8:
The screw terminals make it easy to fit to your layout.
touches and pushes the contact. This occurs when the lever is in the "12 O'Clock" position and you must move it past this position to prevent the point motor "burning-out." ![]()
Our CDU module fits between the Power Supply and the switch or
switches to a SOLENOID POINT MOTOR. It is designed to deliver a short pulse of
energy to the solenoid to change the position of the point. A
Passing Switch will deliver a pulse of energy but if it gets stuck
in the mid-position, our CDU will prevent the point motor "burning
out."
CAPACITOR DISCHARGE UNIT MkII - MODIFICATION
Universal EU US Plug Switching Adapter AC 220V-240V To 5 V 12 V
24V Volt Power Supply DC 5V 12V 24V 1A 2A 3A 5A Power Adapter
Output Voltage 24v US Plug Current 1A $3.60 This gives you a 36v supply for less than $10.00 You just
need to wire the outputs in series.
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CHOICE
NUMBER 9:
The amount of energy delivered to the solenoid depends on the
voltage delivered to the module. For 12v DC supply, the solenoid
will work very delicately and will be suitable for small solenoids
used in "Z-scale." Supplying 16v AC will deliver FOUR times more
energy and will be suitable for larger scales and can operate 2
points. oooooooooooooo0000000000000000000000000000oooooooooooooooo CHOICE NUMBER 10: Talking Electronics has an In-line version that takes up
less space on your console.
This In-line CDU module has two LEDs that show the position of the point.
It is fitted to your control panel and the LEDs show the position of a point.
This very handy for a point that cannot be seen from the control area.
The input voltage needs to be 12v to 16v AC or DC and you may need two adaptors in series to get this voltage. See Chapter 1 for the Plug Packs (or Choice Number 11). oooooooooooooo0000000000000000000000000000oooooooooooooooo
CHOICE
NUMBER 11:
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A larger CDU is also available from
Talking Electronics, to change up to 8 points at the same time:
This Capacitor Discharge Unit is easy to
connect to your layout with screw terminals.
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CHOICE
NUMBER 13:
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NUMBER 14:
VOLTAGE REDUCER The VOLTAGE REDUCER MODULE consists of a 3-terminal block and 4
power diodes and screws into the 3-terminal block on the module.
If the input voltage is 17v, you can remove one of the diodes by soldering a link across one of the diodes (to short it out), as shown in the following image:
If the input voltage is 16v you can remove 2 diodes and if it is 15v, you do not need the VOLTAGE REDUCER MODULE. If you want to deliver 15.5v DC to CDU 18,000u Slimline - MkII with two plug packs, here is the circuit:
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The name: Capacitor Discharge Unit with SPDT Switch - SLIM
has been chosen to identify it from all the other CDU modules made
by Talking Electronics.
All the components fit on the PC board and the module comes with 2 x 1,000u electrolytics. The input can be 12vAC to 15vAC or 20vDC to 35vDC. You can make a 12v 24v or 36v supply very cheaply by using 24v and
12v plug packs. These are available on eBay for less than $10.00
(combined) including postage.
Now you can have 3 features in one module. The first feature is the power supply. This module connects to your track and you don't have to provide 15v AC or a higher voltage to charge the electrolytics. The module has an on-board charging and voltage generating section that accepts almost any voltage and charges the electrolytics to a maximum of 27v. The next feature is the variable voltage (or maximum voltage) for the electro's. You can reduce the voltage to as low as 13v for those solenoid points that do not need a large amount of energy for their activation. The third feature is the reed switch inputs. This allows the module to be used automatically to control a solenoid point so the point gets changed correctly when the train approaches from the other direction. And lastly, the kit comes with a TRACK-PICKOFF MkII connector that fits between the sleepers and connects to the rails with springy connectors. THE CIRCUIT |
SOLDERING THE KIT Soldering these kits is simple if you have a bit of experience in soldering small components because all the parts are identified on the PC Board. You will need tweezers for the surface-mount components. We supply solder THAT IS NOT CHINESE SOLDER. Do not use Chinese solder as it does not contain the correct percentage of tin and lead and it does not "run" or melt or flow properly and does not produce a shiny joint. It did not work for me and I threw it in the trash. The frustration of trying to get a shiny joint was enormous. The first things you add to the board are the 13 surface mount resistors. Add a small amount of solder to one land for each resistor and pick them up with tweezers with the numbers showing and solder one end with the solder that is already on the land. Then go around and solder the other ends by adding a small amount of solder to each resistor. Watch the solder "click" onto the resistor and it will look a little bit like a skateboard ramp. The rest of the components are through-hole and it does not matter if you start at one end of the board or with the small components first. Every component is identified on the board and most of the parts have to be fitted around the correct way - so look at the legend on the board. The LEDs must be soldered very quickly otherwise they will be damaged. The mark of a well-designed PCB is being able to put it together with a handful of parts and no other reference. And the mark of a well-designed circuit is 100% operation with every board. You cannot afford to be messing around, "adjusting" the component values and trying to work out why it does not work. That's why every value has a reason and a purpose. This can only be gained by working on hundreds of circuits and gaining the experience, knowledge and understanding. The circuits are provided with all the projects to give you this experience. And to help you fix something, if it "blows up." ![]()
Alternatively, you can ask for Track Pick-off "using Rail Joiners." You will need to get to the track, remove the rail joiners that presently connect the rails, and fit the track jointers as shown in the following image:
CONCLUSION oooooooooooo000000000000000000oooooooooooooo
CHOICE
NUMBER 17:
The original circuit used two 555 IC's. The new and
improved circuit uses a microcontroller and 15 fewer components !!
That's why some of the components are no longer required. |
The image on the left is just an example
to show the connection of the servo to the point. The servo
can lay down to take up less room.
There are many ways to
connect the servo to the "switching lever" and here's one
way that adjusts the movement of the arm on the servo to the
travel needed by the switching lever. The following images clearly
show how the 3.7g SERVO is connected to the point via a
LINKAGE:
THE SUPPLY
FITTING the REED
SWITCHES
PARTS LIST
CHOICE
NUMBER 20: KATO
Modules
are available for this project
from
The CIRCUIT
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WIRING A POINT MOTOR Point Motors take a high current when they are operated for the very short time they are intended to work. Most point Motors have a coil resistance of about 3.8 ohms and when operated on a supply of 12v, this will allow 3 amps to flow. Normally, wiring for 3 amp will require medium duty hook-up wire because the current will be flowing for a long period of time and thick wire prevents it getting hot. But with a solenoid-type Point Motor, it is only activated for less than a second. This means thin hook-up wire is perfectly suitable. 3 metres of thin hook-up wire will have a resistance of about 1 ohm and if 3 amps flows, the voltage drop across the wire will be 3 volts. But most Capacitor Discharge Units are charged to a voltage higher than 12v and can be 24v. If we take 24v, the current will be 5 amps and the voltage drop will be 5v. This gives the solenoid 19v. The Capacitor Discharge Unit is designed to give 24v at the beginning of the pulse and gradually drop to almost zero after less than 1 second. This give the solenoid Point Motor an initial kick to start moving and then the current gradually reduces so the "end clunk" is not so strong. This means the wiring to the Point Motor can be almost any thickness as it has very little effect on the operation of the solenoid. |
Talking Electronics has produced a number of different TRAIN THROTTLES.
Most locos take about 300mA to 500mA and need a voltage of about 12v for full
speed.
There are two types of TRAIN THROTTLE: ![]() Two Amp Power Supply circuit diagram. It is also called 2-amp THROTTLE ![]() The completed project, showing the placement of the parts The input voltage can be AC or DC. The DC voltage needs to be at least 16v6 to get 12v DC out. If you supply 17v to 20v DC, nothing will be damaged. Just the 470R resistor will get slightly hotter when the input voltage is above 18v. The 2-Amp POWER SUPPLY project is
HERE You will need a double-pole double-throw toggle switch to reverse the train. Ask for it. $2.50 extra.
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TRAIN THROTTLE No2.
(kit: $18.00 with leads)
Click Here
to order.
The $2.50 plug Pack above was purchased as 12v @ 1 amp. It was
easily opened-up via a screw and clip, to reveal the PC board shown
below.
oooooooooooooo0000000000000000000000000000oooooooooooooooo THROTTLE WITH PWM Kit: $28.50 plus $6.50 postage.Click HERE to buy a kit. Built and Tested: $35.00 plus $6.50 postage. Click HERE to buy a module. This is our latest design with forward and reverse via the yellow CONTROL POT. This project does not need a reversing switch as the pot provides zero speed when at 12 O'clock and reverse when turned to the left and forward when turned to the right. The output is Pulse Width Modulated (PWM) to give the loco smooth starting. By this we mean the motor gets pulses from the throttle that allow it to start very slowly. The module is capable of delivering 3 amps (due to the thickness of the tracks) and the power diodes are 5 amp. Additional heatsink fins will be needed for currents above 2 amp. But we suggest a 1-amp supply for most loco's. The 4 FETs on the output bridge are capable of handing more than 10 amp and the trackwork on the board can be modified to handle 5 amps by soldering tinned copper wire along the tracks identified with additional solder pads. This means the controller can be used for garden layouts where the loco will draw 5 amps. If you want to control more than 5 amps, you will need to connect the supply directly to the MOSFETs in the bridge and by-pass the 5 amp diodes. The switch at the right is the on-off switch. The two LEDs on the board indicate forward and reverse, in case you cannot see the loco on a large layout.
All the digital signals are controlled (and generated) by the microcontroller and
the pot determines the timing of the waveform and the
activation of the H-bridge.
You can request the following type if you do not want to use the rail joiners:
The following images of controller are called DC CONTROLLERS. They increase and decrease the DC voltage and most have a reversing switch. There is nothing wrong with these controllers, but if you want to start the train very slowly, and have a controller-knob that has both forward and reverse, THROTTLE WITH PWM is the upgrade. If you have one of the controllers shown below or a similar type that has a 0-100 scale AND a reversing switch, you can connect its output to the input of THROTTLE WITH PWM and get the new features. HERE'S WHAT TO DO Connect your throttle to the mains and turn the knob or lever to maximum. Measure the voltage coming out of the throttle and make sure you identify the positive lead. Now turn it off and connect the positive lead to the "+" DC screw terminal on THROTTLE WITH PWM module. Now connect the other lead to the "-" DC terminal on THROTTLE WITH PWM module. Put your throttle under your layout, making sure you do not touch the handle or the reversing switch. Now connect your track to the two screw terminals marked "to track" on the THROTTLE WITH PWM module. The THROTTLE WITH PWM module will use your throttle as a power supply and deliver PWM to your layout via the forward/reverse knob on THROTTLE WITH PWM.
Some of the following controllers deliver just 7v and some are up to 16v AC output and/or 16v DC output. They all have forward/reverse on the control handle so the only improvement you will get by connecting to the THROTTLE WITH PWM module above is PWM.
The Transformer |
The output of the
servo moves about 70 degrees as this will give the greatest "throw."
You can select the hole on the arm to produce the travel you want.
Here is a set of gates controlled by 4 servos.
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Theory, Test Gear
& More Projects
MATRIX BOARDS Talking Electronics has produced a lot of matrix board in all sorts of sizes and shapes so the board is ready and neat for the layout of components. These boards cost just $2.00 for the small boards, $2.50 for the medium size and $3.00 for the larger boards. Simply email Colin with the number and size and they can be sent to you. Click Here to order
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THEORY
THE MULTIMETER I test all my projects with a $5.00 multimeter !! WHY??? Because an analogue multimeter puts a load on a circuit and the reading MUST be genuine. Secondly, an analogue multimeter will show fluctuations in a circuit and show when a certain part of a circuit is not maintaining stability. And thirdly, an analogue multimeter will respond to changes and pulses much faster than a digital meter. Lastly, if I can design and test a circuit with a cheap meter, everyone else should be able to do the same when using a more-expensive meter. Finally, an analogue meter lasts a lifetime. And if you damage it, the cost is only $5.00 And you get 500mA range, a digital meter gives 200mA. Analogue Meters are on eBay I have digital meter when I want to read voltages accurately.
Current flows through the multimeter from the
positive probe to the negative probe and the arrow on top of the meter
above shows this direction.
If you cannot remember how to connect a multimeter
when testing CURRENT, tilt it slightly so the positive terminal is
higher than the negative terminal and lay the red probe on the bench,
HIGHER than the black probe. |
THEORY
SERVOS
![]() The servo has a "pot" as the feedback but it does not have any "stops" and thus the wiper passes the end of the curved track. I tested this servo by trying to find the "dead spot" where the servo did not respond to a position that would normally be past either of the "end-stops." The program in the servo detects when the wiper is not on the track and sends the arm to a starting position - proving this servo is the best one to buy. "No stops" means the servo will not get jammed if it is forced (by an outside force). Sometimes, when these servos are used in a Robot-Fighting situation, they get forced to move (when in a collision) and this jams the gears. This servo does not have that fault. This servo also operates slowly (when connected to some of our modules) and does not "jitter" when used in our projects. |
THEORY
The
reed switch only detects a magnet when the magnet is in
positions A and
C. This
is because the magnetic flux produced by the magnet "hits"
the left or right reed and magnetises it in a process called
TEMPORARY MAGNETISM or INFLUENCED MAGNETISM and since the
other reed is not magnetised, the two reeds "stick
together." When the magnet is in the centre of the reed,
both reeds get magnetised by the North pole of the magnet
and they do not make contact. |
THEORY
This is just one way to connect it to a circuit when you want to be able to connect a Hall Device or a reed switch to the same input terminals of a project.
The Hall device is being
used in an unusual way in this project, with the output connected to
the "supply lead." |
TEST EQUIPMENT
LED TESTER This project tests LEDs and tests for continuity and tests for other things as well. It's a very handy piece of test gear. See the full project HERE
|
PROJECT TRACK PICK-OFF Track Pick-offs are available from Talking Electronics for $2.00 plus postage. This Printed Circuit board is fitted between the sleepers and has contacts to touch the rails so the voltage on the track can be monitored or delivered to a project. If the current taken from the track is very small, it will not interfere with the operation of the train(s) on the layout and is called LEACHING. A little bit of power is taken from the track and this saves running wires all the way back to your control panel. Talking Electronics has designed 2 of these TRACK PICK-OFF boards: Track Pick-Off MkI has two track joiners soldered to the board and this is fitted between two sections of your layout. The images below show this board and how it it fitted to the track:
Here is the module connected to a project:
If it is not easy to connect the track joiners to
your layout, we have:
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TEST EQUIPMENT TRACK TESTER This project tests the voltage on your track. It's another very handy piece of test gear. See the full project HERE The Track Tester kit costs $10.00 AUD plus $4.50 AUD postage. The Track Tester is also available ready-made for $16.50 USD (posted) It alerts you to the presence of DCC via the piezo diaphragm and the voltage of your track at all parts of the layout. Click Here to buy a Track Tester.
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TEST EQUIPMENT
OVER-CURRENT DETECTION Requested by William Hicks: This circuit detects when the tracks are overloaded by too many trains. ![]() Note: Each 1R resistor needs to be 0.5watt 0R22 needs to be 5watt!! The circuit will drop 1.4v when full detection-current is flowing. Here is the simplest over-current circuit:
Kits
are available for this
project from |
FLASHING RAILROAD
LIGHTS This circuit flashes two red LEDs for a model railway crossing. ![]() ![]() |
FLASHING LIGHTS FOR MODEL
RAILWAY CROSSING: A flashing LED is used to create the timing for the flash-rate and the transistor provides the alternate flash for the second set of LEDs. The first circuit comes off the web, but Colin Mitchell doesn't think it will work. See his circuit below. ![]() The top two 1k resistors are current-limiting resistors and can be increased if you want the LEDs to be dull. The 2k2 makes sure the two LEDs are completely turned-off because the flashing LED draws a small current when it is off and this shows in the two LEDs. The lower 1k may need to be reduced to 470R to completely turn the transistor OFF. The other circuit does not have any of these features. The flashing LED has to be an ON-OFF flashing red OR green LED. Not a red-green flashing LED or a RED-GREEN-BLUE flashing LED. The flashing LED actually has an in-built resistor and will work on 2v to 5v. But we are using its feature of "taking a small current" when illuminated and then "taking almost zero current" when not illuminated, to "switch the transistor." You can get the CROSSING LIGHTS plastic mouldings from Talking Electronics. They will take 3mm LEDs. Cost: $6.00 for 2 Crossing Lights with 4 LEDs and 2 metres of fine 0.25mm enamelled wire. . You need to "push-out" the red lens and fit the 4 x 3mm red LEDs and carefully solder wires to the LEDs.
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TRAFFIC LIGHTS Here's a clever circuit using two 555's to produce a set of traffic lights for a model layout. The animation shows the lighting sequence and this follows the Australian-standard. The red LED has an equal on-off period and when it is off, the first 555 delivers power to the second 555. This illuminates the Green LED and then the second 555 changes state to turn off the Green LED and turn on the Orange LED for a short period of time before the first 555 changes state to turn off the second 555 and turn on the red LED. A supply voltage of 9v to 12v is needed because the second 555 receives a supply of about 2v less than rail. This circuit also shows how to connect LEDs high and low to a 555 and also turn off the 555 by controlling the supply to pin 8. Connecting the LEDs high and low to pin 3 will not work and since pin 7 is in phase with pin 3, it can be used to advantage in this design.
Both 555's are wired as oscillators in astable mode and will oscillate ALL THE TIME when they are turned ON. But the second 555 is not turned on all the time! The first 555 turns on and the 100u is not charged. This makes output pin 3 HIGH and the red LED is not illuminated. However the output feeds the second 555 and it turns on. Output pin 3 of the second 555 turns on the green LED and the second 100u charges to 2/3 rail voltage and causes the 555 to change states. The green LED goes off and the orange LED turns on. The second 100u starts to discharge, but the first 100u is charging via a 100k and after the orange LED has been on for a short period of time, the first 555 changes state and pin 3 goes LOW. This turns on the red LED and turns off the second 555. The first 100u starts to discharge via the 100k and eventually it changes state to start the cycle again. The secret of the timing is the long cycle-time of the first 555 due to the 100k and the short cycle due to the 47k on the second 555. |
4 WAY TRAFFIC LIGHTS
This circuit produces traffic lights for a "4-way" intersection. The seemingly complex wiring to illuminate the lights is shown to be very simple. This circuit is used in the next article. ![]() |
4-Way
Traffic Lights Kits
are available for this
project from
This wiring diagram shows how the LEDs are connected in the over-head light. All the anodes are connected to the black wire and the cathodes emerge as Green, Orange and Red. The 4-screw terminal block is looking at the where the wires enter the terminals and this is clearly shown in the photograph above. |
This project operates crossing
lights automatically when the train enters the crossing and turns them
off automatically. The flash-rate can be adjusted as well as the
brightness of the lights and the overall length of time for the
flashing. No other module on the web offers these features.
Two LEDs on the module indicate when the lights are flashing and the module comes with 4 extra LEDs for those who have bought crossing signals without the LEDs installed.
The circuit has a number of very clever features. .
It uses two 555 ICs to provide all the functions. The
signal diode on the first 100u discharges the 100u quickly when the
circuit turns off so the timing can restart again with full duration.
The module is available fully-built and only needs to be connected to
12v DC. Connect the reed switches or Hall devices to the input terminals
and switched ON.
TWO versions of this project are now available because some 2-aspect lights have a black wire that goes to the anode of each LED via a resistor and some are wired with the black lead to the cathode of the two LEDs. The difference between the two PC boards can be clearly seen by the white frame around the output pins.
A new version of JIM'S CROSSING LIGHTS (called ver5) has been produced for customers who cannot work out which type of lights they have installed. It has a change-over switch and works with both types - very clever !!! ![]() The image above shows the fully built and tested module. It comes with 2 reed switches on 1200mm leads and 2 super magnets for $25.00 usd plus $6.50 usd postage. Order a module: Jim's Crossing Lights for TypeA&B lights ![]()
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