Model Railroad & Misc. Electronics

Power Supplies And Safety

555 and 556 Timers                Voltage Comparators

Circuit Commons


Recent Additions and Revisions List (25 March, 2014)

List Of Sections On This Page

| Current Activated Train Detectors | Light Activated Train Detectors | Railroad Signals Circuits |
| DCC Circuits | DC Throttles | Switch Machine Controls | Automatic Reversing Circuits |
| Automatic Control Circuits | Pageless Circuits | Miscellaneous Items | Science |
| Basic Electronics | Parts List | OpAmps | Photographs | Caveat |
| | Turbine | |

List Of Circuit Boards Available Through This Site

Full Circuit List


email - rpaisley4@cogeco.ca


About This Web Site

  Welcome to a page of electronic circuits that are mostly for model railroads. Shown are circuits that were developed to solve certain problems or achieve a desired control function. There are throttle, train detection, animation, control and general purpose circuits on this page.

  Following this section is a list of the circuits that appear on these pages. Select one of the internal page links or scroll down the page until you find something of interest.

  The link under the paragraphs in each section will take you to the document from which the text is taken. These documents will provide more detailed explanations and schematics for the circuits.

  The circuits listed in the index sections appear in no particular order but have been loosely grouped by the type of function they perform. The Numbers to the left of the index listings are arbitrary. There is also a "Miscellaneous Items Index" that features circuits that may not be model railroad related and non electronics related pages.


About The Circuits On This Site

  The circuits on this site are purposely designed to be as simple and efficient as possible. In most cases they perform only one function but do it well.

  The circuits use basic electronics that the average person can find parts for and build on their own. Computers and microcontrollers have largely been avoided.

  Some circuits and pages don't have a particular use but are meant only to be educational or informative.

  Some of the circuits are of general interest, generally mine, and may be of little use. They are functional however and at the very least, a useful waste of my time.

  A few of the circuits on this site, in their original form, are or were in use by the London Model Railroad Group. This large, 'O' Scale club layout is located at 69 Holbourne Ave., London, Ontario, Canada. Public viewing nights are the first Tuesday of the month from October to May.


Caveat Lector

  I am not an electronics professional, although I play one on the web, and only design these circuits as a hobby.

  Therefore I can make no claims to the quality or usefulness of the circuits shown on this page. They should however work as stated and will not be dangerous to persons or property when used in their intended manner.

  If you see any problems with the circuits or have any suggestions please let me know.

  If you have questions, comments or need some help regarding the circuits on these pages you may contact me via email at: Rob Paisley. (rpaisley4@cogeco.ca)

Rob Paisley



  If this is your first visit to this site, please read the sections above for general information about the site. Thank you.

  Pages in English and French are denoted by the addition of (E+F) at the end of their links.

Main Circuit Index

These pages are best viewed with the browser of your choice and an open mind.

Light Activated Detector Circuits

  1. 8 Photo-Detector Circuit - Inverting (PCB)

  2. 8 Photo-Detector Circuit - Non Inverting (PCB)

  3. 4 Photo-Detector Circuit - Delayed Release (PCB)

  4. Photo Detector Circuits (E+F)

  5. Photo-Detector Circuit (LM324 / LM556)

  6. Above And Across The Track Infrared Detectors

  7. Day and Night Infrared Detection

  8. Laser Pointer Train Detector

  9. Block Occupancy Detector Helper

  10. Light Detector Circuit (LM393/LM555)

  11. 4 & 8 Infrared - Proximity Detectors (TSOP4830)

Current Activated Block Occupancy Detector Circuits

  1. Dual - Transformer Type Block Occupancy Detector - VT-5 (PCB)

  2. Transformer Type - DCC Block Occupancy Detectors

  3. Diode Drop - DCC Or AC Block Occupancy Detectors - Comparator Outputs

  4. Optoisolator Block Occupancy Detector

Switch Machine Control Circuits

  1. Reversing Loop Switch Machine Controller (PCB)    (Tortoise® Type Machines)

  2. 556 Timer Stall-Motor Switch Machine Drivers (PCB)    (Tortoise® Type Machines)

  3. Capacitor Discharge - Switch Machine Power Supplies (E+F)

  4. Toggle Switch Control Of Twin Coil Switch Machines

  5. Toggle Switch Control Of Single Coil Switch Machines    (KATO® Machines)

  6. Twin Coil Switch Machine - Automatic Reversing Loop Circuits

  7. Diode Matrix Systems For Stall-Motor Switch Machines

  8. Route Control For Stall-Motor Switch Machines

  9. Stall-Motor Switch Machine Power Supplies

  10. 324 OpAmp Stall-Motor Switch Machine Drivers

  11. Turnout Anti-Derail Protection

  12. High Current Switch Machine Motor Driver    (Fulgurex® Machines)

  Note: The terms NORMAL and REVERSE for turnout alignment on the pages listed in this section are arbitrary and will depend on the actual needs of the user of the circuits.


Automatic Reversing Circuits

  1. Automatic Reversing Circuit - Mk VII (PCB)

  2. Automatic Reversing Circuit - Inexpensive System (2002)

  3. Automatic Reversing Circuit - Mk IV (2000)

Automatic Operations Circuits

  1. Rail Crossing Diamond Protection - Hybrid

  2. Rail Crossing Diamond Protection - Specific

  3. Automatic Station Stop Circuit

  4. Automatic Incline Railway System

  5. 5 Times Around Circuit for Layout Animation

  6. Audible Train Approach Warning

Signals Circuits

  1. 2011 - Grade Crossing Signals And Gates Circuit (PCB)

  2. Grade Crossing Bell Ringer Circuit (PCB)

  3. Special Grade Crossing Circuits

  4. 3 Light - Model Railroad Block Signals Circuit (PCB)

  5. 556 Search Light Model Railroad Signals (PCB)

  6. Traffic Light Control Circuit (20 Output Sequencing Circuit) (PCB)

  7. 2012 - Single Traffic Light Driver Circuit (PCB)

  8. Basic Grade Crossing Flasher Circuits (LM556) (E+F)

  9. Grade Crossing Bell Ringer (Original)

  10. 6 Aspect - Searchlight Signal Driver (LM555)

  11. Miscellaneous Signals

Various DC Throttles

  1. Joy Stick Controlled - Modernized Toy Throttle

  2. Various Transistor Throttle Circuits

  3. A 3 Amp, Three Terminal Regulator Type Throttle (E+F)

  4. Silicon Controlled Rectifier Type Throttles

DCC Circuits And Related Pages

  1. 3 Amp - DCC Track Booster - 2011 (LMD18200) (PCB)

  2. 1 Amp - DCC Accessory Booster (SN754410) (PCB)

  3. DCC Ammeter (ZXCT1009) (PCB)

  4. Diagrams And Schematics For My MiniDCC© System

  5. Files For The Original MiniDCC© System

  6. Waveforms, Currents and Voltages For DCC Systems

  7. Flashing Rear-End Device For DCC Systems

  8. DCC Boosters and 'H' Bridge Motor Control Circuits

Miscellaneous Circuits and Information Pages

  1. UNIPOLAR Stepper Motor Driver (2012) (PCB)

  2. BIPOLAR Stepper Motor Driver (2012) (PCB)

  3. Electromechanical Circuit Breaker For Larger Scales (PCB)

  4. EDE1200 - UNIPOLAR Stepper Motor Driver (PCB)

  5. Retrofitting Garden Lights With LEDs Using License Plate Lights

  6. Cam Action - Swing Gate Illustration

  7. LED - Current Limiting Resistor Calculator

  8. LM555 Timers - Circuits and Calculators

  9. Voltage Comparator Circuits (LM339 / LM393)

  10. Fast Acting Electronic Circuit Breakers

  11. Using "AT" Computer Power Supplies

  12. Push-In Terminals for 0.042" Dia. Holes

  13. LEGO® RCX Brick Voltage Recorder

  14. LEGO® RCX Brick Rechargeable Battery Tester

  15. Replacement For The LM3909 LED Flasher / Oscillator

  16. Basic Electronics For Model Railroads

  17. Transformer Selection Guide Sheet

  18. An Ammeter Made From A Voltmeter

  19. Solid State Relays (E+F)

  20. Model Railroad Odometer Car (1994 M.R. Magazine article)

  21. Hendeca (11 Step) Resistance Substitution Box

  22. Integrated Circuit Pinout Diagrams

  23. Circuits Without Pages Of Their Own (The "x" Files)

  24. Regulated Power Supply Circuits

  25. "H" Bridge Direct Current Motor Control Circuit (LM311)

  26. Wire Coat Hanger Cable Guides (E+F)

  27. UNIPOLAR Stepper Motor Driver (2008)

  28. BIPOLAR Stepper Motor Driver (2008)

Pictures

  1. Canadian National Railways - St. Clair River Tunnel Construction Photos


Making Contact

Send email to the author of this page at - rpaisley4@cogeco.ca (Rob).

Circuits and Features List


Cam Action - Swing Gate Illustration

  This diagram illustrates the principle effect of rotating an arc excentrically away from a similar arc. The net result is an increasing gap between the circumfrences of the two arcs.

Cam Action - Swing Gate Illustration

Retrofitting Garden Lights With LEDs Using License Plate Lights

  The object of this project was to replace the 11 watt, low voltage, incandescent lamps used in these outdoor lighting fixtures, 8 fixtures in total, with LEDs. The lamps normally used in these fixtures either burned out or often would became loose and would go out.

Garden Lights With LEDs

UNIPOLAR Stepper Motor Driver (2012) (PCB)

  This page features simple and inexpensive, stand alone UNIPOLAR stepper motor driver using parts that are available from many sources.

  The driver is designed for medium and low speed applications with motors that draw up to 1.0 amp per phase. Higher current motors can be driven by adding external transistors.

Unipolar Driver

BIPOLAR Stepper Motor Driver (2012) (PCB)

  This page features simple and inexpensive, stand alone BIPOLAR stepper motor driver using parts that are available from many sources.

  The driver is designed for medium and low speed applications with motors that draw up to 1.0 amp per phase. Higher current motors can be driven by adding external transistors.

Bipolar Stepper

3 Light Model Railroad Block Signals Circuit (PCB)

  This a 3 Light type model railroad block signal circuit that can produce solid - Red, Yellow and Green signal aspects. The signals can be connected for NORMAL or APPROACH type lighting for the Green signal.

  The basic circuit can also be used for 2 Light signals, PRR - position light type signals and can be adapted for search light type signals that use bicolour LEDs.

Block Signals Circuit

Reversing Loop Switch Machine Controller (PCB)

  This circuit is for a switch machine controller for reversing loops. The circuit is light activated and designed to automatically operate stall type switch mahines.

Switch Machine Controller

2012 - Single Traffic Light Driver Circuit (PCB)

  The circuit on this page is designed to control a Single - Three Light (Green - Yellow - Red) traffic light assembly. The the length of time that each light is lit is independently adjustable between 4 and 40 seconds for the parts values specified.

Traffic Light Driver

2011 - Grade Crossing Signals And Gates Circuit (PCB)

  This circuit automatically controls crossing signals and gates in a prototypical manner.

  The circuit uses a bidirectional time delay that staggers the gates and lights so that they operate as would be seen at a typical crossing.

2011 - Grade Crossing Circuit

3 Amp - DCC Track Booster - 2011 (LMD18200) (PCB)

  The DCC booster shown on this page uses the LMD18200 motor driver H-bridge IC. The booster's designed output rating is 3 amps at 15 volts.

DCC Track Booster

1 Amp - DCC Accessory Booster (SN754410) (PCB)

  This booster is designed to power stationary DCC decoders used to control off-track accessories, switch machines and signals.

DCC Accessory Booster

Photo-Detector With Delayed Release And Bipolar Output

- The LEDs Can Be ON or OFF When The Phototransistors Are Dark -

  The circuit on this page is for a visible and infrared light detector circuit board. The input is sensed by a LM324 operational amplifier and the outputs is from a LM555 timers.

Photo-Detector Circuit

8 Photo-Detector Circuit - Inverting (PCB)

- The Output LEDs Are ON When The Phototransistors Are Dark -

  The circuit on this page is for a visible and infrared light detector circuit board that has 8 detectors. LM339 voltage comparators are the active element.

Inverting Photodetector

8 Photo-Detector Circuit - Non Inverting (PCB)

- The Output LEDs Are OFF When The Phototransistors Are Dark -

  The circuit on this page is for a visible and infrared light detector circuit board that has 8 detectors. LM339 voltage comparators are the active element.

Non Inverting Photodetector

Grade Crossing Bell Ringer Circuit (PCB)

  This circuit is a driver for a mechanical - Grade Crossing Bell Ringer - that was originally built for the London Model Railroad Group.

Bell Ringer

Electromechanical Circuit Breaker (2010) (PCB)

Fast Acting

  The circuit on this page is for a fast acting electronic circuit breaker for use with fixed and variable, low voltage AC and DC systems such as model railroad throttles. The circuit breaker's trip current setting has an adjustable range of 0.5 to 10 amps.

Circuit Breaker

UNIPOLAR Stepper Motor Driver (EDE1200) (PCB)

  This page features a Unipolar Stepper Motor driver that uses an EDE1200 (Unipolar) Stepper Motor Controller IC produced by eLab Digital Engineering to provide 5 control functions, including half-stepping.

Stepper Driver

4 Photo-Detector With Delayed Release And Bipolar Output (PCB)

- The LEDs Can Be ON or OFF When The Phototransistors Are Dark -

  The circuit on this page is for a visible and infrared light detector circuit board that has 4 detectors. The inputs are controlled by an LM339 voltage comparators and the outputs are from LM556 timers.

  The outputs have settable delayed release and can source or sink up to 200 milliamps. The output's release delay can be controlled by selecting the desired values for the resistors and capacitors at the input terminals of the LM556 timers.

4 Photo-Detector Circuit

3 Amp DCC - Track Booster - 2009

  The DCC booster shown on this page uses the LMD18200 motor driver H-bridge IC. The booster's designed output rating is 3 amps at 15 volts.

Track Booster

Transformer Type Block Occupancy Detectors

  In these circuits a transformer is used to isolate the detector circuitry from the track power circuit.

Occupancy Detector

Quadruple And Octuple Infrared - Proximity Detectors (TSOP4840) (PCB)

  The circuits on this page are for an Infrared - Proximity Detector using the Vishay Electronics - TSOP4830 "IR Receiver Modules for Remote Control Systems".

IR Proximity Detector

DCC Ammeter (ZXCT1009) (PCB)

  The circuit shown on this page allows inexpensive digital multimeters to measure currents in DCC systems. The 2010 circuit is designed to use a 20 milliamp DC milliammeter to monitor the current but other types of meters could also be used with this circuit.

DCC Ammeter

Traffic Light Control Circuit (20 Output Sequencing Circuit) (PCB)

  This page features a circuit that has twenty open collector outputs that turn on one at a time in a continuous sequential manner. The circuit make use of the 74LSxx family of TTL integrated logic devices. The circuits are designed to drive light emitting diodes or low current, low voltage incandescent lights but can also drive other loads of up to 80 milliamps.

Sequencing Circuit

Fast Acting Electronic Circuit Breakers

  The circuit breakers on this page make use of the Zetex - ZXCT-1009 "High Side Current Monitor' integrated circuit. The circuits have variable trip current settings and are designed for low current applications.

  Two circuit breaker designs are shown; The first has its power isolation device on the Low or common side of the circuit while the second has it isolation device on the High or supply side of the circuit. Both designs use MOSFET isolation devices.

Electronic Circuit Breakers

OpAmp Stall-Motor Switch Machine Drivers

  The circuits on this page are switch machine drivers that can be used to operate Stall-Motor type switch machine motors. The circuits use LM324 Quad or 358 Dual operational Amplifier chips to provide a PUSH-PULL output to reverse the polarity of the supply to the switch machine motors.

Switch Machine Drivers

Using "AT" Type Computer Power Supplies

  "AT" type computer power supplies are often used by model railroaders to provide accessory power for their layouts. These supplies are reasonably inexpensive due to their age and have been removed from old personal computers.

AT Power Supplies

Transformer Type Block Occupancy Detector - VT-5 (PCB)

  This block occupancy detection circuit uses a current sense transformer to isolate the detector circuit from the track power circuit. The output section of the circuit takes its power from an external power supply and uses a LM555 timer to provide the release time delay and both an Open Collector and Bipolar output each detector.

Block Occupancy Detector

Comparator Based - Diode Drop - Block Occupancy Detectors For DCC Or AC

  Two block occupancy detectors using diodes and voltage comparators.

Block Occupancy Detector

General Purpose Block Occupancy Detector

  This page presents block occupancy detector designed for general purpose use on systems where the polarity of the power to the track is reversible.

General Purpose Block Occupancy Detector information

Optoisolator Block Occupancy Detector

  This page is about a block occupancy detector that uses an optoisolator to electrically separate the track from the detector output. Four variations of the detector are shown.

Optoisolator Block Occupancy Detector information

Miscellaneous Signals

  Some simple signals circuits that do not have pages of their own.

Miscellaneous Signals

Push-In Terminals for 0.042" Dia. Holes

  This page shows a less expensive alternative to screw type terminal blocks for use on printed circuit boards. These are described as "Push-In Terminals for 0.042" Dia. Holes" and require soldering of external connections.

Push-In Terminals

LEGO® RCX Brick Voltage Recorder

  The images shown on this page show circuits that can used to measure and record with a LEGO® RCX Brick that comes with the LEGO® MINDSTORMS and LEGO® ROBOLAB robotics sets

Voltage Recorder

LEGO® RCX Brick Rechargeable Battery Tester

  The circuit on this page is for a rechargeable battery tester using a LEGO® RCX Brick to gather voltage verses time data and then upload the data to a PC using the ROBOLAB Software.

Battery Tester

Replacement For The LM3909 LED Flasher / Oscillator

  This page features a replacement circuit for the LM3909 LED Flasher / Oscillator. The replacement circuit uses discrete components and is essentially the same as the internal circuit of the LM3909.

LM3909 Replacement

Hendeca (11 Step) Resistance Substitution Box

  This is an inexpensive way to make a stepped resistance box using a Single Pole - Twelve Position rotary switch and eleven resistors for each switch.

Substitution Box

Basic Electronics For Model Railroads

  This pages in this section of the site will present basic information about electronics for Model Railroaders. Pages will be posted with information on various components and simple circuits that a model railroaders are likely to use in their hobby.

Basic Electronics

Toggle Switch Control Of Twin Coil Switch Machines

  These circuits allow an ON-ON type DPDT toggle switch to control a twin coil switch machine motor. The handle of switch can then be used to indicate the route selected. The circuits are also able to control LEDs that could be used to indicate the selected route.

Toggle Switch Control

Toggle Switch Control Of Single Coil Switch Machines

  This circuit allow an ON-ON type DPDT toggle switch to control a single coil switch machine motor such as those made by Kato®. The handle of switch can then be used to indicate the route selected. The circuit is also able to control LEDs that could be used to indicate the selected route.

Toggle Switch Control

Flashing Rear-End Device For DCC Systems

  This circuit is for a "F.R.E.D." that is designed to be used with DCC control systems. The circuit is based on the LM555 timer chip.

Flashing Rear-End Device

6 Aspect - Searchlight Signal Driver (LM555)

  The circuit on this page is a 6 Aspect driver for a bicolour LED type Searchlight Signal. The available signal indications are; SOLID - RED, YELLOW, GREEN, and FLASHING - RED, YELLOW and GREEN. The circuit can also turn the signal OFF for approach lighting if desired.

6 Aspect - Searchlight Signals

Waveforms, Currents and Voltages For DCC Systems

  This page attempts to show the voltage waveforms associated with model railroad DCC systems as they would be seen with an oscilloscope. Also methods of measuring DCC system voltages and currents are shown.

DCC Waveforms and Voltage

Diagrams And Schematics For My MiniDCC© System

  This page shows schematics and diagrams for a MiniDCC© system that was built for my personal use.

My MiniDCC© System

Files For The Original MiniDCC© System

  This page features schematics and diagrams that are for use with the MiniDCC© system. - A DCC ( Digital Command Control) do-it-yourself project....

MiniDCC© System

'H' Bridge Direct Current Motor Control Circuits and DCC boosters

  This page features H-Bridge circuits used for controlling direct current motors. Several designs are shown using both CMOS and bipolar power devices.

H-Bridge

Joy Stick Controlled - Modernized "Toy" Throttle

  This page presents a new version of the - 'Modernized "Toy" Throttle' circuit that is shown on the 'Various Transistor Throttles' page at this site.

  This version was specifically design to be used by a handicapped person and is controlled by a single axis joy stick that operates microswitches at each end of its arc of travel.

Joy Stick Controlled Throttle

556 Search Light Model Railroad Signals (PCB)

  This circuit controls a Search Light type signal head and produces solid - RED, YELLOW or GREEN indications.

Search Light Signal

Block Occupancy Detector Helper

  This circuit would be used to hold a BLOCK OCCUPIED condition as a train passes out of the block even if the normal detector is not sensing a train.

Block Occupancy Detector Helper Circuit

Light Emitting Diode - Current Limiting Resistor Calculator

  The calculators on this page can be used to find current limiting resistors and currents for Light Emitting Diodes.

  The first calculator determines the resistance for a desired LED current while the second calculates the current for a given resistance.

Current Limiting Resistor Calculator

Stall-Motor Switch Machine Circuits

  Some power supply and control options for Stall-Motor switch machines

Stall Motor Switch Machine Circuits

Route Control For Stall-Motor Switch Machines

  This page shows some methods of track routing control for Stall-Motor type switch machines. The principle method uses a 2 Pole - Multi Position rotary switch while an alternate uses optoisolators and transistors to select the routes.

Route Control

Canadian National Railways - St. Clair River Tunnel Construction Photos

  Some pictures of the tunnel boring machine used to dig the second railway tunnel under the St. Clair river and between Sarnia, Ontario and Port Huron, Michigan.

Canadian National Railways - St. Clair River Tunnel Construction Photos

LM555 Timers - Circuits and Calculators

  This page presents general information and tips for the LM555 timer. If you would like to try any of these ideas please take time to do some experimenting before using them in an actual circuit. All of the solutions on this page can be applied to the LM556 Dual timer chip as well.

  Also on this page are calculators that will give the output times of LM555 timers for a given set of component values.

LM555 Timer

Automatic Reversing Circuits - Inexpensive System

  This page presents a low tech, low cost and reasonably simple automatic reversing circuits. They uses toy train set power packs to control the top speed of the shuttle while diodes in the track circuit provide a method of stopping the shuttle at the ends of the track as well as crude control of the trains acceleration and deceleration.

Automatic Reversing Circuits - Inexpensive

Automatic Reversing Circuit - Mk IV

  This page is for an automatic direction reversing circuit that will control the point to point operation of a "shuttle" such as an RDC car or a short train. The shuttle will travel from one end of the track to the other wait for a preset time and then return to its start point, wait and then repeat the cycle.

Automatic Reversing Circuit - Mk IV

Automatic Reversing Circuit - Mk VII

  This page is for an automatic direction reversing circuit that will control the point to point operation of a "shuttle" such as an RDC car or a short train. The shuttle will travel from one end of the track to the other wait for a preset time and then return to its start point, wait and then repeat the cycle.

  The circuit is also capable of being controlled by one or more automatic station stops as the SHUTTLE travels along the track.

Automatic Reversing Circuit - Mk VII

Diode Matrix Systems For Stall-Motor Switch Machines

  The circuits on this page are basic designs for "Diode Matrix" switch machine control systems that can be used to operate "Stall-Motor" switch machines in 'Ladder' type storage yards or other multiple turnout areas.

  The driver circuits themselves use LM556 dual timer chips to reverse the polarity of the voltage to the switch machine motors.

Matrix Systems For Stall-Motor Switch Machines

Stall-Motor - Switch Machine Drivers (LM556) (PCB)

  The circuits on this page are switch machine drivers that can be used to operate Stall-Motor type switch machine motors. The circuits use LM556 dual timer chips to provide a PUSH-PULL output to reverse the polarity of the supply to the switch machine motors.

556 Switch Machine Driver

Laser Pointer Train Detector

This train detector makes use of hand held laser pointer devices that are widely available to detect trains over long distances.

Laser Pointer Train Detector

Twin Coil - Automatic Reversing Loop Circuits

  This page is about automatic reversing loop control circuits. The first switch machine controller is very basic. More complicated circuits will be added as they can be thought up and tested out.

Automatic Reversing Loop

Automatic Station Stop Circuit

  The "Automatic Station Stop Circuit" brings a train to a station stop in two braking steps and then sends the train on its way after a set period of time.

  The first braking step slows the train gradually until it is at the station. The second brake step then stops the train just quickly enough to allow the first or second coach to stop in front of the station.

Automatic Station Stop Circuit

UNIPOLAR Stepper Motor Driver - 2008 (74194)

  This page features a simple, three IC unipolar stepper motor driver that can be used to drive relatively low speed applications at currents up to 1 ampere per phase. The circuit is made with parts that are available from a variety of sources.

Stepper Motor Driver

BIPOLAR Stepper Motor Driver - 2008 (74194)

  This page features a Bipolar stepper motor driver using three ICs. The circuit can be used to drive relatively low speed applications at currents up to 1.0 ampere per phase. The circuit uses parts that are available from a variety of sources.

Stepper Motor Driver

Photo Detector Circuits

  This page features basic, visible light photodetector circuits that can be used to detect trains. These methods would normally be used with the photo sensor mounted between the rails.

Photocell and Phototransistor - Detector Circuit     en français

Capacitor Discharge - Switch Machine Power Supplies

  This page presents various capacitor discharge power supply circuits for use with twin coil switch machine motors. Also shown are some optional wiring methods that can be used to enhance the availability and control of these supplies.

Switch Machine Power Supply    en français

Integrated Circuit Pinout Diagrams

  The following diagram shows the pinouts for some of the integrated circuits and transistors used on these pages.

Integrated Circuit and Transistor Pinout diagrams

Basic - Infrared Light - Train Detection

  This page presents information on infrared - 'Above And Across The Track' train detection circuits. The circuits are designed around the LM339 comparator chip and can use a wide assortment of matched infrared - emitter / detector pairs.

Above And Across Track Detection

Grade Crossing Flasher Light Circuits

  The following are Low Power - Grade Crossing Flasher circuits based on the LM555 and LM556 timer chips. They are designed to drive Light Emitting Diodes but could be used to drive low current incandescent lamps.

Crossing Light Flashers information    en français

Wire Coat Hanger Cable Guides

  Here is a way to use old wire coat hangers to make simple and efficient wiring harness guides that can help keep your layout wiring neat and tangle free.

Coat Hanger Cable Guide    en français

Model Railroad Odometer Car

  This page features a photo and schematic from an article that was published in the August 1994 issue of Model Railroader Magazine. The article was titled "Build a model railroad odometer car".

Model Railroad Odometer Car

Day and Night Infrared Detection

  The following is a method to allow day and night detection using Infrared/Visible light sensitive phototransistors and a simple LM339 voltage comparator circuit.

Day and Night Detection

Rail Crossing Diamond Protection Circuit

  The Crossing Diamond Protection circuit is designed to prevent collisions where one rail line crosses another. Using phototransistor sensors to detect a train the circuit will disconnect the track power from the line that crosses the occupied line.

Rail Crossing Diamond Protection

Turnout Anti-Derail Protection

  The circuits presented here will prevent turnouts from being thrown while a train is on the switch, ideal where the switch cannot be seen by the operator. They use phototransistor sensors to detect the train and have a short time delay to compensate for gaps between cars. The circuit can also be used to protect crossovers and ladder tracks with the addition of more sensors.

Turnout Anti-Derail Protection

Audible Train Approach Warning

  This is a circuit that will give an audible warning that a train is entering a particular section of track. The detector also has a LED that indicates when a train is entering or leaving the block.

Audible Train Approach Warning

Automatic Incline Railway System

  The drawings and photos below are for an operating incline railway that was built by the London Model Railroad Group for its 'O' scale model railway club located at London, Ontario, Canada. This is a single car model loosely based on a double car incline that operated at Port Stanley, Ontario.

Incline Railway Circuit

Various Transistor Throttle Circuits

  This page will show a number of variations on DC, transistor type throttles. The throttles range from 'tried and true' types to 'experimental' designs.

Transistor Throttle Circuits (Top of Page)

A Three Terminal Regulator Type Throttle

  The schematic above is of a Three Terminal Regulator (TTR) design based on a LM350K regulator which has a 3 Amp current rating as opposed to the LM317K with a 1.5 Amp rating.

TTR Throttle Circuit    en français

Silicon Controlled Rectifier Type Throttles

  The following is a schematic drawing of a Silicon Controlled Rectifier type throttle for use on larger scale model railroads. Three versions of this throttle are shown on this page. They are not sophisticated designs but work well and are tough and reliable.

SCR Throttle Circuits

Solid State Relays

  The following are examples of home made solid state relays that could be used to replace mechanical types in many model railroad circuits.

Solid State Relay    en français

5 Times Around Circuit for Layout Animation

  The 5 Times Around circuit was designed to automatically let an N Scale locomotive and car travel around a loop 5 times and stop for approximately a minute and then repeat the cycle.

5 Times Around Circuit

Voltage Comparator Circuits

  This page will provide some basic information about voltage comparator integrated circuits and and to act as reference material for other circuits. These circuits are based on the LM339 Quad Voltage Comparator chip.

Voltage Comparator

Regulated Power Supply Circuits

  The circuits on this page are for various type of voltage regulated power supplies.

Power Supply     en français

An Ammeter Made From A Voltmeter

  The Circuit is for a 'Shunt' type ammeter that allows a meter movement with a small current rating to be used to measure a much larger current. In this example 1 milliamp through the meter coil will represent 1.5 amps by shunting most of the current through the 0.1 Ohm resistor.

Shunt Ammeter Circuit

Science

  Some diagrams related to various aspects of science in general.

Science

Circuits Without Pages Of Their Own

  The circuits in the following list do not have a specific page dedicated to them. The schematics have very little, if any explanation accompanying them. Some of the circuits are experimental in nature.

  The circuits in this group are:

  1. Cascade Delay Circuits Using 556 Slow-Motion Switch Machine Drivers

  2. Common Cathode LEDs To Common Anode LEDs Signal Driver Adapter

  3. Ir Receiver Modules for 37 to 58KHz

  4. Trackside Camera Flash Circuit (LM555)

  5. HIGH or LOW power switch

  6. DCC Booster Anti-Fault Transistion Block

  7. Ash Pit Dimmer

  8. 2 Sets Of 2 Inputs To 4 Discrete Outputs

  9. Roundhouse Track Power Cutoff Circuit

  10. 7474 Bipolar Stepper Driver Generators

  11. DCC - Inrush Current Limiter

  12. AC Only - Block Occupancy Detector

  13. ULN2803 H-Bridge Circuit

  14. 3 Level Battery Voltage Alarm

  15. Low Voltage Power Supplies For LEDs Or Lamps

  16. Lighting Circuits For Locomotives

  17. Current Regulators For Light Emitting Diodes

  18. RC Servo Motor Test Circuit (LM555)

  19. High Current Switch Machine Motor Driver    (Fulgurex® Machines)

  20. PUJT & Voltage Comparator - Power On - Delay Circuits

  21. PIR Video Camera Control

  22. Team digital - SCR16 - Twin Coil Switch Machine Adapter

  23. N.O. Magnetic Reed Switch ON /OFF Circuit (SCR Equivalent)

  24. Preselect Twin Coil Switch Machine Circuit

  25. UNIPOLAR Stepper Motor Driver - Power Miser Version

  26. Model Railroad - Infrared Proximity Switch (2005)

  27. Back And Forth Stepper Motor Driver

  28. 5 Second Ramp Generator

  29. LM311 Thermostat Circuits

  30. Adding Meters to DC Throttles

  31. DCC To DC Power Supplies For Accessory Circuits

  32. Train Mounted Camera Battery Charger

  33. 10, 8 And 6 Step LED Circuits (CD4017)

  34. LED Out Circuits For Tortoise Switch Machines

  35. Snubber Diodes Across Relay Coils

  36. School Bus Signals Circuit

  37. Grade Crossing Bell Ringer (LM555)

  38. Using Common Cathode Or Anode Leds As Bipolar LEDs

  39. Transformer Secondary Voltage Reduction

  40. Incandescent LED Circuit

  41. Bad And Good Circuit Board Solder Joints

  42. High Side Current Monitors (ZXCT-1009)

  43. Light Activated Detector Circuit (LM393/LM555)

  44. Special Function Timer Circuits (LM555)

  45. Timed DC Throttle

  46. Various LED Blinker Circuits

  47. Finding Bad Joints In Track Wiring

  48. Current Vs. Voltage For Various Automotive Lamps

  49. Timed Uncoupling Ramp Driver (LM555)

  50. Grouped DCC Block Occupancy Detectors

  51. High Impedance Voltmeter Adapter

  52. Finding The Resistance Of Meter Coils

  53. DCC - Zero Stretching Simulator (LM555)

  54. Push Button Stop / Start Motor Control Circuits

  55. Colour Shifting for Bi-Colour LED's (LM555)

  56. Using 1 Transformer For 2 Throttles - Why It Cannot Be Done

  57. CA4060B Timer Circuits

  58. Low battery Voltage Cutout Circuits

  59. First Across The Line - Race Timers


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The Circuit Index Page Fine Print Section

  N.B. - The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Above And Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.

  If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.

  Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.

  All HTML code, images, and page design, hereafter referred to as "content," contained within this site are the copyrighted property of Rob Paisley, and can not, under any circumstances, be cached, retransmitted, copied, or altered without his explicit written permission, in which case, he shall be acknowledged as the copyright holder and author.

  Unless specifically stated in a written contract, Rob Paisley grants no license to any party for the use of the content in this site for the manufacture and sale of goods, nor any other commercial utilization.

  Rob Paisley assumes no liability for any damages, direct, or consequential, which may arise from the dissemination, application, or misapplication of the content contained in this site. The User of the information provided in this site assumes all responsibility for any damages, direct or consequential, which may arise from its use. Rob Paisley retains the right to alter the content within this site at any time without notice.

  References to registered trademarks within this page are provided for informational use only, and are not intended as an endorsement for any service or product. Any such trademarks are the property of their respective owners.

  By clicking the links on this site, you, the User agrees to the above stated terms.


Recent Revisions And Updates To This Site

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Voltage Comparator Information And Circuits - Added To - April, 2014

LM555 Timers - Circuits and Calculators - Section 19 Added To - March, 2014

556 Timer Stall-Motor Switch Machine Driver (PCB) - Alternating Output Circuit Updated - March, 2014

Circuits Without Pages Of Their Own <--> Full List of Circuits Here

2011 - Grade Crossing Circuit (PCB) Four-Quadrant Gate Control Added - January, 2014

Rail Crossing Diamond Protection - Updated - December, 2013

Toggle Switch Control Of Twin Coil Switch Machines - Relay Control Added - September, 2013

Toggle Switch Control Of Single Coil Switch Machines - Relay Control Added - September, 2013

EDE1200 - UNIPOLAR Stepper Motor Driver (PCB) - New - September, 2013

Various Transistor Throttles - Section 9 Added - August, 2013

Automatic Reversing and Station Stop Circuits - FWDC Output Schematic Added - April, 2013

Automatic Reversing and Station Stop Circuits - Circuit Boards Available - April, 2013

Retrofitting Garden Lights With LEDs Using License Plate Lights - February, 2013

Cam Action - Swing Gate Illustration - February, 2013

556 - Searchlight Signal Circuits (PCB) - Updated - February, 2013

3 Light - Model Railroad Block Signal Circuit (PCB) - Updated - February, 2013

London Model Railroad Group (2006)


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Making Contact

email - rpaisley4@cogeco.ca

25 March, 2014