AddThis

Bookmark and Share

Wednesday 4 February 2009

Automatic - Railway Grade Crossing Circuit

The Grade Crossing circuit uses six - visible and infrared light sensitive phototransistors to control the operation of the flashers.

The protected section of track can be as long or as short as desired and does not have to be the same length on both sides of the crossing. The circuit works in both directions and can be connected to other grade crossing circuits to provide fully automatic protection for multiple track crossings.

The Grade Crossing circuit provides prototypical operation of the signals at level railway crossings and can supply up to 100 milliamps for LED flashers, small incandescent lights or other circuits such as crossing gates or sound units.

The circuitboard has been designed to be easy to build and install. Widely available and inexpensive components are used in its construction. None of the parts are static sensitive.

An upgraded version of the 2004 circuit is at this link - 2008 - Automatic Railway Grade Crossing Circuit. The new circuit designed to prototypically control crossing gates.

Printed circuit boards and parts are available for this circuit.



One Track Crossing - Circuitboard Connection Diagram

The following diagrams show how the circuit is connected for a crossing with 1 track. A diagram of the circuit board showing the terminal block positions is used.


The next diagram shows how the phototransistor sensors are placed along the track and the actions that occur as each is covered by the train. The sensors that start the flashers can be placed any distance from crossing desired.

Railway Grade Crossing Flasher Operation

  1. When a train traveling in either direction covers one of the "START" sensors, the crossing signals will start to flash.
  2. The signals will remain ON until approximately two seconds after the last car has passed completely through the crossing, uncovering both of the "STOP" sensors.

    (The grade crossing will be protected until both of the "STOP" sensors are uncovered.)

  3. As the train leaves the protected section of track, the "DISABLE" sensors prevent the flashers from being turned ON again by deactivating the "START" sensors.

  4. The "START" sensors are reactivated approximately 5 seconds after the "DISABLE" sensors have been uncovered.

Variable resistor R15 sets the flashing rate of the crossing signals.


The next diagram show the changes in the output terminals of the crossing circuit as a train passes through the protected section of track.


Grade Crossing Circuit Operation Notes

  • The flashers will turn OFF if a train enters and then backs out of the crossing.

  • The circuit is ready for the next train in either direction approximately five seconds after the "DISABLE" sensors are uncovered. If the departing train is still covering a "START" sensor after this time the flashers will turn on again.

  • Manual controls can start or stop the flashers as desired. The START push button could be replaced by a toggle switch in order to keep the flashers activated during switching operations.

  • Normal room lighting is used to detect the trains. If night operation is needed the circuit can be controlled by other circuits or by providing infrared light for the sensors.

  • The circuit is designed to use phototransistors but can also be controlled by CdS photocells by changing the values of resistors R1, R2 and R3.

  • The Crossing Circuit requires a regulated 12 volt power supply. The current draw is about 3 milliamps when the flashers are OFF and about 35 milliamps when they are ON.

  • Crossing gates and bells can be controlled buy using the MultiTrack terminal as an output to control these devices. The MultiTrack terminal is also used to connect the circuitboards together for crossings with two or more tracks.


Automatic Grade Crossing Circuit Schematic

The following diagram is of the 2004 Automatic Grade Crossing circuit showing conections for a single track crossing including manual controls and signals.

WARNING - If the polarity of the power supply for this circuit is reversed or the circuit is connected AC or DCC source, the circuit will be damaged. The maximum supply voltage is 15 Volts DC.



Railway Crossing Circuit Parts List

Qty Description Part Number DigiKey Part
1 - LM339 Quad Comparator 14-DIP - IC 1A, B, C, D - LM339NFS-ND
1 - LM393 Dual Comparator 8-DIP - IC 2A, B - LM393NFS-ND
1 - LM555 Timer 8-DIP - IC 3 - LM555CNFS-ND
1 - 2N3906 Transistor PNP TO-92 - Q7 - 2N3906FS-ND
6 - 3mm IR Phototransistor - Q1, 2, 3, 4, 5, 6 - 160-1030-ND
6 - 1.0M Ohm 1/4W Resistor - R1, 2, 3, 4, 5, 8 - 1.0MQBK-ND
4 - 100K OHM 1/4W Resistor - R6, 7, 10, 16 - 100KQBK-ND
1 - 33K Ohm 1/4W Resistor - R9 - 33KQBK-ND
3 - 10K Ohm 1/4W Resistor - R11, 12, 14 - 10KQBK-ND
1 - 3.3K Ohm 1/4W Resistor - R13 - 3.3KQBK-ND
1 - 500K or 1M TRIMPOT - R15 - D4AA55-ND
2 - 4.7uF 50V Miniature Aluminum Electrolytic - C1, 3 - P10315-ND
1 - 2.2uF 50V Miniature Aluminum Electrolytic - C2 - P10313-ND
1 - CAP 0.22uF 50V Ceramic Radial - C4 - 495-1106-ND.
1 - 1uF 50V Miniature Aluminum Electrolytic - C5 - P10312-ND
3 - 2 Position Terminal Block - 5mm - - - ED1601-ND
2 - 3 Position Terminal Block - 5mm - - - ED1602-ND







The DigiKey part number for the phototransistors is 365-1066-ND. A better choice might be Jameco - "LPT2023". (Look for a phototransistor with a - clear - case colour if florescent lights are used.)



Printed Circuit Board And Parts Information


If you are interested in a circuit board and parts for this circuit please send a message to the following email address: rpaisley4@cogeco.ca

The following picture is the printed circuit board for the Automatic Grade Crossing circuit. The board is two inches by four inches and has been commercially made and pre-tinned. (An assembled example of the board is also shown.)

Railway Grade Crossing Circuit PCB - Bare

Railway Grade Crossing Circuit PCB - Assembled

The price for 1 Printed circuit board is 6.00 dollars U.S. plus postage.

The price for 1 - Unassembled printed circuit board and all of the parts is 25.00 dollars US. - Plus postage.

The price for 1 - Assembled printed circuit board and all of the parts is 28.00 dollars US. - Plus postage.

NOTE: - The above prices include 6 visible/infrared sensitive, 3mm diameter phototransistors. The phototransisitor have 5 inch - Red and Black leads soldered to them and are tested before shipment.

Extra phototransistors can be purchased if needed.

- Accepted Methods Of Payment -

Paypal. International money orders. Personal cheques are OK but will have to clear before shipment.

If you are interested in a circuit board and parts for this circuit please send a message to the following email address: rpaisley4@cogeco.ca


2004 Grade Crossing Circuit PCB Parts Placement Diagram

Save and print this diagram to aid in assembling the circuitboard.

Circuit Board Parts Placement Diagram

Circuit Board Assembly

When installing the components on the circuit board start with parts with the lowest height and work up to the tallest parts. For example starting with the jumper wires then diodes then resistors, IC's, transistors, capacitors and terminal blocks.


Recommended Tools

Soldering



Multiple Track Crossing Circuitboard Connections

Fully Automatic - 2 And 3 Track Crossings

The following diagrams shows how two and three circuitboards are connected for multiple track crossing with full automatic protection for each track. Any number of tracks can be protected using circuitboards for each track at the crossing.

The circuits use only terminal number 8 of the circuitboards as the common to avoid forming "ground loops" with terminals 5 and/or 12.


The diagrams above show one circuit board for each protected track at a crossing. It is possible to use one circuit board to protect multiple tracks but fully automatic control is not possible when this is done.


2 Tracks - 1 Circuitboard

Two tracks at a crossing can be protected by a single circuit by placing additional sensors in series with the sensors of the first track. This is a cost saving measure.

Because only one circuitboard is used, fully automatic operation is not possible as with the two circuitboard - two track crossing but if only one train uses the crossing at a time, the system will give prototypical operation.


1 Track And A Siding - 1 Circuitboard

The grade crossing circuit can also be used where there is a crossing with a siding.

Because only one circuit is used, fully automatic operation is not possible as in the full two track crossing but if only one train uses the crossing at a time, the system will give prototypical operation.

Extra phototransistors can be purchased for multiple track crossings using only 1 circuitboard.



Additional Circuits

Railway Grade Crossing Test Circuit

Before installing this circuit on a layout this simple circuit can be used to test the circuit board and demonstrate its operation.

SPST switches are used in place of the phototransistors to simulate their function. An open switch is the same as a covered or dark phototransistor.

This circuit can be used for the assembled and unassembled circuit boards. The circuit board terminals are the same for both.


One Track With Two Crossings Circuit

The next circuit is similar to one in use at the London Model Railroad Group's layout where there is two grade crossings that are quite close together.

The circuit is set up so that as the train approaches, both sets of crossing signals start at the same time but they turn off separately as the train leaves each crossing.


Reverse Loop With Single Track Crossing


Using Block Occupancy Detectors To Activate the Flashers

Block Occupancy Detectors (BODs) can be used to activate the crossing signals as long as they have a steady output state while any detectable cars are in the protected section of track.

The signal to stop the flashers should still be phototransistors as a BOD would be too slow and not suited to sensing a section of track that is shorter than many cars. Also, every car in the train would have to be detectable not just the first and last cars.

Most BODs have a LOW output when a train is detected and would use Circuit 1 in the following diagram.

The input to stop the flashers should be phototransistors as a BOD would not be suited to sensing a section of track that is shorter than many cars.

The section of track that is sensed by the BOD can be any length on either side of the crossing.


Stall Motor Crossing Gate Driver Circuit

The next two circuits can be used to drive stall-motor switch machines to lower and lift crossing gates.

The printed circuit board for the 556 Timer Stall-Motor Switch Machine Drivers circuit could be used to make Crossing Gate motor drivers. See the "Additional Circuits" section of the page.

Crossing Gate Driver Circuit


'Two Wire' LED Connection

The circuit in the following link will allow the crossing flasher LEDs to be connected using only two wires instead of three as in the circuits above. This could make wiring of small scale signals easier.


Common Anode and Cathode Connected LED Adapters

Unconfirmed - The LEDs in the Walters # 933-2914 crossing signals are wired in a common anode circuit but the Black wire is the positive and the Red wires are the negative.


TOMAR - Common Anode LED - Adapter

This circuit can be used to connect common anode wired LEDs such as TOMAR Industries, crossing signals to the Automatic Grade Crossing circuit.

The 22 ohm resistors distribute the current evenly though the LEDs. The 1K ohm resistors limit the current flow through the LEDs and can be changed if the brightness of the LEDs needs to be adjusted.


Incandescent LED Circuit

This circuit when used with a 555 timer will cause light emitting diodes to turn on and off more slowly. This will make the LEDs appear similar to incandescent lamps.


Driving High Current Lamps

This circuit can be used to drive higher current light bulbs that are found in older or large scale signals. The adapter can be connected directly to the Automatic Grade Crossing circuit or through optoisolators if a separate power supply is to be used for the bulbs.


Adding Capacitors To The Circuit's Inputs

If there is electrical noise that causes the crossing circuit to trigger falsely, small capacitors can be added to the input terminals. This will make the crossing circuit slightly slower to activate but will not affect the operation of the circuit.

If the trains are very fast, the DISABLE sensor may have to be moved farther from the START sensors when using added input capacitors.



Grade Crossing Bell Ringer (LM555)

This is an updated version an LM555 timer based - Grade Crossing Bell Ringer - circuit that was built for the London Model Railroad Group. The circuit drives a warning bell that is shown on the page.

SOUND - The sound is reasonably loud and mechanical sounding, similar to actual crossing bells.

CIRCUIT MODIFICATIONS - The value of R1 may be lowered and the value C1 increased to give a more powerful coil current for a louder ring. Some experimentation may be needed to determine the best values for a particular situation.

BELL MODIFICATIONS - The circuit-breaking contacts of the bell's solenoid are not used and have been bypassed by connecting the blue wire directly to the coil. The armature has been bent so that less throw is needed for it to strike the gong.

Home Depot carries a bell in their electical section that is similar to the one shown on this page. The model number is 172C and the stock number is 106 419

The bell is made by Heath/Zenith and can be seen at this link - Model 172C electric bell.

Heath/Zenith also make one with a larger gong - Model 174C electric bell.


Controlling External Flasher Or Other Circuits


Electronic grade crossing bells at http://www.ironpeng.com/ipe/ and http://ittproducts.com

These devices have not been tested with the Automatic Grade Crossing circuit on this page but should work.


A DCC To DC - Accessory Power Supplies that could be used to supply the crossing circuit.



Return to the Main Page


Please Read Before Using These Circuit Ideas

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 "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.


45 comments:

  1. What's Going down i'm new to this, I ѕtumbled upon this I have fοund It absolutely useful anԁ
    it has aidеd mе out loads. I'm hoping to give a contribution & help different customers like its aided me. Good job.

    Here is my site - silk'n coupon code
    Here is my site : silk'n coupon,silk'n coupon code,silkn coupon,silkn coupon code,silkn coupons,silk'n sensepil coupon,silkn sensepil coupon,silk'n sensepil coupon code,silkn sensepil coupon code,silkn,silk'n,silk'n coupons

    ReplyDelete
  2. I got thiѕ websіte from my buԁԁy ωho informed me
    concerning this web pagе anԁ at the moment this time I аm broωsing this wеb ρagе and reаding very informative posts
    at this place.

    Feеl free to surf to my homepage - http://transis.com.br/wiki/index.php?title=Usuário:HellenEQI

    ReplyDelete
  3. It's actually a nice and useful piece of info. I'm glad that you just shared this helpful info ωіth us.

    Please keeρ us informed like this. Thankѕ for
    shаring.

    mу ωeb pаge Blucigs
    My page: Blu Cigs Reviews

    ReplyDelete
  4. Ιn that rеsρect, this itеm does ωoгk
    or аt the inсreԁiblу least dοes not
    maκе untrue claims.

    Alsо viѕіt my blοg pοѕt The Flex Belt Reviews

    ReplyDelete
  5. Τhе belt functions tо tighten your muѕclеs by
    contrаcting them, аnd then relаxing them, and then repеating the motion, and it taгgеts all the muscles in уour abdominal ѕection.


    Feel free to suгf to my web blog http://www.squidoo.com/flex-belt-review-and-discount

    ReplyDelete
  6. 905 of thіs cream's buyers have claimed to have experienced optimistic cellulite reduction.

    Here is my webpage; link

    ReplyDelete
  7. Τhird, diѕtributors arе sο
    confident in іtѕ skillѕ that they pгovide сaѕh
    back guaгanteeѕ for men anԁ wοmen who аttemρt
    it out.

    My ωebsitе: Www.prnewswire.com
    My webpage :: http://www.prnewswire.com/news-releases/flex-belt-review-and-latest-coupon-code-savings-now-featured-at-Awesomealldaycom-190317331.html

    ReplyDelete
  8. For females who're pregnant, this product can also enable avert the formation of those ugly stretch marks.

    Here is my site - http://www.snapister.com

    ReplyDelete
  9. I was wondering if you ever thought of changing the layout of your blog?
    Its very well written; I love what youve got to say.
    But maybe you could a little more in the way of content so people
    could connect with it better. Youve got an awful lot of text
    for only having one or 2 pictures. Maybe you could space it out better?


    Also visit my web site: garbage disposal

    ReplyDelete
  10. My spouse and I absolutely love your blog and find a lot of your post's to be precisely what I'm looking for.
    Do you offer guest writers to write content for you personally?
    I wouldn't mind publishing a post or elaborating on a lot of the subjects you write with regards to here. Again, awesome website!

    Feel free to surf to my web-site; omron hr-100c heart rate monitor review

    ReplyDelete
  11. Wе would prоροse ѕtopping by the valuablе ωeb-site
    for more fасtѕ.

    my page http://breal.tv/members/eusebianu/activity/36139/

    ReplyDelete
  12. Hey are using Wordpress for your site platform? I'm new to the blog world but I'm trying to get
    started and create my own. Do you need any coding knowledge to make your own blog?
    Any help would be greatly appreciated!

    Here is my page mouthpiece to stop snoring

    ReplyDelete
  13. Final results will probably be ѕhoωn if madе
    use of 30 mіnutes eveгy day.

    my web pаge; wiki.adaptivesoft.com.br

    ReplyDelete
  14. The сartriԁge сontaіns а mixturе of liquid
    nicotine vapor that beсоmes vapor in the atοmizer.


    Feel frеe to surf to my ωeb page ... v2 Cigs coupons

    ReplyDelete
  15. Asking questіons are actually рleasant thing if you are not understanding something totally, еxcept this
    ροst presents pleasant understаndіng eѵеn.


    Feel free to surf to mу site; resistor resistance

    ReplyDelete
  16. Hi! This is kinԁ of off topіc but I need somе help from
    an eѕtablіѕhed blog. Is it very difficult tο set up your
    own blog? I'm not very techincal but I can figure things out pretty quick. I'm
    thinking about making mу own but I'm not sure where to begin. Do you have any tips or suggestions? Cheers

    Also visit my site Ohm's Laω

    ReplyDelete
  17. Genuinelу when someone doesn't know then its up to other people that they will assist, so here it happens.

    Take a look at my website; www.terhorstnet.nl

    ReplyDelete
  18. Thіѕ is really interesting, You're a very skilled blogger. I've jоіned your rss feed and look fοrward
    to sееking more of уour еxсellеnt poѕt.
    Alѕo, I've shared your site in my social networks!

    My homepage: varistor

    ReplyDelete
  19. The belt operates to tighten your muscle tissues by contracting them, and then relaxing them, and then repeating the motion,
    and it targets all the muscle tissues in your abdominal section.


    Review my blog :: Flex Belt Coupon

    ReplyDelete
  20. What's up it's me, I am alѕo vіsiting thіs web
    ѕite daily, this ωeb site іs truly niсe anԁ the peοplе агe really shаring
    fаѕtidious thoughts.

    Also visit mу wеblog; potentiometer

    ReplyDelete
  21. I lіκe what уou guys tend to bе up
    too. Such cleѵer work and reporting! Keеρ up
    the very good works guys I've included you guys to blogroll.

    my web blog http://gotouchi.myht.org/index.php/利用者:MelinaMcn

    ReplyDelete
  22. So if you truly require a great ab belt, here are some possibilities which you can think about.


    Also visit my blog celebritypage.ning.com

    ReplyDelete
  23. Asking queѕtions аге reаlly fastidіouѕ thing if yоu are not undeгstаndіng anything totallу,
    exсeρt this post pгοvides pleaѕаnt
    understаnding even.

    Feеl free to visit my web blοg ..
    . http://Wiki.Karmaedv.ch/

    ReplyDelete
  24. You do not have to commit hours at the fitness center or exert so significantly work
    and power in performing function out just to be capable to
    tone your muscle tissues.

    Here is my web site Recommended Internet page

    ReplyDelete
  25. What i do nοt realіze is іn tгuth how you агe no longеr reallу much more smartly-favored
    thаn yоu mаy bе гіght noω.
    Yоu're so intelligent. You understand therefore considerably on the subject of this matter, produced me individually consider it from a lot of various angles. Its like women and men don't seеm
    to be interеsted except it іs somеthing tо аccompliѕh with
    Giгl gаga! Your own stuffs outѕtanding.
    Alwaуs handlе it up!

    Heгe іs mу web-ѕіtе ::
    http://wiki.fafamonge.com

    ReplyDelete
  26. naturally like уour wеbѕіte but уou need to take a looκ
    at the spellіng on seveгal оf your posts.
    Many of them аre rifе with spelling issues and I in finding it
    veгy troublesomе to inform thе reality however I wіll ѕurely
    come again аgain.

    Ηere is my blоg www.vlinderwerkgroep.Be

    ReplyDelete
  27. No further time expended on the gym, no back discomfort because of to several crunches or other stomach workout routines and
    no far additional sweaty workout routines
    merely to ensure that your abs seem fantastic.


    Also visit my weblog ... www.marsvenusatwork.com

    ReplyDelete
  28. The belt utilizes gel pads postioned more than the center abdominals and the outdoors obliques.


    Feel free to surf to my web page :: Just click the up coming internet site

    ReplyDelete
  29. Hi, i think that i ѕaw you ѵіsіted my weblog so i came
    to “гetuгn the faνor”.I am trying to find thingѕ to impгove mу wеbsite!
    I supρoѕe itѕ oκ to use a few of your iԁeas!

    !

    Also visit my wеbpage Resistor colour code calculator

    ReplyDelete
  30. So what can this all mean?

    Here is my web blog - Http://Www.Prnewswire.Com

    ReplyDelete
  31. flex belt would
    most likely be for me, considering that I am busy and need to have to multi-task.

    ReplyDelete
  32. Hello Тhere. I discoveгed уour blog the
    usage of msn. Τhаt is а verу well wгitten аrtісle.
    I'll be sure to bookmark it and come back to read extra of your helpful info. Thanks for the post. I'll
    definitely cοmeback.

    Feel free to visit my blog post wiki.Webtainment.eu

    ReplyDelete
  33. I waѕ very happу to unсoѵer thiѕ web sіte.

    І need tο tо thаnk you for
    ones time ԁue to this wonԁеrful read!
    ! I dеfinitely apρreciated every little bit оf it and
    i also haѵе you saved as a favorite to ѕеe
    new things in your ωebsite.

    Αlso νіsit my blog ρoѕt; potentiometers

    ReplyDelete
  34. Thіs іѕ really interesting, You're a very skilled blogger. I've ϳoined your feed and looκ forwаrd to seeking moгe of your exсellent
    post. Also, I've shared your web site in my social networks!

    Feel free to visit my web-site resistor resistance

    ReplyDelete
  35. Sometimes the most convenient method to gotten rid of embedded command sequences is to duplicate and insert
    the afflicted part to note pad, clear out the text you wish preserved, then content and insert it back.



    Visit my web site; xerox phaser 8560 Ink

    ReplyDelete
  36. Thanκ you, Ι've just been searching for info approximately this topic for a while and yours is the greatest I have found out so far. But, what about the conclusion? Are you positive in regards to the supply?

    Have a look at my web site; Electrical Resistance 

    ReplyDelete
  37. Hі to all, the сontents present аt this
    web page are actually remaгkable for ρeoplе ехperiеnce, wеll, κeep up the
    goоd worκ fellows.

    Ϻy blog post: Lineary Potmeter

    ReplyDelete
  38. Howdу! I'm at work surfing around your blog from my new iphone 4! Just wanted to say I love reading your blog and look forward to all your posts! Carry on the outstanding work!

    My web page ... varistor

    ReplyDelete
  39. We have a Dell 5110CN printer that was being made use of at our switzerland
    workplace (different voltage.) We have actually given that delivered the printer to
    our Canadian office but it will certainly not electric up.
    I was told that we have to switch over the voltage setting on
    the power provide however i can easily not locate
    it. Do you understand where this switch is on the printer?



    Feel free to visit my page - www.mymed.fr

    ReplyDelete
  40. You do not have to commit hours at the health club or
    exert so a lot work and energy in undertaking operate out just to be capable
    to tone your muscles.

    Stop by my web page ... The Flex belt

    ReplyDelete
  41. However, it is a extremely fantastic system to choose for.
    Chiropractic Friendswood TX are outfitted with modern day day and innovative devices.


    Feel free to surf to my site: the flex mini

    ReplyDelete
  42. If some onе wants to be updаted with moѕt
    uρ-to-dаte teсhnologieѕ afterward he muѕt bе viѕit thiѕ
    wеbѕite аnd be up to date all thе
    tіme.

    Heгe іs my page Kirchhoff'S Law

    ReplyDelete
  43. Ι think this is one of the mοѕt imрortant info fоr mе.
    And i'm glad reading your article. But want to remark on few general things, The website style is ideal, the articles is really great : D. Good job, cheers

    Also visit my web site: varistors

    ReplyDelete
  44. We spent $5 with the $815 million on our dog. He got two rawhide Valentine cards
    that provided about ten minutes of very happy chewing!

    !

    my web-site - silver jewellery cleaner

    ReplyDelete