• Skip to main content
  • Skip to primary sidebar

Making Easy Circuits

Learn and build electronic circuits

You are here: Home / Hobby Projects / Automatic Signalling Circuit for Model Trains

Automatic Signalling Circuit for Model Trains

Last Updated on January 10, 2018 by Admin 4 Comments

Automatic railway signals are meant for efficient movement of trains, without colliding. The track is divided into blocks or sections. At the entry of each section there is a signal. The signal consists of three lights-red, amber and green in colour. Red light means the train should stop totally, because another train is in the next block. Amber means the train is to proceed slowly as another train is in the tracks one block ahead. Green means the train can shoot straight ahead as next two blocks are unoccupied, i.e. the line is clear. When there is no train anywhere; all signals should be green. But when the train is in' one particular block, the signal for that block should turn red while signal for the previous block should turn amber. And these red and amber signals should change as the train moves to the next block. As manual working of the signals cannot be efficient enough, an automatic signalling system is required. This circuit is built around TTL gates. Each block requires two inverter gates (7404 or 7406) and two OR gates (7432). Rail C is, the common rail for the entire track having electrical continuity all along the track. Bl, B2 etc are the block rails. B1 is not directly connected to B2, B3 or B4. C rail is connected to positive end of SV DC supply. Eachblock rail is connected to negative side of the supply through 22k (or 47k) resistors. The actual value of the current- limiting resistors does not matter so long as they keep the current to a low level. To B1 may be connected the input of two inverter gates. One will drive the red signal of block 1 and the other will drive amber signal of previous block, i.e. block 4. - To B1 one input each of OR gates operating green signalsof blocks 1 and 4 may also be connected. The other end of OR gate operating green signal of block 1 is connected to B2 and of OR gate operating green signal of block 4 is con- nected to BQ. The pattern is repeated for all other blocks. The output of OR gate drives green LED through 220- ohm resistor, and outputs of inverter gates drive the red and amber LEDs. Each gate has current sinking capacity of 16 mA. Hence separate inverter gates are used for red and amber lights so that about l0mA can be safely-sunk in each. When there is no train anyvvhere, all blocks (Bl to B4) are at ‘low’ level. So all OR inputs are ‘low’ and all OR outputs are also ‘low’. Therefore, all green lights will glow. And since all inverter inputs are at ‘low’ level, all inverter outputs are at ‘high’ level. Therefore, allred and amber lights Will be off. When train is in block 1, it will short C rail to B1, and so Bl will be at logical ‘high’ level. Thus one input each of OR gates for block l and block 4 will be at logical ‘high’, and outputs of these two will also be at logical ‘high’. Therefore, green lights Gl and G4 will be off. Also, inputs for inverter gates controlling A4 and Rl will be at logical ‘high’, and so their outputs will be at logical ‘low’. Therefore LEDs Rl and A4 will glow. When the train proceeds to blocks 2, it will switch R2, Al and G4 on, while G2 and Gl will be switched off. Thus the train will automatically go on changing signals while moving. Any power supply regulated by lC 7805 will do. As tht circuit does not require more than 150 mA, a 250mA trans- former will do. A Signal poists" may be constructed using a black bakelite strip l cm wide and 5 to 6 cm liigh. LED holders can be fitted on it for mounting LEDs. ‘ - Red, green and yellow colored wires may be used for wiring, and these may be neatly laid beside the track to add to its decorative value.

 

model train controller circuit

 

 

 

 

model train IC pinouts

Hints

l. lt is convenient to lay a closed track; it allows the train to move continuously. But closed tracks available with the train are too short in length. To increase the length of the track, use ‘T’ sections used as guide rails for sliding shutters used in cupboards. 2. The toy train used was ‘Taj Express’ which has a man- ual start and stop system. 3. By adding one inverter gate to each block we can set up a cabinman’s train position indicator. For this fix an LED in each block and let theacorresponding added inverter gate drive the LED. Thus the lit LED will indicate the position of the train. ,

You'll also like:

  • 1.  20 Best IC 741 based DIY Circuits
  • 2.  Simple CMOS IC Circuits
  • 3.  Chirping Bird Circuit
  • 4.  Horse Pace Sound Simulator Circuit
  • 5.  How to Make a Sequential Delay Timer Circuit
  • 6.  Simple SCR Circuits

About Admin

Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
If you have any questions related to this field, please do not hesitate to drop a comment! I am always here and ready to help you out with any queries you might have. I cannot wait to hear from you!

Reader Interactions

Comments

  1. David c. says

    April 24, 2025 at 10:27 am

    There is a much simpler way to build an abs system, with only one chip and no dropping resistors. This is accomplished by using negative logic and a 7400LS per head. All the led,s, are common anode. A resistor can be used on the anode of each signal head, to decrease the briteness if one desires.
    East and westbound are driven straight off the detector.

    Reply
    • Admin says

      April 25, 2025 at 9:01 am

      Thank you for the interesting information!

      Reply
  2. Don Mills says

    March 8, 2017 at 6:41 pm

    Not sure if you are aware, in the article about building an Automatic Signalling Circuit for Model Trains, you show two wiring diagrams at the bottom of the page. When clicked, the first diagram can be seen in a larger image. However, when you click the second wiring diagram, rather than showing a larger image of it, a larger image of the first diagram is displayed.

    Reply
    • admin says

      March 9, 2017 at 9:09 pm

      thanks for pointing it out, it appears to be some kind of glitch, anyway I have enlarged both the images, so it should be fine now….

      Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Categories

  • 3 Phase (4)
  • 8051 Microcontroller (1)
  • Arduino (11)
  • Audio and Amplifier (102)
  • Automation (8)
  • Battery Chargers (64)
  • Bicycle Projects (4)
  • Car and Motorcycle Projects (39)
  • Datasheets (10)
  • DIY Projects (5)
  • Electrical (15)
  • Free Energy (6)
  • Games Projects (2)
  • High Voltage (14)
  • Hobby Projects (30)
  • Household Circuits (2)
  • IC 555 Circuits (5)
  • Ignition Circuits (2)
  • Indicators (50)
  • Infrared (6)
  • Inverter Circuits (29)
  • Lights and Lamps (97)
  • Medical (8)
  • Meter and Tester Circuits (38)
  • Motor Driver (17)
  • New Circuits (56)
  • Oscillators (30)
  • Pets and Pests (5)
  • Power supply (80)
  • Protection Circuits (25)
  • PWM (9)
  • Remote Control (20)
  • Security and Alarm Circuit (48)
  • Sensors and Detectors (66)
  • Signal Processor (23)
  • Solar Controller Circuits (62)
  • SSR (3)
  • Temperature Controller (20)
  • Timer (25)
  • Transformerless (7)
  • Transmitters (12)
  • Tutorials (45)
  • UPS (2)
  • Voltage Regulators (57)
  • Water Sensor and Controller (29)
  • Home
  • Privacy Policy
  • Contact
  • Disclaimer
  • Copyright

© 2025 · Making Easy Circuits