Model Railroad Project Guidance and External Power Source Questions

Using Arduino Project Guidance
1

Hello!

I am creating a small DC n-scale model railroad diorama which will have two independently controlled locomotives that will receive power from the tracks. This is my first Arduino / electronics project so I am pretty inexperienced. I am hoping to get general feedback on my hardware approach, and I have several questions about using external power sources.

I will be using an UNO R3 with the Arduino Motor Shield. I plan to connect a 12V power supply to the motor shield and cut the Vin jumper so the power supply is dedicated solely to the motors. My track will consist of multiple electrically isolated blocks to enable the two locomotives to run simultaneously. I plan to use a 5V DPDT relay board (Data Sheet) to switch the track power source between the "Motor A" and "Motor B" output from the motor shield.

I will also have TowerPro SG92 servos for operating turnouts, and anticipate incorporating other components such as IR sensors, decorative LEDs, and a 7-segment display at some point. I am planning to power the Arduino, relay board, servos, and other components with one 5V power supply. Below is a conceptual diagram:

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My specific questions are:

  1. Is there any risk to the Arduino with this set up? Or is this fine since I'm not powering anything through the Arduino?

  2. Is there potential for interference between the different components using the 5V power supply? For example, if all the relay coils are active, will the performance of the servos be impacted?

  3. Would using something like this 12V/5V power supply be appropriate if I want to only have one cord to plug in to the wall?

  4. Would it be possible to power everything using just the 12V power supply and a 12V to 5V buck converter, assuming it can provide enough current? Could this affect the operation of the locomotives or expose the Arduino to potential interference?

Thank you!

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I can not really answer the questions; I think that the design is OK. Be aware that you can not power the Arduino with 5V as shown and at the same time use USB.

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3

It looks OK but I would set the buck converter to about 8 volts and power via Vin, you will get additional filtering from the onboard power supply. This could prove to be very important as your train engines have motors that generate lots of electrical noise. You can get a 12V relay board and operate directly from the power supply removing that nasty load from the Arduino. The 12V board will work , it has the same interface input interface, only the relay coil voltage is different. I have actually replaced relays to change a board, no problems.

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