DIY Arduino Model Railroad Reversing Loop 

Ok everyone! The link I had was private. I set it to public. The project link should work now!

I am from South Africa and am busy building a track for my kids (8, 6, 4). Your stuff is FLIPPEN COOL! Thank you :)

Hey everyone! Thanks to @David Mead. He caught a typo at 11:06. The pinMode should be sensor2

Jimmy; Great info and video. And especially for hanging the N.Y.C. 20th Century Limited. poster. From 1915 to 1967 my Great-Uncle John Lynch was one of the three longest tenured Loco Engineers on the 4-8-4 Hudson & 4-8-4 Streamlined Hudson (J-1 Class & J-3a Class). In memory of his years "ON THE LINE" it is also one of the HO Scale HardBodies I run on my home layout. Thanks; Jim

Thx for this awesome video !!! You helped me alot with my reversing loop setup. Keep up the good work you're doing a great job !!!

Happy New Year Jimmy ,thank you ,im glad you are continuing the Arduino tutorials, cant wait for the next ,take care for now.Mac

Thanks for sharing your thoughts and information. You have me considering using a Ardurino on my MRR Design(s) after more thought.

Nice tutorial Jimmy, I'm building a N scale track as well and document every step. I do not have DCC but de regular Analog DC version. However I learned already a lot from your videos in controlling the trains. I have a long way to go but getting there.

At 3:40 the for dependability and safety the wiring of the relay contacts should be reversed with the power feed going to the outside terminals and the track connected to the inside terminals. As shown, if one relay drops an instant before the other a dead short is created as both power lines will be connected to a single rail. When the wiring is reversed under the same conditions both rails will be connected to a single supply side; a much less destructive situation.

Fantastic i heff made a reversing loop like you and it works perfect and beter dan al athor systems THANKS !! HC Treintje Belgium.

Hello Jimmy, first of all I wish you and your family a Happy New Year and for me many videos from you :). Nice video but is it possible in the future to have a zoomed in pic of your accessories and connections? Just for understanding! Thx.

Hello Jimmy, had question but did some study on the motor shield and solved my question on how to connect a tortoise switch machine so problem solved. Waiting on your next video and thank you!

I'm so in..Altho I'm still in the Steam-age, I'm learning that's to teacher like yourself Jimmy,love these ardunio tutorials

liked your approach to the revers loop. Have built and n using the DCC EX command station. I have two reversing loops on my layout. The question , do I have to link the reversing loop (Arduino system )to the command station or can it function on its own with sensors controlling the turn outs and phase change

Hey Everyone! There is now a Github link with bug fixes for the code! Check the description!

another good tutorial Thanks alot Jimmy all the best for 2020

Thanks for the video. I’m starting my n scale layout and was worried about reverse modules depending on a shortcut detection. This is great! Just one question: I’m planning to use android controlled servos for my turnouts. How would you make them talk to this great module?

Seems there is a major bug in the sketch, the values being passed to the functions "switchXX" are sensor1, sensor2, which is essentially the Analog pin nos. that the IR sensors are connected to, instead the readings of the analog pins A2,A3 should be passed. The analogRead(sensor1) should be changed to int sensor1Val = analogRead(sensor1); sensor2Val = analogRead(sensor2);, which should then be passed such as switchR1(sensor1Val,sensor2Val); and so on...

Jimmy, nice idea and good to see. I was thinking about something similar, needing more effort on HW side. I guess I think about that again. It can obviously be done with less. Looking at the code in the video and on the google drive though: Analog inputs can also be used as digital inputs. So a digitalRead() will work as well. In the loop() you read both sensors (line 30 and 31) but you assign them never to a variable. So the Serial.print() should always print the pin numbers of A2 and A3 - I believe - "15" and "16" to the serial monitor. I assume you want to set the power of to the motor shield via PWM. That would be a analogWrite(), not digitalWrite() in the switchxx() functions. I assume the digitalWrite(power, 255) is somehow understood as a digitalWrite(power, 1) by the compiler. Additionally, the switch functions will always be called with pin number for the sensor pins (see above) and those are always less than 200. And with that the code should just loop through the sates about every two seconds. But your video shows clearly that the loop works. Do you have updated code for us? Or am I just missing something?

I think I see one flaw in this system. If the track switch for some reason flipped unexpectedly, or was manually switched, then the system would short out. This concept relies heavily on the track always being in the right position for the train entering. It is a nice video, but personally, I would not use this system. The short-circuit detection method is more reliable. Also, since my own track has multiple exits within the reverse loops, the train does not always exit back on to the track it came from. Therefore, the next train entering the reverse loop would be in for a shock (literally). Again, nice video. My criticism is meant to be constructive. I'm not attacking your ideas.

Like the build but how long can the wires be. Also will this work with the DCC Command station and the DCC EX motored shield

Hello Jimmy, again another great video and being one that is very new to arduino and understanding them and the language is a huge problem for me so may I ask how do you connect a tortoise switch machine to this?

I’m in trouble! My kitchen aid mixer has a dough hook but no bread board! When two hobbies.... baking and trains collide.... 😆

exactly what i was looking for, thanks!

A very interesting and useful video . Thank you for sharing your expertise

Great video, but I not sure what the bumping music in the background adds to it, just a distraction you my mind.

Thats a nice solution. I will try it with my layout.

Very smooth and informative

Question. Can I run both ends of the loop like this with one arduino, two sets of sensors and 2 relay boards? Thanks in advance for the help.

Jimmy is there a way of using a servo instead of using kato switch like you use with the same setup

Great video. Can you achieve the by using current sensors instead of ir?

I have a complicated track plan that o would love to do and it has two reversing loops I believe. Would it be possible to show you the plan and help me work out what I would need to put and is it even possible. This would be my first ardurino project and if like to use it so the turnout controlled polarity that controls signals again if possible.

This is another great video but I am having some trouble understanding what the different pin variables are for. There is no overview that really explains what these are for. I can see in the final sketch what the code does but I am having trouble mapping that back to what is happening on the layout. The variable names are somewhat descriptive but the effect of turning some high and others low isn't clear to me. After watching to the end I could (sort of) figure out what the purpose of the loopState variable was but the rest is not even that clear. BTW, I am a software engineer with 35+ years of experience (beginning with C). I am just now starting my exploration of Arduino and really loving it. @diyandigitalrailroad I could recommend a few things to make your listings a bit easier to follow if you like. Nothing major, though. I like your presentations, overall.

Is it possible to add the line diagram of all the connections?

Is it possible to make a dc reversing loop

Hi Jimmy, Love the video but I am still having trouble with the arduino sketch, I'm getting a message that switch R2 was not declared in this scope in the second phrase of the primary void loop. I assumed it was a syntax error but I cannot find any inconsistency with your original. Is it possible I missed an edit, or there was something not on the video? I'm a Linux novice and still learning definitions. Also I did not have a dual relay handy and am trying to use two single relays. Will this require any change to the code? Thanks again for your help.

Is there an automatic reversing loop for dc trains?

surely there's an easier way to do this by now?

Happy New Year indeed. I'm loving this Arduino stuff but I have a question. Can track polarity reversal (not interested in the turnout driver portion) be done using short circuit detection rather than the optical sensors? That is what I'd like to see. Sadly I'm not tech savvy enough to puzzle it out on my own so please keep it simple.

I'm late in watching this. Missing is the explanation of the logic of what this is doing. Break? I assume "break" is some obscure motor shield command? This seems more expensive and complex than the commercial auto reversers. What are you using for a switch machine?

Is there a typo in your sketch? In your PinMode things shouldn't the last one be sensor2? To me it makes no sense to declare the same thing twice.

Do you know if this can be done with dc and not dcc?

Great tutorial but I ended up switching it off after a few minutes as that background music is so annoying and you can’t turn the volume down or you miss the commentary.

OK I guess I'm just having a dense day but I finally after static test was trying it on my actual railroad reversing loop. Everything seems to be OK but for the life of me I can't seem to figure out where the red and black wires from my Kato switch machine should connect. The diagram seems to say out1 and out 2 on motor shield but that doesn't exist as labeled?

hello again, have you had the opportunity to resolve the problem with either the code or the setup?

Nice video Jimmy! One question... Where were the insulated frogplates? Each end of the turnout, or just at the split end?

I cannot find the sketch for this anywhere. The link given no longer works. Can you provide a link I can use?

Hello, I have been working with this project of and on now for as cooker of weeks. I have everything hooked you exactly as you, same parts, your sketch and I'm just trying to get the static test to work. I haven't made it to hooking up the shield and track yet. I get blinking lights on my relays and continuous 16 and 17 in serial monitor. Appreciate any help. Thanks.

I'd really like to see how you can incorporate the infrared sensors into a layout where they are hidden from sight. I'm really interested in a lot of the work you do but struggle to think how it's possible to conceal it and have it functional.

Will a L293d motor shield work?

Hello when the polarity from the main track is reverse while the train pass in front of the second sensor will it not affect all the rest of the Dcc accessory and other locks?

would be nice if there was a text file for sketch really like this approach over frog juicer as turnouts are also controlled

Hello, sorry for my bad language, I'm from France. Can I use this for a turntable. One sensor on the main track and the other sensor under the track of the bridge and connect all the track after the turntable to the main track. Thank you for your help.

Can this be done on O gauge?

Can you make the cross-signal (arduino+ led + servo + DFplayer + IR or ultrasound sensor) for your next episode?

may I ask how do you connect a tortoise switch machine to this?

you should not touch the carpet with your boards , static electricity can sort them out.

Can't you use a relay instead of a motor shield to fire the turnout motor? A single DPDT relay to handle the "polarity" (or two SPDT in tandem), With one SPDT Relay to provide "power" on the hot lead. Your sensor setup stays the same. Timing: sensor read (1 or 2) set next switch state (determines the state of the DPDT "Polarity" relay), when the second sensor is reached, the Arduino momentarily pulses the power relay to fire the switch motor then returns to the power off state. Power for the turnout is provided separate (isolated) from the Arduino to avoid any possible spike. This setup would also work on duel coil "Snap-Switch" turnout motors with slight modification... the "Polarity" relay would need only one set of contacts, 1) to set switch to normal and 2) to set switch for diversion. I am new to Arduino programming but see this as a way to minimize motor shields that take up multiple pins to control.

Hi, where the avoidance control is connected

hello, not sure if anyone else is having this problem, my setup, not connected to track but to a kato switch, seems to be in a constant loop. the switch will switch back and forth continuously every second, the ir sensors react but nothing will stop the relay from switching back and forth. the serial monitor shows a value of 16 and 17 respectively from the two sensors. have tried with different arduino uno and different sensors and motor shields. the sensors will output zero volts and then to 5 volts when activated, but the relay continues to switch back and forth. again the serial monitor shows no value change either. thanks in advance for any direction, charly

Has anyone ever gotten this sketch to work? Jimmy keeps saying he'll post the updated code, but he never does. Makes ya' kind of wander...

ok was this a great video as everyone has mentioned? has anyone else had the problem with the setup or the code as i have? i have asked for help being the newbie i am and have received none, not even from the peanut gallery. great ideas but maybe there is more help elsewhere.

The music is annoying and distracting. 👿

Would this work for strait DC as well?