Below is a link to a YouTube page by "All Things Bobot".  It details how to construct a train speedometer including the Arduino and Gerber files to print a housing for the speedometer.

https://youtu.be/RSsRMSD27-I?si=8zAZA74sxkwoh1p3

I built a display using Bobot's files and it works and looks great on my board.

Hope this helps,

Tom

I don't see the Gerber files for the board or the 3D file for the display housing, where did he hide that?

The following link describes a project to control the speed of a conventional train.

https://ogrforum.com/topic/spe...-conventional-trains

The first part of the project describes a speed sensor car that measures the speed of a train anywhere on the track and transmits the information via blue tooth to a base unit. This speed information is then used to control the track voltage to maintain a constant speed.

For testing the train speed was displayed on the Arduino video display. A different base unit could be built to display the speed of the train from anywhere on the layout.

John,

Yes, original poster deleted the Gerbers & 3D files.

Didn't catch that when I posted the YouTube link.

Here are the files I originally downloaded from the Blog.

Tom

Did you happen to get a Bill of Materials for stuff like the display?  I can't find anything like that on Adafruit.

@gunrunnerjohn

@Bobot

John,

Hope this helps.

Tom

Screen:  https://amzn.to/2OubMmj

From Bobot:

@AllThingsBobot

6 years ago (edited)

Pretty much as written on the board and seen in the photos: Arduino Nano v3, (2) 150-ohm ¼-watt resistors, (2) 100K-ohm ¼-watt resistors, a 47uF electrolytic capacitor, a surface mount DC power barrel jack, an 8-pin and 4-pin header, and this LED display https://amzn.to/2OubMmj Solder/wire it up, load the Arduino sketch found here: https://allthingsbobot.com/model-railroading/model-railroad-speedo-part1/ and cross fingers and pray.

Supplemental Info for Model Railroad Speedometer – Part 2 →

@AllThingsBobot

4 years ago

IR sensors: https://amzn.to/36RQRQA Yeah, the billboard was a cool project to design and print. Thanks for watching!

Bummer, the sensors are out of stock.  However, I've seen similar things, I'll look for those.  I suppose I can also 3D print a holder and just buy the photo-transistor and emitters as well.

@gunrunnerjohn

I used these IR sensors for my build.

If using the above IR Sensor, modify the PCB by removing these two resistors and shunting with a wire.

John, I know you already figured this out, including for others who may be not as qualified and following this thread 😁

Tom

@TomNe posted:

@gunrunnerjohn

I used these IR sensors for my build.

I actually found the ones he specified, turns out after searching the number that they are a common part.  I knew I could use something else, but I figured why reinvent the wheel if it was already working.  The question of speed comes up enough that I thought this would be a fun little accessory to have.

@gunrunnerjohn

John,

Short video of the speedometer on my layout.  Easy build with the pcb and the 3D printed billboard for the readout screen The Arduino code worked flawlessly and will allow for a speed reading for travel in ether direction.

Looks great Tom, thanks for pointing this out.

I just have to see who's the cheapest to get some PCB's made.  OSHPark is kinda' expensive for larger boards, I'm going to see if SEEED Studio is cheaper, sometimes they have a good deal.

Got ten boards from SEEED Studio, so if anyone is looking at this topic and wants to duplicate it, contact me for the board.  I'll only need one, but the order increment was ten.  However, it was cheaper per board than OSHPark, so I pulled the trigger.

Wow!

I asked a question that has generated much interest and I've learned so much. So far the advice has been great and has got me thinking in different directions, especially providing the ability to monitor continuous speed readouts. Magnets on a wheel, I'd never thought of that.

Thanks to Tom's link and advice and a couple of days ago Bobot replied with the info I sort of remember seeing a while back. That concept and coding is what I need for now. Wish I had a 3D printer and his multiple skills. I do have a friend that is excited about helping me though.

With Gunrunnerjohn's ideas of parts available, I've got a running start.

So, "Katy bar the doors!

Thank You all

Bob

Step #1 is finished.  I ordered the display and fired off a print for the 3D parts overnight.  They came out just fine.  I may reprint the support base for the display with finer layers, it has more lines than I like.  Of course, it does pass the 2-foot rule, looks great from two feet away.

I already have the Arduino Nano boards, so I just have to wait for the PCB's and sensors to come in and I can stick this thing together.

This is cool and I wouldn't mind having one myself.  The only disadvantage is that it only measures speed at one point in time, in one place.

Many years ago a company called Kansas Junction made and sold a kit, including a custom circuit, to build a "speedometer car."  You had to supply your own boxcar.  The kit included a circuit board with an LCD display and an IC mounted on it.  You had to add a wooden dowel to the car axle, and wrap it with a tach tape (supplied), so that an optical reader could count black-and-white stripes through a hole you made in the car's chassis.  You also had to make a mount for the display out of styrene.  The whole thing was powered by a 9V battery mounted inside the car.

It works great, although battery life isn't great, and from some angles the LCD can be a little hard to read.  Obviously you can't view it when the train is in a tunnel, etc.!  The cardinal advantage of putting the speedometer in a train car, is that it lets you measure the train's speed all the way around the loop and note the degree of variation, for example when the train transitions from straight to curved track or encounters a grade, etc.  I don't know how many were made, but these Kansas Junction kits are now very hard to find.

If you're only interested in performance testing, there's a more common and perhaps easier-to-use alternative: a Lionel steam RailSounds 1.0 box car!  These use a Hall-effect sensor to measure track speed.  Every time the speed drops below about 6 mph, the synchronized "chuff" changes to a hiss and release of air.  If a train can get around a loop repeating the air release sound and NOT chuffing, that would represent an outstanding performance!  But if it's chuffing along slowly, and then abruptly changes to the steam release sound when it enters a curve, then the motor/gearing isn't making enough torque to maintain speed in the face of the increased friction.  (Note:  All of the testing I did with this setup was in the mid-to-late 1990s, on tight tinplate curves and before the advent of speed control.  Only a few of the many locos I tested were able to get all the way around my loop at less than 6 mph.  Fun times!)

I personally think it's going to be a cool addition.  It's as much for the fun of having it pop up the speed of the passing train as it is actually doing performance testing. Of course, since virtually all my stuff has cruise control, I'm not all that worked up about measuring speed continuously.  My speed variations are very small all around, including grades and curves.

As far as the speed sensing car, it would have been trivial to add a track power option, I don't know why you'd feel stuck with batteries.

Gunrunnerjohn, I'm not familiar with how to add a track power option to the cars. Can I retrofit a flatbed or other car with collectors so I can power an Arduino and other electronics? Parts available?

I want to pursue the continuous speed monitoring path and don't want to use batteries.

I like what you've done to mount the display. No 3D printer but I am a woodworker and plan to make the sign with some nice wood. Also plan to make my own tunnel entrance surrounds from some nice wood.

I got the following error when I compiled the sketch:

C:\Users\The Jacksons\Documents\Arduino\O_Scale_Speedometer\O_Scale_Speedometer.ino:23:10: fatal error: Adafruit_LEDBackpack.h: No such file or directory
#include "Adafruit_LEDBackpack.h"
^~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
exit status 1

Compilation error: Adafruit_LEDBackpack.h: No such file or directory

Wish I could help Scott. But, that is what my buddy handles. (When he's available..)

When it comes to programming, Guess I'm not very useful.

I'll be glad to share what we've done after we get the rest of the programming done and the bugs worked out. We'll likely use the referenced Arduino program with stationary photo eyes first then go for the dynamic speed monitoring after.

@Scott Jackson

You need to add: Adafruit_LEDBackpack library to the Adrino program.

Tom

Tom, any other libraries we need?

@gunrunnerjohn

John,

Three libraries are needed:

Wire

Adafruit_LEDBackpack

Adafruit_GFX

Tom

@TomNe posted:

Three libraries are needed:

Wire

What is this one?  I found a bare wire.h, but no library.

@gunrunnerjohn

John,

You may already have this library loaded in your Arduino IDE program.  It is a common library used for control IC2 device interfaces.

Wire

I found it in several projects I have, so apparently you just add it with an include.  I downloaded the latest copy, problem solved.   I have to bang the cobwebs  out of my Arduino knowledge, it's been quite a while since I used the Arduino, I've been using the Microchip PIC for projects as I needed it to be really small.

@TomNe  Thanks, that did it