A couple of years ago I came up with a way to control 4 turnouts using an Arduino Nano to control the turnouts on the small switching layout I was building when I worked on the road. I figured out that I could control 4 turnouts with one Arduino Nano using 1 push button for throwing the turnout and 2 LED's to indicate the turnout direction. If you are interested here is my YouTube video showing the prototype.
https://www.youtube.com/watch?v=7sN1HnTmX8U&pp=0gcJCUEMAYcqIYzv
Once I had it all figured out I made PC boards for this.
Now comes the "However" ;D On my recently built staging yard some of the turnouts are too close to the benchwork to under mount the servos so I needed an above mount system to remotely throw the turnouts. A few months ago while at an ON30 meet a fellow member (who likes to pick my brain with anything to do with Arduino's) gave me a small motor with a gearbox and asked me if I thought if they could be used to control a turnout. I said "I don't see why not" and said I would look into it when I has some free time. Well the time is now.
PlanetaryStepperMotor001.jpg
Here are the two types of the planetary stepper motors with built in gearbox and linear screw I picked up from Aliexpress. They are also available on Amazon and other places.
The goal is to use them to control the turnouts on my staging yard using a push button to control them and LED's to indicate direction, just like I did on my servo project.
Will I'm still in the design process I thought I would start now so you can see my trials and tribulations.
Next up, did I bite off more that I can chew? :o
Thanks for looking in.
Could you shoot a little video showing how those work? It's not quite clear to me what actually gets moved by the motor, particularly on the right side unit.
dave
Ron, thanks for starting this thread.
I'm sure you'll be able to figure out how to get them to work.
Those look like the drives used on disk drives to position the reading head or laser on an optical disk drive.
Bernd
Quote from: deemery on November 09, 2026, 08:13:17 AMCould you shoot a little video showing how those work? It's not quite clear to me what actually gets moved by the motor, particularly on the right side unit.
dave
Dave,
I can shoot a short video on how they work, I need to move them to the center anyway, give me a couple of days. ;D
Quote from: Rick on November 09, 2026, 08:25:37 AMRon, thanks for starting this thread.
I'm sure you'll be able to figure out how to get them to work.
Thanks Rick, I think I have it figured out, just need to test it. ;D
Quote from: Bernd on November 09, 2026, 08:54:39 AMThose look like the drives used on disk drives to position the reading head or laser on an optical disk drive.
Bernd
Bernd, they are Kind of. The ones used in disk drives usually have a longer screw
images.jpg
Planetary stepper motors useful for this application usually consists of 3 parts
1 – stepper motor
2 – gearbox (the planetary part)
3 – linear screw
Most planetary stepper motors are bipolar and require some sort of motor drivers to organize the phases so that it can move clockwise or counterclockwise. Some suitable motor drivers are as follows.
· ULN2003 driver board
· A4988
· DRV8833
· L298N Dual Chanel H bridge
· SN754410NE
There are others that can be used.
Bipolar stepper motors work by passing current through 2 coil windings (phase A and phase B) and actively reversing the polarity (direction) to turn a magnetized rotor in precise incremental steps. Because of this there are 4 wires, 2 for each phase normally shown as A+, A-, B+ and B-. Because there is no center tap the driver is required to push and pull the electrical current in opposite directions through its windings to rotate (this is probably more that you wanted/needed to know).
I spent a lot of time trying to figure out how to home the stepper motors. At first I thought that because the screw limits the movements in either direction that there should be a way to home the motor without any additional items required. I suppose there is by using the torque of the motor, but I have a feeling that will burn out the motor. After some research I decided to treat this like any other stepper motor and will use a limit switch to home the motor.
The goal of this exercise is to control turnouts using a planetary stepper motor controlled by a pushbutton and use 2 LEDs to indicate direction. My plan, like my servo motor project, is to use components that can be used on a PCB board. This is to make everything neat and to save space.
So what will be needed for this project?
1 – Planetary Stepper Motor (to drive the turnout)
1 – Arduino Nano (provides processing power)
1 – SN754410NE motor driver (this is an IC that will be mounted on a PCB board)
1 – Limit switch (normally open – used to home the stepper motor)
1 – Pushbutton (normally open – used to operate the stepper motor)
2 – LEDs (1 green and 1 red to indicate turnout direction)
Next up – Wiring diagrams
Thanks for looking in.
Ron, that was a great post explaining how these particular steppers work, and what you need to control them. Thanks!
dave