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Stepper motor for model railroad turntable

Posted: Sat Dec 05, 2009 9:28 pm
by cm2033
Wow!! What a great place to find.
I am new to this so I hope you will bear with me.
I am looking to control a small stepper motor for use on a model railroad.
A turntable to be exact. It needs to rotate 360 degrees. I need to be able to program it so I can have it stop at selected places. Would like to have the motor start out slow and accelerate to about 1 RPM . Then when the slected is aproched it will deaccelerate to stop. Would like it to be a stand alone idem- no coumpter needed to program. (not sure this can be done)
There are many low cost stepper motors on the market, but finding a controler to control it can be $$.
BTW I have read some of the stepper motor control projects.
Thanks in advance.

Posted: Tue Dec 29, 2009 7:46 am
by ThePyroElectro
Aside from building your own which might take more learning than you desire. You can get stepper motor controllers for cheap and easy interfacing from a lot of online hobby stores.

Easy Stepper is one of the neat modules that is pretty easy to use.

Re: Stepper motor for model railroad turntable

Posted: Fri May 21, 2010 3:24 pm
by sierrasmith71
cm2033 wrote:Wow!! What a great place to find.
I am new to this so I hope you will bear with me.
I am looking to control a small stepper motor for use on a model railroad.
A turntable to be exact. It needs to rotate 360 degrees. I need to be able to program it so I can have it stop at selected places. Would like to have the motor start out slow and accelerate to about 1 RPM . Then when the slected is aproched it will deaccelerate to stop. Would like it to be a stand alone idem- no coumpter needed to program. (not sure this can be done)
There are many low cost stepper motors on the market, but finding a controler to control it can be $$.
BTW I have read some of the stepper motor control projects.
Thanks in advance.


Hi!


I have "almost" finished a project that does what you are looking for. I have gone through a number of interations and design changes and am close to wrapping it up.

I used the PIXAxe 28X2 microcontroller, a motor driver L293D, a 4 x 20 LCD display and a Anaheim stepper with a 51 to 1 gearhead. -(1/2 rpm rotation speed, with acceleration and decel...looks very protypical) There is correction programmed in for the gearhead backlash (about 3 degrees) that is applied if a new move is in the opposite direction from the last move. I also have a brake system implemented that (using a RC servo) that hold the turntable in position - so it does not move within the backlash span.
Once programmed (I used PICaxe Basic) It is a stand alone unit and does not need a PC.

Up to 32 tracks can be selected,and you can move end A or B to any track that has been activated. e.g. to turn an engine , select current track location and select end B, enter with the pushbutton...it will move end B to the current location and you engine is now turned!. Use of the control is largely menu driven on the LCD display , with selections made with a rotary encoder and a push button.

I use a micro ATX power supply ($18.00 delivered) for the +5 logic power and +12v for the stepper motor. I used this supply because it has a "power good" output that goes low about a mS before power is lost. I use this to call an interupt the saves the current turntable position in the controller's EEprom. This prevent having to re-index the truntable if power fails during a move (it has to know where it is so it can move to the selected track) .

Lots of fun, lots of learning and some gnashing of teeth. This was my first programming adventure since I wrote some assembly language code programs in 1976!


David G.
Maryland USA

Re: Stepper motor for model railroad turntable

Posted: Thu May 09, 2013 12:42 pm
by ChrisPSR
David,

I know it is some considerable time since you wrote this description of your stepper motor controller which is through a PICaxe microcontrolled circuit for a model rail turntable but is there any chance of receiving the program in Picaxe Basic please and a circuit diagram?

Cheers, from across the pond,
Chris Spreckley,
Manchester, UK.

Re: Stepper motor for model railroad turntable

Posted: Thu May 09, 2013 2:42 pm
by sierrasmith71
Chris....

My, time does fly!!

"I have "almost" finished a project that does what you are looking for. I have gone through a number of interations and design changes and am close to wrapping it up. "

Well I never did finish the project as life, and other programming interests, got in the way.. I turned my attention to touch input control of servos for contolling turnouts. I did finish that project and I used the Arduino Controllers for that and wrote all the code in C++...

All the code I wrote for the picAxe is now lost when the PC I was using crashed and burned ,,, a total loss and I did not back up! --another lesson learned.

I did eventually create a DCC motor drive for a turntable. I used a large RC Servo motor with the guts removed--just the motor remains-- and a DCC loco controller to operate the turntable. I assigned a loco address and use the DCC hand controller to move the turntable to the posiiton I want...It is non indexed amd fussy--watch the speed and overshoot, , but since I model in On30 in the 1940s and the turn table was hand powered it is very prototypical..


I see that Walthers now has a stepper motor driven indexing HO turntable for a few hundred Dollars!!


Best regards

David G.

Re: Stepper motor for model railroad turntable

Posted: Thu Mar 17, 2016 7:14 pm
by hnoor0044
I used this supply because it has a "power good" output that goes low about a mS before power is lost. I use this to call an interupt the saves the current turntable position in the controller's EEprom. 



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