Project using 50 small stepper motors

Hello all,
I am brand new on this forum and pretty newbie in general with arduino. I am very inexperienced with electronic hardware so I was hoping for any guidance on this project.

I want to control 50 of these small step motors:

I'd like to control them individually and simultaneously (or close to it). They don't have to spin extremely fast, but definitely a decent amount (it's for an installation, so not practical usage or much resistance put on them).
I additionally would like to use a number of photo cells too, I'm not sure how many but let's say around 10-30 depending on what's needed to work these motors.

So I am wondering how I can do this with an Arduino Mega: how many Arduino Megas would I need to purchase? Would I need to buy drivers or some kind of controllers? Any recommendations for what I would need as for power supply? Any kind of hardware that would be useful or that I need?

I believe I need a transistor for each motor, correct? I was thinking of buying these:

Yes I am very new and clueless about these larger scale projects, any advice would be greatly appreciated! And yes my budget is very tight, haha.

Just curious, what project are you creating with 30 photo cells and 50 stepper motors?

those motors are not steppers. you only need an h-bridge to run forward and reverse, or just a FET like a 2N7000 to control them.
you will need 50 outputs and 30 inputs. plus some extra for LED's and switches and such.

Thanks for the responses!
I see, good to know they are not steppers. So do my outputs have to be PWM or can I use other digital/analog outs? How many Arduino Mega do you think I would need to accomplish this (forgetting about the photo cells)?

The project will just be a surface with the 50 motors spinning those little propellors (installation art). We aren't sure yet, but probably will use the 10-30 photo cells to affect which motors are running.

Take a look at this link. Provides a good explanation about using an H bridge to control a DC motor. If you want to control speed, yes, you will need PWM pins, but you will also need 2 other pins (one per direction). If you have 50 motors, and that's 25 h bridges, and 150 Arduino pins.

edit: You could potentially cut down on pins if you would want multiple motors being synchonized

Not to mention, another 10-30 for the photo cells.

Oh, here is a link regarding reading photo cells and using PWM pins.

Thank you so much for this help!!

So I need 3 pins per motor, the additional 2 for each direction. Do all 3 of those pins need to be PWM? If not what pins can I use for the other two?

at 20,000 RPM, it will be hard to know they are spinning, they will be a blurr.

pwm can be in software or hardware, really depends on the effect you want.
each MEGA has 15 or 16 hardware PWM outputs.

I would offer that if you get one and try to spin 50 of them with SOFTWARE PWM , and it works, then you need two. for the pwm and one for everything else, or half and half.

do you plan to spin in both directions, forward and reverse ?

if you do, then you need an h-bridge per motor, that is eitehr 50 h-bridges, or 25 dual h-bridges.

No I just need to spin forward at varying speeds. Can I just use an FET then? If I use an FET how many PWM pins do I need to use per motor?

Thank you thank you thank you!!

ndivuyo:
No I just need to spin forward at varying speeds. Can I just use an FET then? If I use an FET how many PWM pins do I need to use per motor?

Thank you thank you thank you!!

one pin per motor. teh FET is like a swith. turn it on and off , mostly on, partially off and it spins pretty fast. mostly off and partly on and it spins pretty slow. all the way on, full speed, completely off it is stopped.

Awesome!!! Thank you. So I guess I will use 4-5 arduino Mega then.

One last question, is this an FET transistor by any chance? https://www.amazon.com/10PCS-TIP120--220-Darlington-Transistors/dp/B00UPB25PC/ref=sr_1_1?ie=UTF8&qid=1468299393&sr=8-1&keywords=tip120+transistor

Otherwise I will look up the 2N7000 or something similar.

You guys helped me so much, I really appreciate it.

do you have any arduino now ?

you would need some resistors, say, 4.7 k from the Arduino to the FET and say, 47k to ground.

pretty easy to get started.

I have arduino mega and uno.
I am planning to order these 50 motors, transistors, and the other 3 or 4 Arduino Mega today, but don't have any of the motors to test! Unfortunately I only have a couple weeks to wrap this project up, so I can only do one big order! Definitely plan on getting resistors, thanks for the tip :slight_smile:

Oh an is that transistor I linked an FET transistor that will work for this?

Thank you again

ndivuyo:
Awesome!!! Thank you. So I guess I will use 4-5 arduino Mega then.

One last question, is this an FET transistor by any chance? https://www.amazon.com/10PCS-TIP120--220-Darlington-Transistors/dp/B00UPB25PC/ref=sr_1_1?ie=UTF8&qid=1468299393&sr=8-1&keywords=tip120+transistor

Otherwise I will look up the 2N7000 or something similar.

You guys helped me so much, I really appreciate it.

no. those are huge
what is needed is a data sheet for your motors it looks like they are rated at 1.6 amp plasma current
have to admit I have no idea what that means as regards yoru motors.
but you should have a FET, not a transistor. the transistor could be used, but will consume more power and require a largter and higher voltage power supply.

I see I see, Ok then I will order the 2N7000's like you suggested. Thanks!

before you make your big order- what do you plan to use to power everything?

if you are in a hurry, and you want to use the TIP120, you need to get different resistor sizes.
without the data sheet, we do not know the motor resistance, so we do not know the power so cannot calculate the transistor.

I would offer that 1k resistors would either handle the load, or you could double them to get 50 ohm and that would handle the load.

Hey, actually I cannot order those motors because they will get here in August!
I plan to order these now:

Could I still use those 2N7000s and similar resistors? Something tells me I need a different setup :confused:

I am not sure what to power everything with yet. Any suggestions? Whatever is the cheapest route I guess haha.

Thanks all!

This board + 16x 2N7000 + 16x 1N4004 can control/PWM 16 DC motors.
And use only TWO pins (I2C) of the Arduino.

The same board can also drive 16 servos, without additional hardware (just plug them in).
Or PWM 16 LEDs, or 16 constant current (power) LED drivers.

Three more boards/transistors/diodes, and you can control 64 motors.
With the same two Arduino pins.
The limit is 60 boards (with two Arduino pins).

Example here.

Leo..

Wow wawa so are you saying I could control the 50 step motors with 1 arduino mega?
I would get 5 of these drivers and use only 5 PWM pins from the arduino correct?
And then supply an individual power source for each of the drivers?

Would this work for these 2 phase, 4 wire stepper motors?

What else would I need for this? Those same FET or some other transistor? I suppose the around the same readings of resistors (4.7k and 47k)?

Thank you for showing me this!