Help with Stepper Motors

Hi
I would like to build something like this.
Would this stepper motor be strong enough: Arduino Store

But is this a unipolar or bipolar motor? Also, it says “Rated Voltage 4,2”, is this the operating voltage for the engine? Isn’t it usually around 12V?

I would like to use a circuit like the one on the picture to control it. But im not sure if this circuits for bipolar or unipolar steppers. Is it easier to control a unipolar or bipolar motor?

As you can see I really need some general advice on steppers :slight_smile:

power for steppers is something that many people do not understand. they think that because you can drive it at 24 volts that you should. often they will be the first to say that because the spec for a resistor says it can handle 100 volts, that you should not drive 100 volts into a resistor to light an LED.

APPLICATION drives the selection. your application is a non-contact project so power for the stepper does not need to be high. 5 volts would be overkill for a stepper in your application.

motor speed increases with voltage because the voltage determines how fast the coils can be energized. since you will be moving at slower speeds, you do not need much in the way of either voltage or current.

also, you will find people trying to steer you into a microstepper. again, it is that the application is not understood. a simple H-Bridge would be more than sufficient for your application.

the L298 has current limiting pins, so it could easily work with your motor at low voltage (or high voltage) and be set to the power you need. the Data sheet lists these as current sensing A and current sensing B

on the other hand, for the same money, a microstepper from e-bay will be about the same cost.

the benefit of a stepper chip that is designed for a stepper is that you only need two pins. a step and direction. the dual h-bridge will use 4 per motor.

and in your case, if you move only one axis at a time, you can share the direction pin. needing only 3 for the project. not sure if you can connect two pins, one to step on one motor and dir on the other and vice versa.

a note about power. just because you can run 2 amps into a stepper, if the application does not need that, then it is all wasted power.

since steppers lose power as they increase in speed, one way to determine power requirements is to increase speed under load until you loose steps. then back off speed or increase power.

here is a very rough overview of steppers. being geared to the newbie, it skips over some of the technical stuff in favor of simplicity and favors the A4988 as the only proper stepper driver. but it seems to be a work in progress. in the final form, I hope is addresses the L298 correctly and includes the popular EasyDriver.

dave-in-nj:
favors the A4988 as the only proper stepper driver.

Thank you for referring the OP to the stepper motor basics Thread.

However, please don't misquote. It says "typical", not "only".

but it seems to be a work in progress. in the final form, I hope it addresses the L298 correctly and includes the popular EasyDriver.

I don't plan to cover the L298. I believe it is best to steer newcomers away from them - they are more complex to program, they are electrically inefficient and they don't have in-built microstepping facilities.

And the A4988 is "typical" of the Easydriver, BigEasydriver and Gecko and Leadshine drivers so far as the interface with an Arduino is concerned.

...R

"only proper' was the point.

I think your thread is needed one to help people take the first few steps. My hat is off to you for that !

however, my viewpoint of engineering is that of broader knowledge. many people buy things, then come here to figure out how to use them. the L298 has been around for a long time and there are many machines running with them for years. Admittedly they are long in the tooth but when slow speeds are needed for the application, they should be considered. Anyone who comes here looking for help with that driver because they already have it, should get the help we can offer.

writing a step routine for that in either full or half step is not hard. Not sure if there is a library for that ?

bestanamnetnogonsin:
Would this stepper motor be strong enough: Arduino Store
, it says "Rated Voltage 4,2", is this the operating voltage for the engine? Isn't it usually around 12V?

for a stepper, the manufacture has to set parameters for testing. the 4,2 volts is just a test point.
for peak performance, you would want to power the motor more than 10x the nameplate voltage.

however, just like a Lamborgini, you do not run the motor at full power very often, if you ever do. especially in most of the hobby applications.

if you need about 11 hp to driver a 1970 Cadillac at 55 mph, then, why do you have a 500hp engine ? mostly to get it moving from a stop or to pass a slower vehicle.

the chess board application does not require that you ever use full power, so a lower voltage is actually better.

also, with the belt drive the speed of the motor needs to be slow, to make it microstep would be harder to do than to half or quarter step.

If it were me, I would get the A4988 and then half step with it.
If I needed to do one today, I would use a L298 that I have already.
in the end, no one would know the difference.

dave-in-nj:
many people buy things, then come here to figure out how to use them. the L298 has been around for a long time and there are many machines running with them for years.
....
writing a step routine for that in either full or half step is not hard. Not sure if there is a library for that ?

I fully understand. I am leaving it wide open for you to write the Thread L298 Stepper Tutorial

"only proper' was the point.

I can't see these words side by side in my text. If they are there please let me know where so that I can correct any ambiguity.

...R

I really just want a simple circuit that can drive two steppers. I would like to use an H-bridge simply because it isn’t very complicated and I understand how it works. Also, with an H-bridge you can use the arduino library, which really contains all I need. Ive done some more researching and found this circuit (on the picture) on the Arduino site, it says its for bipolar Motors.
My Questions:
1) Can I use this curcuit with this stepper (will the circuit work if I build it exactly like on the picture?)
2) Can I drive the curcuit and motor with a 9 Volt battery? If no what voltage should I use (what voltage would you use?
3) Am I correct in thinking this motor is bipolar?
4) What is the reason this circuit uses an SN754410NE and not the L298?

bipolar_stepper_four_pins.jpg

for your application, you can use the motor with that driver.

9volt battery will not last very long. maybe enough to play one game if you shut off power unless moving.

this has a 1 amp limit
the L298 is twice that.

most people try to pick the largest and fastest and highest power without understanding the need.

bestanamnetnogonsin:
I really just want a simple circuit that can drive two steppers. I would like to use an H-bridge simply because it isn't very complicated and I understand how it works.

The reason I suggested using stepper motor drivers such as the A4988, BigEasydriver etc is because they are actually simpler to use as they only need a step and direction connection to the Arduino and the code can be much simpler because the hard work of figuring out the order for energizing the coils is done by the driver and not the Arduino.

But, hey, each to his own...

...R

dave-in-nj:
for your application, you can use the motor with that driver.

9volt battery will not last very long. maybe enough to play one game if you shut off power unless moving.

this has a 1 amp limit
the L298 is twice that.

most people try to pick the largest and fastest and highest power without understanding the need.

But it says the engine needs 1.5 Amps per Coil...
So i would have to use the L293 and couldn't use the L293D, as it says the peak Output is 1,2 Amps.

If I would use the L293D I would have to put in extra diodes right?

Sorry about the double post, but I found this Motor on Adafruit and it says it only draws 350 Milliamp, but its got NEMA 17 size so it should be the same as the one from the Arduino site right? What exactly does the 1,5 amp of the other motor actually stand for then? Can I, or can I not use the SN754410NE and a 9v Battery to drive it (if only for a short time)?

The 350 mA is the allowed current in the coils. Have you read the Thread stepper motor basics? It tries to explain about current and voltage among other things.

It is very unlikely that a 9v PP3 type battery will move the motor. It probably can't supply enough current for more than a few seconds. It certainly could not supply 1.5amps for the other motor.

In any case the 350mA motor needs 12v, and preferably more, to work well. But you probably risk over-heating the motor if you use voltages above 12v with an SN75441.

...R

Ok all questions I have are cleared now. Except one. How powerful do you think my motors have to be for the project? I would like to keep current and voltage as low as possible, partly because I feel uncomfortable with for example 24V and partly because Im not sure the Adafruit motor shield (that I decided to use in the end) can't handle currents higher than 2A.

In Short: I would like to know if can use this motor for the project.

putting aside the mis-information. the higher the voltage the more the heat and the greater the wasted energy. and yes, if you tried to run at 12 volts, the wasted heat would burn up that battery in short order.

try running the motor on 5 volts. low heat, good movement, no problems.

not sure how to emphasis APPLICATION.
if I were to ask how to size a resistor for an LED that needs 10ma and I wanted to use a 100 volt power supply because that spec sheet says I was allowed to do, because the resistors are good up to 100 volts, I would have the whole community down on my head.

your application does not require anywhere near an amp nor anything over the nameplate voltage of the motor. in fact, you probably could get away with using 1.5 volts to drive the motors properly. that is once you allow for the driver inefficiencies.

what others are missing is that your APPLICATION requires a PROPER driver. like a simple H-Bridge.

Proper:** 2**.
of the required type; suitable or appropriate.

the key word here is appropriate.

if you were making the whole chess board get up and walk around you might need that 9 volts. if you wanted to do it fast, you would way over volt the motor and pump in 12 volts, but that would not be proper for this application. Then you would be discing the need for a fan to blow away all the heat energy created by the wasted use of too high of a power supply.

You are only moving arms that move a magnet. and even doing that slowly. I cannot imagine trying to run a chess piece at 600 inches per minute only because you have a 12 volt power supply and could not figure on how to get the proper voltage.

and I cannot imagine using a micro stepper to move a chess piece. well, how many zeros of positioning accuracy do you need ? if you feel the need to get past 3 decimal places, then a micro-stepper could help.

Since you can drive any stepper (in the hobby range) on 1.5 volt batteries, you can try it out for yourself on your bench.

set up a bunch of switches to simulate an h-bridge, connect a simple D cell and then push the switches in sequence. just remember coil 1 then coil 2 then coil1-reverse, then coil2 reverse and repeat.

don't fall for the 'high voltage' power that people unfamiliar with the proper application of steppers seem to recommend as a starting point without understand the proper application of steppers, drivers or power supplies.

the ONLY reason you EVER need too increase voltage is to increase power.
power is based on the APPLICATION.
power increases proportionally with voltage.
iron loses, that is heating, increases with the square.

the APPLICATION requires 1.5 volts. maybe 3. EVERYTHING else is wasted as heat, both in the chip and the motor.

what is the real pity is that to compensate for poor engineering is the selecton of circuits that allows for the poor selections of power and fool one into thinking they did something right.

I have to say that it is getting tiresome to keep seeing people give incorrect advise.

// rant mode off, just