6 Wire Stepper help

I have a 6 wire stepper that consists of 2 center tapped windings. it's about 8 ohms per winding with a center at 4 ohms. it's 200 Step 1.8 deg/phase.

I programed an arduino with a basic stepper controller sketch and hooked it up to 4 MOSFETS and tied the center taps to +.

I get a stepper that turns, slowly, and has very little torque. I fix printers at work and I have seen some steppers FLY, im sure this can go faster.

the problem i believe is that the stepper controller that i programmed only has one MOSFET on at all times, and some drivers I have seen keep 2 on and flip-flop them both.

I have been trying to get this to turn and be fast and torque like for hours and im kinda getting fed up with this thing! lol

does anyone have anything that is made for driving this type of stepper? maybe someone has a sketch written in C that i can compile to a chip and run this thing?

Thanks!

Post a schematic of your circuit.
Include the part numbers of the MOSFETs used, and the part#/manufacturer of the stepper motor.

well, the stepper has a number on it but it doesn't give me any info from the internet. It's a matishuya (i think...) i dont have it with me


I am unsure if i have the 4 winding wires on the correct transistor, i know the centers are in the right spot.

There is only 1 combination in which the shaft spins in a complete circle, so i assume it's the correct one. but when i increase the voltage or speed, the motor runs erradic.

Is there any way to tell which wire should be in what sequence? Im going crazy trying to make sure it;s right.

the arduino IC fires them 1, 3, 2, 4, 1, 3, 2, 4, 1, 3, 2, 4,

Metalfan1185 said:

well, the stepper has a number on it but it doesn't give me any info from the internet. It's a matishuya (i think...) i dont have it with me

Click to expand...

Post the manufacturer of the stepper and it's part numbers when you can get to it. We'll wait.

I am unsure if i have the 4 winding wires on the correct transistor, i know the centers are in the right spot.

There is only 1 combination in which the shaft spins in a complete circle, so i assume it's the correct one. but when i increase the voltage or speed, the motor runs erradic.

Is there any way to tell which wire should be in what sequence? Im going crazy trying to make sure it;s right.

the arduino IC fires them 1, 3, 2, 4, 1, 3, 2, 4, 1, 3, 2, 4,

Click to expand...

You probably have them in the right order, because otherwise it would just jitter back and fourth.

However:
1) What type of diodes are those you have on the inputs to the gates, and more importantly, WHY are you using them?
2) What is the value of the resistors from the diodes to the gates?
3) What is the value of the resistors from the diode to ground?
4) What are the part numbers of the MOSFETs?

ok, I have 2 motors with 6 wires that i would like to use. both have done the same thing.

the more important one:

Minebea-Matsushita Motor Corporation
23LM-C004-79W
NO. T6704-01
(this is exactlyl as listed)

and also:

SANYO DENKI
TYPE 103H5205-0345
3.6(ohm) 1.8 deg/step
LOT NO. 08609F






To answer the other questions:

The diodes in series with the Gates of the MOSFETS are to stop current from flowing back into the Programmable IC in case of the MOSFET Shorting out to the Gate. (The MOSFET uses >= 5V from a different supply from the arduino chip)

The resistor in series with the gate is 82 Ohms and the pull Down to GND is 1k

MOSFET Part Number is

Phillips TrenchMOS N Channel
PSMN035-150p

Metalfan1185 said:

The diodes in series with the Gates of the MOSFETS are to stop current from flowing back into the Programmable IC in case of the MOSFET Shorting out to the Gate. (The MOSFET uses >= 5V from a different supply from the Arduino chip)

Click to expand...

The diodes are reducing the maximum gate voltage by their Vf.

The resistor in series with the gate is 82 Ohms, and the pull Down to GND is 1k
MOSFET Part Number is
Phillips TrenchMOS N Channel
PSMN035-150p

Click to expand...

The PSMN035-150P is not a logic-level MOSFET. It's threshold voltage (where it begins to conduct) is typically 3v, but may be as high as 4v before the drain will pass 1mA current. It won't be fully turned on until the gate voltage reaches 10v.

Also, these MOSFETs have a rather large gate charge requirement of 79nC. It will take either a high-power driver or a long time to charge/discharge the gates.

I'm assuming you're operating your Arduino from 5v.

What is the current limit for your Arduino's I/O pins to source/sink? 20mA? 50mA?

You're really using the wrong MOSFETs for this application. It's like using a battleship to swat a fly. You need logic-level MOSFETs with far lower gate charge requirements.

You need to increase the gate resistors to decrease the peak current to/from the gates to keep within the Arduino's limits.

The resistor to ground is much too low in value. Use 5k or 10k for a safety pull-down in case the Arduino's output fails.

Get rid of the diodes in series with the gate resistor.

You also have not included flywheel diodes to keep the reverse-EMF from destroying the MOSFETs when they switch off.

Ok ,thanks..

I do have some TIP122 MOSFETs laying around...would those work? can you reccommend one

The only reason why i tried those MOSFETS is because I have a bunch of them. I mentioned i have a few TIP122''s and that's about it for the MOSFETs.

Im not sure how to tell if they are "Logic Level" like sgtwookie mentioned, If I were to purchase a more General-Purpose Logic Level MOSFET that can drive many different stepper motors, is the TIP120 the one to use? is there one that will work better?


Thanks for all this guys!

Alberto said:

TIP122 is a PNP you have to ground the common. TIP 120 the NPN is more recommandable.

Click to expand...

This is not correct.
TIP120, TIP121, TIP122 are NPN Darlington transistors.
TIP125, TIP126, TIP127 are PNP Darlington transistors.

You could use them, but you will see a Vce of around 0.7v with a current of around 1A.

You will need to use a resistor from the Arduino to the TIP122's base. I suggest somewhere between 330 and 470 Ohms.

To protect the transistors against reverse EMF from the stepper's coils when the transistors turn off, use diodes from each TIP122's collector to the stepper motor's +V supply, cathodes towards +V

Your motor 23LM-C004-79W is probably rated at 6 V. 1,2A. That is the rating of the 23LM-C004. If it look like the one in the picture than it should be that.




I would run it at 12 volts using one 4,7 Ohms, 10 watts ballast resistor on each one of the center tap.

For better torque, I would run the motor full step, that is 2 phases energized at the same time. But it could be also run half step, witch is one phase on then 2 phases on then one phase on etc. or wave driven witch is only one phase on at a time like you did. The torque would be less.

What I said before is if you use a very simple driver as in this drawing, using your TIP120's. No need for diodes, the TIP120 Darlington transistor is already protected internally. Much better performances are possible with a more sophisticated driver.



Well tuned by a software, using this driver, you could expect to run the motor at a maximum of around 300-400 RPM with an usable torque.

I would suggest that you try TURBOCNC to experiment with your motor at the beginning. It is a pure DOS software.

This video show my first driver built with TIP121's as per the drawing. The specifications of my motors are almost the same as the 23LM-C004. I drive them at 12 volts:

http://www.youtube.com/watch?v=JWe2OzRNOfc

Like I said this was my first driver, too complex and with useless gigantics heat sinks and fans. But it is working well (and cool!)

All this is just my 0,02$ as I am not an expert in any way.

Alain

(TurboCNC has a new version, V5 beta, that is windows based)

Here is something very fun.

Easy to use and eventually easy to modify to your taste if you know a bit of programming.

Sinceres congratulations to the authors!




Here is the reference in case you don't know about it already:
http://www.picaxeforum.co.uk/showthread.php?t=12629

Thank You all very much...

I will modify my existing circuit setup to how sgtwookie mentioned with the TIP122, resistor in series with the base, and reverse-emf protection diode.

as for the other posts...

yes the motors are similar, mine is a slightly different color, but other than that you couldn't tell the difference. I will try those Voltage and Current Specs.


now I know they can go pretty fast, but if you step them slow, do they hold the torque? like, say I wanted to have the motor turn 1 revolution per minute, I understand I have to watch the temperature of the motor coils and drivers and such, but will it stay in squence? or tick back and forth?


Thanks again for all your help. Steppers are kinda new to me

TIP120, 121 and 122 are all rated at 5A. The voltage differ but any of them will do at the voltage we are talking about here.

I would say that at one revolution per minute, if you run it full step, the motor will produce about his maximum torque. It will have to dissipate around 14 watts and it will become warm, maybe hot. As long as you can hold it in your hand, I mean as long as it is not burning hot, it is OK. They are made to run hot.

If your logic gives it the good scequence, there will be no reason for ticking back and forth.

I think the TIP 122 NPN power transistors have those extra diodes in them too............which should make the external diodes mentioned redundant.

zoot686 said:

I think the TIP 122 NPN power transistors have those extra diodes in them too............which should make the external diodes mentioned redundant.

Click to expand...

This is only partially correct.

The TIP12x series do have body diodes.

However, when the current flowing through a winding of the stepper motor and is suddenly cut off by the transistor, without a "flywheel" diode there will be no place for it to go except for blasting it's way through the transistor or the body diode.

When the current flow is suddenly stopped, the polarity across the motor's winding reverses as the field collapses. The peak voltage across the winding can be very high. It will eventually exceed the peak inverse voltage and/or the maximum collector-emitter voltage of the transistor, and they don't last long operating like that.

If you were using TIP122 (NPN) and TIP127 (PNP) Darlingtons in an H-bridge, you would then not need the diodes to +V, as both the TIP122 and TIP127 have body diodes. The TIP122 body diode would take care of any negative voltage excursions, and the TIP127 body diode would take care of any positive voltage excursions.

This thread is so old that you may not hear back from them.

You will find that you have two groups of three wires.

Start by using a multimeter set to measure low Ohms.

Find a group of three wires that have low resistance to each other.

For example, you may find that red, white and blue all have low resistances to each other, but no connectivity to the yellow, white and orange wires.

So now you have two groups of three wires.

In each group, you will have two wires that measure about twice the resistance between them than to the other wires.
For example, you might measure 4 Ohms between red and blue wires, but only 2 Ohms between red and white, or blue and white wires. In this case, white would be your V+ supply for that side of the motor, and red and blue would be the ends of the phases.

The Ohms I used for the windings are just an example. As far as resistance, your mileage may vary.

If you are using the motor as a 2-phase bipolar stepper, you would not use the center tap (white wire).