Will These Work (Stepper Motors)

I have a home made unipolar stepper controller using the UCN5804B. I got three matching motors off ebay for $6.00 ea. the motors are marked:

Superior Electric / SLO-SYN
1.25v
3.8a
Hold 60 oz. in.
200 steps

I am building my own design table with a working area of 18" x 18". Here are my questions:

1 - Will these have enough holding (60 oz) to do the job.
2 - Since they are rated at 1.25 volts and 3.8 amps will I still need to use high wattage resisters if I go to 12 vdc, and if I do, what would the value of the resistors (Ohms and Watts) be.

Thanks,
George
(aka Hawkeye)

3 ohms, 35 watts will get you 3.33 amps to the motors. 2.5 ohms gets you 3.92 amps to the motors. All this according to StepperCalc. www.e-zflight.com/files/stepcalc102.zip

You can't drive these motors off the IC, you will need transistors or FETS to drive them.

The above calcs. assume your using FETS for the outputs.


Eric

Thanks Balsaman,
Do I need to find a new driver or some new steppers?
What About These - Good buy or not (can they be used???)

http://cgi.ebay.com/ws/eBayISAPI.dll...category=42920

I was thinking that all I needed to do was maybe drop the voltage to 5 vdc (still 4 times higher than rated) and throw in some 2 ohm 10 w resisters and be flying. I am still very new to all this and appreciate any and all comments.

Thanks,
George
(AKA Hawkeye)

bump

I think that the UCN5804B is good for only 1.25 amps. You can use the board you made to drive FETS that drive your existing steppers. I will see if I can locate a schematic if you need one.

Eric

That would be great, Thanks Balsaman.
Did you get a chance to look at the steppers on the ebay link?
what do ya think?

Thanks again,
Hawkeye

Those steppers will work great, but are still over the current of the UCN5804B.

Also, if you go with the first motors, go with 12 volts, not 5.

Eric

Great, I will.

Here is the schematic of the stepper driver I built:

I am scouring the web trying to find the additional FET circuit I need.
I am going to use an old computer power supply. It's 12vdc is rated at 7.5 A and the 5vdc is 21 amp. I think this should be plenty.

Balsaman,
Is this more like what you were talking about (Driver)?

http://www.piclist.com/techref/io/st...step/index.htm

Thanks,
George

The 5 volt side of that PS wiull be plently if that's how you will drive the motors. If 12 volts it's undersize. You need to add up all the winding currents. 3.8 amps x two windings x 3 motors.

That driver is also a little light for your motors.

Here are some that might work: www.alltronics.com/kits3.htm
3rd from the bottom of the page.

Eric.