[dertsap]

Xylotex can run 3amp per phase , i have a question , my motors are 4.5 amp unipolar , So how i understand things is connecting unipolar motors to bipolar they will take less amps , would the Xylotex board handle these motors

thanks
curt

[ger21]

The Xylotex can only supply 2.5amps. Here's some info from their data sheets.

Unipolar Motor Note:

When Setting Vref for a UNIPOLAR rated motor, use a current of 50.0% of the rated unipolar current, when wired for series mode. EX: Unipolar rated at 2.0A, when wired in series mode would be setup for 1.00A, or Vref of 1.44 Volts. Half winding mode would use the full 2.0A rating, Vref = 2.44V.
The drive will work with three type of stepper motors, 4-wire, 6-wire or 8-wire motors. 4-wire motors are truly bipolar, and can only be run as such.
6-wire motors can be wired two ways to work with the bipolar drive.
The first is half-winding. In this method, one end wire, and the center-tap wire of the phase is used. The other end is insulated and left unused. This method uses unipolar nameplate current specifications, and will produce nameplate torque.
The second is series winding. In this configuration, the center-tap is insulated, and unused. This method uses all of the wiring per phase, but has double the number of wire turns as half-winding or unipolar mode. Because of this, the amperage requirement becomes half the nameplate rating. Because the wire in the coil can handle more current than ‘half’, motor manufacturers will often “boost” the torque rating by specifying currents up to 71% of unipolar rated current while running in series mode. This is fine for FULL step motor drives, but not necessarily so good for microstepping drives. Using this much can smear microstepping smoothness and accuracy. Any extra torque achieved by this method will generally be lost to machine vibrations due to loss of microstepping smoothness. The best performance will be somewhere between the 50% and 71% current rating.
The advantage of using series winding is that lower power drives may be used. For example a unipolar motor rated for 4.0A/phase is over the 2.5A/phase maximum of the XS3525/8S-3. Running in series requires only 2.0A/phase to achieve the same torque. The disadvantage of this method is that it raises motor inductance, which in turn, slows motor coil charging time. Since proper torque is reached only when the coil has charged to the required level, the longer it takes to charge, the longer until full torque is achieved. This leads to slower full torque stepping rates. Conversely, a half-winding configuration requires full nameplate rated current, but if the drive is capable of this, the advantage is that rated torque can be achieved twice as fast as series winding (using the same voltage, when comparing half-winding and series).

[dertsap]

a simple yes or no would have been sufficient LOL , but thanks alot for the info bud that will be most definitely valuable to me , i ve been al over the internet looking for a chopper driver be it unipolar or bipolar that can handle these motors and i can t find anything that is close to my price range and can handle that amperage , i don t really see it necessary for my application to have microstepping , everything that i have done so far is in full step and it works for me , but there really isn t a lot to choose from ( at least in my budget) next best i see sofar is gecko and they are too pricey right now ,think im stuck with the fet 3 for now

[pminmo]

i have a question , my motors are 4.5 amp unipolar , So how i understand things is connecting unipolar motors

How many wires are the motor? The l297uni on my site should run a 4.5A unipolar.

[dertsap]

hi Phil i was talking to you earlier this week about that board , ive been going full circle back to your site and looking at the board , the only thing that worries me is my limited knowledge of electronics when it comes to building a board , but like i say i search the net and go check out your site and look again at that board , i think that would probably be my best choice , how has your friend been making out running the 6 amp motor?
the motors i've got are 6 wire , they are 4amp , 4.5 was stuck in my head because i was testing a new motor today which will be back on the selling block , not impressed with it
but if you think it is somewhat idiot proof (not that i am one ) i'de like to try it ,
as for the parts go should i get them from mouser and the chips from TI

[pminmo]

He is still waiting parts. Send me a PM, maybe I can help in some way.

[dertsap]

phil this may sound dumb but what do you mean by PM

[randyf1965]

Private Message

[dertsap]

got it thanks