power config for serial vs. parallel stepper coils

i have an old home-built mill that i'm trying to resuscitate. the old driver board was 5-wire unipolar, and i had to write my own EMC hal driver to control its raw phase sequences. then when hal was rewritten (many years ago), my driver no longer worked, and i never liked that board anyway, so i've now purchased a new one.

the new driver board is a "Quadstepper", from Sparkfun: www.sparkfun.com/products/10507

the driver chips are Allegro A4983: dlnmh9ip6v2uc.cloudfront.net/datasheets/...datasheet-123643.pdf

i asked this question over at sparkfun, but gotten no reply. i'll bet this forum is a better place for questions -- i need some advice on setup.

my three 8-wire steppers are rated at 7V/primary, 1.2A. (the 7V is printed on the motor, the 1.2A is from googling the p/n and finding someone else's quotation of the specs in a portuguese forum. so the 1.2A number is less reliable, but lets assume it's right, for now -- if anyone has an old Astrosyn catalog, i'd love to hear from you.)

the variables as i understand it are these: the motors are 8 wire, so i can run them either in series (raises voltage and lowers current) or parallel (does the reverse). in addition, the quadstepper driver chips do current limiting -- i guess this is really the part i'm having trouble with: how the current limiter affects the power supply requirements.

if i run the coils in parallel, i've read that the current requirement goes to 1.414 times the rated value, or 1.7A. and since the motor's power requirement stays roughly constant, the voltage goes down by .707 to 4.9V. so, can i run my motors from a 5V supply, using the current limit control to keep only provide 1A (the quadstepper max) to my motors? or should i instead run them in series, at 7V * 1.414 = 10V, so that they need only .85A? or, am i misunderstanding the parameters entirely? can i use the current limit the way i'm describing?

i assume that given my rated voltage, and serial or parallel hookup, that these are my only power supply options -- 5V or 10V. is that right? 12V supplies are a lot easier to come by...

many thanks in advance,
paul

Hi

Unless I am completely missing something the spec sheet says

Power input (barrel jack) needs to be less than 30V and supply enough current for your specific stepper motors.
24v sounds good and easily sourced.

Normally all voltage / current considerations are taken care of by jumpering the driver ( or looks like potentiometers on this board) to the required max output amperage and the voltage requirement to provide the amperage is dealt with by the driver.

These are Arduino type drivers for small robotic applications primarily. You may find problems getting them wired for max current (which you need with such small steppers) without overheating, even with additional heat sinking.

For simplicity I would recommend you use something like the 2M542 driver which will cover right up to 4.2A if you decide to upgrade steppers later. If you can wait you can get them for under £30 all in from Hong Kong and they are just jumper/connect/forget heat sunk boxes which will take a 48v supply for a good bit of umphh behind them.

I use these and their larger variants on all my machines now, they are smooth in microstepping and have not given me any problems yet

regards

thanks for filling in the gaps in my current (heh) understanding. i knew i was missing something.

and thanks for pointing out the newer stepgen features. good stuff.

looking forward to getting this thing working again: www.foxharp.boston.ma.us/photos/mill
it's not much, but it's mine. i built it in the mid-90s, and used some DOS s/w that came with the plans for quite a while. then eventually i found EMC, which was great until the HAL change, and then my driver bit-rotted.