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willheg
09-10-2008, 03:40 AM
hello people

this is my first post on here and i'm looking at building a cnc machine

anyway i'm just woundering weather anyone knows of where to get any easy driver boards to drive the motors i'm looking at getting

the motors are rated at 18-60v and are 4.2 amp and Phase Resistance (ohm) of 0.9

i'm looking at the A3977 board but not to sure if this one will be ok as i'd like to run about 48v to the motors to make install easy

i also have a 48v motor to drive the spindel which is why i'd like to drive the steppers at 48v (so i can just have the one transformer but don't think the controller board is good enought for this

sorry if this sounds mixed up but i'm rushed for time tonight and just thoguht i'd get my question out there as soon as i could

anyway hope someone out there can help

Cheers
William

patndel
09-10-2008, 05:16 AM
Hi William,

Not sure which particular flavour of A3977 based board you were looking at, but these chips from memory have a max working voltage of 35v and about 2.5A.

If your motors are 6/8 wire motors you'll have the option of running in bipolar series which will have the current requirements, and you will get away with it, but you need to limit your supply to about 30v to allow for back emf.

If thats not an option, you'll have to go for a beefier drive, something like a gecko 201 which can handle upto 7A/phase (with heatsinking)

HTH ... Pat

willheg
09-10-2008, 06:16 AM
thanks for the reply

the reason i ask is because i'm looking at home duilding the boards but don't want to spend to much as you may well know money is tight for me these days

the gecko for memorie is quite expenseive but that is something like i'm after but just want a home brew if at all possible, don't know if anyone has any links out there and just thought there may have been a way to maybe hook up extenal Power Mosfets to the driver then hook them to the motor or something but yeah still trying to work out all the ins and outs before doing to much

the other one i looked at was an l297/l298 but still no ideas on this

also looked at the pic step but don't know on this and would i need to programme the PIC16????? to run or will it work fine

anyway must fly any more help would be great

cheers
William