[slp_prlzys]

slp, the 5804 pin 1 is enable it has to be held to a logic low or you can wire it to ground, other than the led it won't do didly without enable low. Pin 3 is direction and pin 5 is step. Pin 7 is gnd and pin 9 is an option for 5vdc out or in. Dingy me I had a small instruction document put together, but didn't get it on the website. (its attached to this reply) Organization isn't one of my strong points. It's possible you could have blown one ore more of the FET's, were the running hot? Was your motor an 18V motor, or did you have some current limiting resistors in, or what do you know about the motor? R4 and R5 depend on the motor and power supply, and have to be calculated the same as the discrete board. You did compare your motor rating to your power supply correct?

hi pminmo, I moved my quest here, I hope it's ok,
I was going to start a new thread, but don't know what I should
put in the title,

First, I know nothing about motor, a little slow but I'm
learning. My motor is 5.2V 1.4A/phase, I know that my pwr supply
is not enough since it's only 1A, I was just testing it, would you
mind explaining what was happening If i.e. my test setup,
does the motor sucks too much current? ( I think the term was draw)
I haven't any resistor yet, since I haven't decided what type of
power supply I should be using, I'm leaning toward ATX supply,
with ************* hacks. I also got the steppercalc Balsaman posted,
to ease up on the calculation.

The FETs were hot before it killed the power supply and the board.
thanks for the doc btw, I sure am hoping your not losing your patience
on a newbie

[tachus42]

slp what FETs did you use on the board? Without resistors your motor would have been trying to draw about 4.5 amps per phase ie 9 amps total! Still the FETs shouldn't have been getting hot. If you used standard rather than logic level mosfets they would get only partially turned on causing them to get hot and then fail.

Another thing which could have happened is that your power voltage dropped under too much load. If it got down to less than 7 volts or so then the circuit wouldn't be able to supply enough voltage to the mosfets to turn them on properly leading to failure of the fets again.

Phil the max supply of the discreet unipolar board needs to be 30 volts with the given fets - the off fets will see twice the power supply due to transformer action of the windings.

[tachus42]

It appears we have made a mistake with the design of the discreet unipolar board.
I just had a look at the irfz44 datasheet - i had just taken it on face value that it was a logic level mosfet but it ain't. Everybody else did too right?

It should still work well under moderate load but if the logic power supply drops just a tiny bit then the magic smoke will get out.

A better choice for the mosfet would be a STP30NE06.