Re: [CAD_CAM_EDM_DRO] Stepper Motor Driver

Blue wrote:

>Hi,
>
>I was going to use this driver with 50oz motors of 1 amp using a power
>supply of about 20 volts. The machine would be quite small for
>drilling/routing circuit boards.
>
>

Well, you would need to add resistors. A 1 Amp/winding motor would not
have a 20 Ohm winding resistance, or it would go up in flames.
So, you would need to add 2 resistors of about 19 Ohms (assuming the
motor drops about 1 V at 1 A) at 360 W. Each motor/drive combination
would need 720 W from the power supply, so a 3-axis system would draw
over 2 KW!

>Speed is not really an issue but I wouldn't want o wait all day for it to
>finish a job. I thiught it was a cheap alternative to proper drivers.
>
>

Well, you will get your 50 Oz-In when standing still, but at 60 RPM, you
might have only 5 usable Oz-In, because of R/L and resonance problems.
The performance of such a drive is going to be so abysmally below a
good bipolar microstepping drive that it is almost impossible for someone
who has not seen it with their own eyes to believe.

The IRFZ44 transistors are not properly driven to saturation by a 5 V
power supply, which is what the logic supply voltage is. The logic signals
are not opto-coupled, which may cause noise problems in a multi-axis
system. There is no provision to control the inductive energy when one
of the transistors is turned off, which may cause the transistors to be
damaged by this energy.

Yes, it is a cheap alternative. They left out the last 35 years of
development
in stepper drives.

Jon