Kirk Wallace wrote: > On Wed, 2008-04-16 at 16:14 -0700, Kirk Wallace wrote: >> On Tue, 2008-04-15 at 20:42 -0700, Kirk Wallace wrote: >> ... snip > >> I am wondering if this is just a simple H-bridge with current limit? If >> anyone has more information on this drive, I would appreciate hearing >> it. > > Looking more closely at the driver, reveals it has three MC1455 (NE555 > compatible) timer/oscillators and an unknown FUA3302. The oscillators > must be doing some sort of power conversion. I was wondering why there > seemed to be allot of extra transistors and why the motors buzzed even > at rest. I need to some more poking around with the scope or voltmeter. >
It sure looks like a unipolar drive to me. They are probably doing half-stepping, which would give you the counts per inch that you think you have. Power is applied to the two center taps, thru two of the transistors which probably act as choppers to control the current. The other four transistors connect the ends of the windings to ground. If you call the windings 1 and 2, and the two ends of each winding A and B, half stepping would be something like so: 1A only 1A and 2A 2A only 2A and 1B 1B only 1B and 2B 2B only 2B and 1A repeat That is one full electrical cycle, four full steps, eight half-steps. It might be enlightening to trace out as much of the power circuit as possible and post it, if you are interested in reverse engineering the drive. I've done a little power electronics, and I'd be happy to take a look and see what I can figure out. Regards, John Kasunich ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
