Re: Before I make a mistake, what do I need to know?

--- In CAD_CAM_EDM_DRO@y..., Chris Stratton <stratton@m...> wrote:
> > As Chris S mentioned, you have some of the venerable IBM printer
> > motors: 2°/step, 1.4A (so they could use "modified" 1/2 stepping,
> > where the current is increased when a single phase is active.
>
>Nifty idea! Got any clever implementations?
<snip>It may be better to switch the chopper reference voltage
>between two levels.

Yes. The reference voltage is set up with a divider using .7071:1 or
1.414:1 The resistor(s) in the divider are switched in and out of
the circuit by anything from a 2n2222 transistor to a gate. The
transistor (or gate) is driven by the enable/disable lines from the
translator (going to the h bridge). Idle is handled in a similar way,
using a "missing pulse detector"(can be a 555) and r/c for timing.

Of course, there are MANY ways to implement this, the suggestions
above are just some ways I'm familiar with.

SGS thomson, now ST, has the process outlined in their l298 and l6203
literature. It is also discussed in the Erikkson driver chip app
manual, an address or phone number for which was given a long while
back on this list. (PIK power)

>(Or were you going to run the windings at rated current only
> when only one is on, and reduce for both phases on?).
<snip>

I've had no problems with these motors running 34v 2A(when single
winding activated) but I DO have an auto idle which kicks in if the
pulses stop. Without this, the motor may be over-driven by this
scheme...

Hope this helps.

Ballendo