Re: [CAD_CAM_EDM_DRO] half step shaping was Re: Newbie question. Second try

Hi Jerry,

Yes, initially it sounds backwards, BUT, (see below)


Carol & Jerry Jankura wrote:

>
> Hi, Alan:
>
> I was weeding out old messages, came across this one, and had a question, so
> here goes
>
> |Let me quote from an earlier post from Mariss:
> |
> |
> |" Here are the rules:
> |
> |4-wire motor. No problem. Use the rated current and you will be fine.
> |No options here.
>
> Understand this one.
>
> |6-wire motor (unipolar). This is the same as the 4-wire except the
> |windings are center-tapped and the center taps are brought out.
>
> |You have two choices here; half-winding or full winding. You use half-
> |winding if yours is a high speed application or full winding if it is
> |a low speed one. Use the unipolar current rating for half-winding and
> |1/2 that for full winding.
>
> Don't understand this. It would seem that, when used in unipolar mode, you'd
> connect the taps to the + voltage and the ends to the driver transistor
> collectors. And, you'd set the series resistor to drive the "rated" current
> through the coils. Right?

This is talking about BIPOLAR USE (otherwise you wouldn't have the
choice of full or half winding). The unipolar rating is current for a
single winding, when driving BOTH, you'd have TWICE the ampere-turns,
which would be too much (humm... musta been why that motor ran HOT!),
more then the motor wants!

>
> And, for bipolar, you'd either drive half the coil at full current, or the
> full coil at half current rather than as you've stated. It would seem to me
> that you'd want to maintain the same number of amp-turns for each coil
> regardless of whether you were using the full coil, or half of the full
> coil. Where am I missing it?

YES! You've stated it as I commented above! Mariss' is only talking
about BIPOLAR use.

Hope this helps!

Alan KM6VV

>
> -- Carol & Jerry Jankura
> Strongsville, Ohio
> So many toys, so little time....