Re: [CAD_CAM_EDM_DRO] Xylotex / RapidSyn/ Power Supply help?

In a message dated 12/13/2002 3:44:14 PM Central Standard Time,
volitan@... writes:

> I used the search function on the board to determine what kind of power
> supply to use, honestly, I'm lost again. Rectifiers, uF's, Caps and
> regulated, unregulated my head is spinning.
>
> Can someone dumb this down for me? I want to know if I can go to the Radio
> Shack and get a "Wall Wart" (figured that one out on my own:) ) To drive
> these things? I won't require a lot of torque from them, as for now they'll
> (hopefully) just be spinning freely on my desk.<<

David:

I don't know ANYthing about these Xylotex drivers, whether they are efficient
bipolar-chopper, or the "old" unipolar "L/R" type. So I can't really comment
"intelligently" about your situation without ASSUMING something, and I hate
to do that without KNOWING! But you say (below) these have 4 terminals for
the motor-wires. That would indicate they are almost-certainly
"bipolar-chopper drives". And you say your motors have SIX wires, which
means they are "unipolar" motors. Though I have never fiddled with a like
situation myself, I understand from reading here for weeks that one CAN use a
"six wire motor" as a "four wire" simply by NOT connecting two of the six,
and insulating the ends. OBVIOUSLY, the CORRECT two must be
insulated/not-used! You can use an ohm-meter, and find the three leads of
one coil, two "ends" and one center-tap. Select one of the two ends, and
"tape it off". Do the same for the other three wires. For this, it makes no
difference "which end" you so discard. Now you should have TWO pairs of
wires with a low DC-resistance between the two of each pair, but NO
connection between the two pairs. Now you have, for our purposes here, a
"4-wire motor". Connect those to the drive's 4 "motor terminals", making
sure you connect the pairs of a winding to the correct pair of terminals, and
likewise for the second winding. If you "goof" there, it simply won't run at
all.

Making an UNregulated DC power-supply with a transformer, rectifier, and a
filter-capacitor is really simple, but I can well-imagine how intimidating
this would be to a rank beginner in things-electrical. I do not know a
title, but I understand from reading here and like places that even Radio
Shack has "how-to books" on various electronic topics, and surely one or more
on POWER SUPPLIES.

Can you "read" a schematic? Do you know the difference between VOLTAGE and
CURRENT? Do you realize that the "OPEN-CIRCUIT" DC-voltage (that is, "no
load applied") of a rectified and filtered AC-voltage is about 1.4 times the
"RMS value" of the latter? That is, if you run the secondary of a "12.6 VAC"
transformer through a "full-wave bridge rectifier" and connect a
filter-capacitor across the output of that, and then measure the resulting
DC, no load (yet) connected, you would read about 1.414 x 12.6 (assuming the
transformer and your "line voltage" of 120 VAC are "nominal"), or about6 17.8
VDC. (But if you apply a load, this will drop in voltage).

> Also, months ago, I had a web site bookmarked that would help me figure out
> the wiring on the stepper motor. It told you where to put your meter to
> figure out what wire was most likely what, to get you started. Anyways it's
> a dead link now. The xylotex has 4 places for wires, the motor has 6 wires.<
> <

See above.

Lotsa luck! Jan Rowland>

>

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