Re: [CAD_CAM_EDM_DRO] Stepper power supplies, unregulated or regulated? Switc...

I'd like to contact you off line Jan..but the server rejected your address.
Where do I send my off post messages to?
Smoke
-----Original Message-----
From: JanRwl@... <JanRwl@...>
To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
Date: Friday, December 01, 2000 8:07 PM
Subject: Re: [CAD_CAM_EDM_DRO] Stepper power supplies, unregulated or
regulated? Switc...

>In a message dated 01-Dec-00 18:34:48 Central Standard Time,
>mcamp@... writes:
>
>
>> Can anyone tell me what the ins and outs of power supplies are? I am
>> planning on buying a couple of Gekko g201 stepper drives and 720 in. oz.
>> motors. Should I get a power supply for each drive or one big power
>> supply? Unregulated or regulated? Switched or linear?
>> Any low cost suggestions? Bob
>>
>>
>>
>
>Bob:
>
>I am an ignernt, uneducated "tinkerer", but I have made many devices which,

I

>think, operate using electric energy, and I am still alive. So, having not
>quite yet reached the degree of heinous andunsavory attitude that would
>preclude my willingness to be helpful, I will here try: A "DC Power

supply"

>consists generally of a transformer, rectifier, filter-capacitor(s),
>voltage-regulator, current-limiting device(s), if any, and

output-terminals.

>Some types might not use a transformer, but those would probably fall into
>the category of cheapo home-entertainment devices and apparatus designed by
>those with little respect for comfort nor extended life-span.
>
>Generally, steppers of the type you mention (over a couple-hundred oz.in.)
>require such low voltage and high amperage that the common,

usually-cheaper,

>and easier-for-dolts-such-as-me "linear regulator" supplies are not
>indicated. "Switchers" for high-current applications require considerable
>experience with that particular type circuitry, as "peculiarities" sneak in
>there when you get into more than, say, five amps, particularly if the
>voltage is below, say, 20, and you are trying for at least 95% regulation.
>Possible, but it takes a guru who has been sequestered in a closet in the
>design-floor of a many-decades-established DC-supply/user manufacturer.
>
>Anything with sufficient power (steppers) to CNC such as a Bridgeport

should

>be built ONLY with bipolar "chopper drive" motors and circuits, and it will
>cost you much less both initially and in later-grief if you don't, to just
>BUY ready-made, specific-for-the-motors-in-mind supplies and drivers, often
>in the same "box". I have just finished cobbling two new
>application-specific CNC lathes with Superior Electric KML092- motors, and
>their SS2000DP4-FF dual-driver/supply (toroidal transformer,

bipolar-chopper,

>DIP-sw. settable amperage, etc.), and I wanna tell ya! I wonder, now, why

I

>ever fiddled with the old unipolar tapped-windings MO-92 motors! The KM
>stuff (bipolar) are far-and-away more powerful for same-size, and NO

heating,

>etc. And "break your arm" torque on the lead-screws! WOW! Good I

installed

>"all-windings-off" switches on the control-panel (the said driver-box has
>that connection), as setting-up would be otherwise IMPOSSIBLE with

power-on!

>
>IF the drives you specify can be had WITH supply, as are the ones I

mention,

>then it'd be much more economical to get a "single box" with both (more?)
>stepper-drives AND one power-supply in same box. But maybe huge ol' motors
>like that will REQUIRE separate supplies for each driver? I have never

done

>the math nor catalog-search on such since about '85, when I built a MONSTER
>with MO-172- and -112 motors. In those days, "bipolar" was not yet a gleam
>in S.E.'s eye, nor did I yet know how to tell time.
>
>I can tell you this obvious detail: use wire to the steppers with at least
>1000 CM per amp, and either nicely- and expertly-solder all joints, even
>where a wire is terminated with a "lug", or, use Amp type "gas-tight"

crimps.

> A whole science in itself, requiring specific experiene. Best: SOLDER,
>using Ersin multicore 60-40! Keep all "signal" lines (from computer to

box)

>SEPARATED from stepper-lines, and, if they must cross, TRY to make 'em

cross

>close to 90� (�5�!). Cause, if you run the "logic" lines parallel to 5, 10
>amp motor-lines with chopper-current-control for, say, 4", you will have
>MULTITUDINOUS knashing of teeth and untoward syntax!
>
>Nuff. If you have specific, "Yeah, but what about..." kinda questions,
>e-mail me direct. I am a reTIRED old geriatric, so, won't cut into my

income!

>
>Regards, Jan Rowland, Troll with attitude
>
>
>
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