Re: [CAD_CAM_EDM_DRO] Digest Number 741
Posted by
beer@s...
on 2000-10-05 13:29:04 UTC
On 5 Oct, CAD_CAM_EDM_DRO@egroups.com wrote:
would guess that you're running some healthy motors.
near the switching transistors.
MOST IMPORTANT, by far, is to have a good board layout and use good
grounding practices. This cannot be stressed enough !
stepper board could arise that would screw up the PS, but if it did, it
would have to be a pretty crappy supply and definitely not worth using.
And there's no need for the regulation a typical switcher supplies when
used with a chopper drive, meaning that the extra cost is just money out
the door. ( This is certainly NOT the case with a non-chopper drive,
though )
OTOH, switchers do use nice fast caps, of the kind I mention above.
My opinion would be that if you have a quality switcher around of
suitable capacity, there's no reason not to use it. But there's no
reason to go out and buy one if you don't.
the choice for low level high gain circuits. But if the EMF created by
a transformer has ANY effect on your stepper driver, you have some other
major problem.
I cannot conceive of how any external "interference" likely to be
found in a typical shop could influence the performance of a properly
designed, properly constructed stepper controller.
Improper design, poor construction, LONG cable distances, or bad
grounding ( inside or outside the box ) certainly will, but a well
designed, well built controller six feet from the PC and six feet from
the machine it controls will not suffer from almost any external
electrical influence.
Alan
--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta
> I used the 1N4934, then 1N4936 diodes recommended at first and smokedWell, the 851 is both higher voltage and higher current, so a person
> some chips.
> Switched to MR851's and not only have not seen smoke, I can "Back
> Drive" my machine(s) (steppers working as generators) without blowing
> the boards. At least, so far! KOW.
would guess that you're running some healthy motors.
> I believe the power supply is a significant part of the success atMore important is to have a fast, low ESR electrolytic ( 220uf or so )
> higher volts/amps. Mine use a 40,000mfd electrolytic, with a hi-freq
> disk cap and bleeder resistor.
near the switching transistors.
MOST IMPORTANT, by far, is to have a good board layout and use good
grounding practices. This cannot be stressed enough !
> Calcs(and boards) I have seen would allow a 10k mfd cap.Or less. ThisIt's POSSIBLE that some sort of beat frequency between the PS and the
> is for a typical bridge rectified linear PS. Have not had problems
> with inrush current. I have heard conflicting info re: switching PS
> with chopper-drives so I don't do it. Mariss???
stepper board could arise that would screw up the PS, but if it did, it
would have to be a pretty crappy supply and definitely not worth using.
And there's no need for the regulation a typical switcher supplies when
used with a chopper drive, meaning that the extra cost is just money out
the door. ( This is certainly NOT the case with a non-chopper drive,
though )
OTOH, switchers do use nice fast caps, of the kind I mention above.
My opinion would be that if you have a quality switcher around of
suitable capacity, there's no reason not to use it. But there's no
reason to go out and buy one if you don't.
> Also like to use toroid transformers, but don't really know how muchNothing wrong with toroids at all; small, more efficient and undoubtedly
> they're helping, since I haven't compared with "box-style". Why mess
> with success?
> I do think the toroid helps if things are a tight fit. Their EMF is
> "contained" better so it is less likely to interfere with something
> else close by.
the choice for low level high gain circuits. But if the EMF created by
a transformer has ANY effect on your stepper driver, you have some other
major problem.
I cannot conceive of how any external "interference" likely to be
found in a typical shop could influence the performance of a properly
designed, properly constructed stepper controller.
Improper design, poor construction, LONG cable distances, or bad
grounding ( inside or outside the box ) certainly will, but a well
designed, well built controller six feet from the PC and six feet from
the machine it controls will not suffer from almost any external
electrical influence.
Alan
--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta