Re: [CAD_CAM_EDM_DRO] Re: Servos and Controller boards: an apology

"You don't of course have to contribute back anything but then that

> leaves us exactly where we are: Stuck with low cost finished units
> that have a warranty and work. You will rob someone of a learning
> experience many times more valuable than the mere cost of the unit."

Easy there Tiger!, all i did was ask the question, based on the "dont ask
dont get" philosophy.
I am a complete amatuer with no conventional training in electronics which
is why i asked, thanks for your input. However i am not the only amatuer out
here and whereas i may not be able to make any great contribution to the
field of electronics ( actually you can be certain there!) i have built a
cnc stepper board ( from a kit) and a cnc router good enough to make boards,
from scratch using a lathe and mill/drill so i maybe able to make some small
contribution to others who like me dont have the funds to simply buy what is
required.
Thanks again all who answered my posting.

somewhat wiser
Nick

----- Original Message -----
From: "caudlet" <info@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, April 13, 2004 2:20 PM
Subject: [CAD_CAM_EDM_DRO] Re: Servos and Controller boards: an apology


> <snip>Why don't we give that same encouragement to the poster who
> started
> this thread? I have no idea what Nick already knows about servos, but
> He has asked us to help him "know" more. Are we going to answer his
> question??? (What can YOU tell us about high current switching
> layouts, mosfet drivers, and such so that WE DON'T have to get a T0-
> 220 in OUR forehead?!?!?)</Snip>
>
> Your right Ballendo. What was I thinking? I made the assumption
> that this person was not a power switching analog/digital design
> engineer.
>
> Nick: To my knowledge there are no "kits" or build-it-yourself
> schematics of closed loop servo controllers suitable for CNC
> control. I don't know the precise reason for the dirth of
> information other than I suspect that those of us who have actually
> done a design using descreet available components want to perpetuate
> the concept that given the scope and complexity of the project it
> makes sense to buy it commercially. Obviously this is self serving
> since if you built your own then the guy that spent all of his time
> and effort to build, test and market his design will go hungry.
>
> I hereby encourage you to pursue the design and building of a DIY
> Servo controller.
>
> The first thing I would recommend is to get application notes from
> the main suppliers of power FET's about gate drive techniques and
> driving highly inductive loads. The acquisition of a high speed
> digital storage scope will help you analyse the nanosecond voltage
> transients. You will also need a high frequency current probe as
> well. Build up a few of the examples and you will learn a lot from
> the component failures. (Note: buy yourself a good set of googles).
> If you already have done this type design I apologize for assuming
> you haven't.
>
> After you have mastered the power part of the equation it's time to
> switch to the control side. This will be an excellent learning
> experience for you.
>
> There are some good books on feedback/loop design and
> characteristics but I would recommend a solid background in higher
> math prior to reading them. Possibly there are some self study math
> courses you can acquire. You will want to investigate all of the
> concepts then check the newer generation of chips. As electronics
> has progressed more and more functions have been rolled into fewer
> and fewer components. This integration will make your design
> smaller and more cost effective but brings with it the challenge of
> tiny circuits and multilayer PC boards and possibly the skills to
> deal with PLA's and programmable controller (embedded controller)
> chips. There is, of course, the option to use older analog and
> digital chips but you will definitly need to go back and review the
> technical books on proper analog and feedback loop design. Lacking
> a few years experience of laying out sensitive feedback circuitry in
> close proximity to high current switching components be prepared for
> a lot of board revisions on your initial design.
>
> Should you elect to use some of the newer SMT chips in your design
> you will have to invest in the specialized soldering tools for that
> technology or develop methods the average hobbiest can use.
>
> You will probably need some mechanical test fixture to be able to
> simulate varying loads and fault conditions prior to your final
> design. At the end of this you will have something you can
> contribute back to the group and then you can setup a forum to
> answer all of the questions you will get when their copy of your
> design built of perfboard and soldered with a hot rock doesn't work.
>
> You don't of course have to contribute back anything but then that
> leaves us exactly where we are: Stuck with low cost finished units
> that have a warranty and work. You will rob someone of a learning
> experience many times more valuable than the mere cost of the unit.
>
> I would be glad to help you with your quest except I have my own
> learning experience going with all of the other stuff involved with
> CNC control and I am kinda busy.
>
> I don't want to stiffle anyone from being the next Art or Mariss or
> Ray H. Everything is doable. We often make the stupid mistake as
> engineers of assuming that if something is already available cheap
> that it doesn't make sense to DIY. Who knows maybe you will
> discover a way to build a Servo Control for 12 bucks! We all await
> you triumph!
>
> Now if I can just talk somebody into explaining how to build your
> own 68,000 MFD 100VDC filter cap (they are WAY too expensive IMO) we
> will have one more piece of the true build it yourself machine.
>
>
>
>
>
>
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