Steppers as rotary sensors

[Iman Habib]

Hi guys.

I've been thinking a bit about steppers as incremental rotary sensor today.

I guess its pretty simple to use them as sensors by just continuously
normalizing the signal and sampling voltage change (looking for highs and/or lows)
But that would only work well if the shaft moved at acceptable speed.
I think that to slow movements would not induce any worthwhile signal.

So my question is.

Would it not be possible to instead induce a small (small enough so the stepper
wont try to move) current through the coil, sample the signal strength that comes
back when the field collapses and calculate the position of the stepper between
the "teethes". Or are there any strange irregularities in stepper coils that would
prohibit me from effectively doing this or some other problems that might occur?

Of course there would be somewhat of a problem if the stepper shaft
was moving at the same time so I guess this kind of measurement would
only work at standstill or when the shaft is moving very slowly (right?).

Anyone out there that has links to sites related to this idea or has any
personal experience regarding this. I cant seem to find any websites
covering this matter.

regards
/iman


--
So remember, kids! Every time you download a song off the Internet, you kill a baby panda!

 

[default]

On Thu, 2 Oct 2003 16:36:44 +0200, "Iman Habib"
<imanhabibREMOVETHIS@eml.cc> wrote:

Hi guys.

I've been thinking a bit about steppers as incremental rotary sensor today.

I guess its pretty simple to use them as sensors by just continuously
normalizing the signal and sampling voltage change (looking for highs and/or lows)
But that would only work well if the shaft moved at acceptable speed.
I think that to slow movements would not induce any worthwhile signal.

So my question is.

Would it not be possible to instead induce a small (small enough so the stepper
wont try to move) current through the coil, sample the signal strength that comes
back when the field collapses and calculate the position of the stepper between
the "teethes". Or are there any strange irregularities in stepper coils that would
prohibit me from effectively doing this or some other problems that might occur?

Of course there would be somewhat of a problem if the stepper shaft
was moving at the same time so I guess this kind of measurement would
only work at standstill or when the shaft is moving very slowly (right?).

Anyone out there that has links to sites related to this idea or has any
personal experience regarding this. I cant seem to find any websites
covering this matter.

regards
/iman

I don't think you have to worry about slow speed operation. I used a
stepper to generate a signal for another stepper to use as its drive
(using steppers as a "selsyn" system - turn one shaft the driven shaft
turns the same amount at a remote location - with two identical
steppers or a ratio with different step angles)

Anyhow I used an LM324 to sense the coils on the pickup stepper and
couldn't turn the signal stepper so slow that the remote wouldn't
follow.

I'll post my circuit on the alt.binaries.schematics.electronic if the
posting gods will allow it. Use the part on the "input side" to get
your sensing output.

It'll take an hour to scan and post it.


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[Mike Harding]

On Thu, 2 Oct 2003 16:36:44 +0200, "Iman Habib"
<imanhabibREMOVETHIS@eml.cc> wrote:

Hi guys.

And there's a lot of us! You have probably posted this message
to a couple of million people - maybe more?

Was it really necessary to post to:
alt.engineering.electrical,aus.electronics,sci.electronics.components,sci.electronics.basics,sci.electronics.design
?

Why not try just one group to start with?

Mike Harding

 

[Bill Sloman]

"Iman Habib" <imanhabibREMOVETHIS@eml.cc> wrote in message news:<blhd5s$c078e$1@ID-168056.news.uni-berlin.de>...

Hi guys.

I've been thinking a bit about steppers as incremental rotary sensor today.

I guess its pretty simple to use them as sensors by just continuously
normalizing the signal and sampling voltage change (looking for highs and/or > lows) But that would only work well if the shaft moved at acceptable speed.
I think that to slow movements would not induce any worthwhile signal.

So my question is.

Would it not be possible to instead induce a small (small enough so the
stepper won't try to move) current through the coil, sample the signal
strength that comes back when the field collapses and calculate the position > of the stepper between the "teeth". Or are there any strange irregularities > in stepper coils that would prohibit me from effectively doing this or some > other problems that might occur?

Of course there would be somewhat of a problem if the stepper shaft
was moving at the same time so I guess this kind of measurement would
only work at standstill or when the shaft is moving very slowly (right?).

Anyone out there that has links to sites related to this idea or has any
personal experience regarding this. I cant seem to find any websites
covering this matter.

About the only way I can see you getting useful position information
out of a stationary stepper motor would be by measuring the
inductances of the two sets of coils.

You could do this with very low AC currents, so it wouldn't generate
any torque. You couldn't use particularly high frequencies - the coils
are going to go self-resonant not too far above the maximum stepping
rate, and the iron path losses will become crippling in the same sort
of range - but you should be able to work something out.

There are motor-like parts designed for this sort of job, called
"synchros"

http://www.incon.com/products/prs/1292-ks.htm

shows an example. Analog Devices used to sell integrated circuits
specifically designed for decoding the outputs of these devices, but
I've not had any occasion to check on the status of these parts in
recent years.

-------
Bill Sloman, Nijmegen

 

[Alan]

"Iman Habib" <imanhabibREMOVETHIS@eml.cc> wrote in message news:<blhd5s$c078e$1@ID-168056.news.uni-berlin.de>...

Hi guys.

I've been thinking a bit about steppers as incremental rotary sensor today.

I guess its pretty simple to use them as sensors by just continuously
normalizing the signal and sampling voltage change (looking for highs and/or lows)
But that would only work well if the shaft moved at acceptable speed.
I think that to slow movements would not induce any worthwhile signal.

Even at slow speed as in single step, there is a breakaway function
and snapping to the new position. Don't really expect you could do it
that it couldn't be sensed, short of having a 3 foot long lever on the
shaft so that you could move it VERY slowly accurately against it's
internal magnetic field.

Also, use a high voltage stepper. A 24 V stepper turned will put
something out even if you turn it very slowly. Should be very hard to
get a non-detect.

Alan

 

[Rod Speed]

Mike Harding <mike_harding1@nixspamhotmail.com> wrote in
message news:m09pnv8gr6r5nnpfur0bquk70jk71hblkq@4ax.com...

Iman Habib <imanhabibREMOVETHIS@eml.cc> wrote

Hi guys.

And there's a lot of us! You have probably posted this
message to a couple of million people - maybe more?

In your dreams...

Was it really necessary to post to:
alt.engineering.electrical,aus.electronics,sci.electronics.components,sci.electronics.basics,sci.electronics.design
?

It does make a lot of sense to do that.

Why not try just one group to start with?

Because its much more efficient to include that lot instead.

 

[Jim Thompson]

On Fri, 03 Oct 2003 08:21:30 +1000, Mike Harding
<mike_harding1@nixspamhotmail.com> wrote:

On Thu, 2 Oct 2003 16:36:44 +0200, "Iman Habib"
imanhabibREMOVETHIS@eml.cc> wrote:

Hi guys.

And there's a lot of us! You have probably posted this message
to a couple of million people - maybe more?

Was it really necessary to post to:
alt.engineering.electrical,aus.electronics,sci.electronics.components,sci.electronics.basics,sci.electronics.design
?

Why not try just one group to start with?

Mike Harding

It really puzzles me when people get so bent out of shape at
cross-posting....

ALL the experts don't hang out on a single group.

A *good* news-reader, such as Agent, handles cross-posting with grace,
only showing you the post ONCE.

What's your problem? Using an MShit program as a reader... maybe
Outhouse Excuse?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Rod Speed]

Jim Thompson <invalid@invalid.invalid> wrote in message
news:hehpnvovjujoo0jdc1i52oe7nq9ick4fhv@4ax.com...

Mike Harding <mike_harding1@nixspamhotmail.com> wrote
Iman Habib ><imanhabibREMOVETHIS@eml.cc> wrote

Hi guys.

And there's a lot of us! You have probably posted this
message to a couple of million people - maybe more?

Was it really necessary to post to:
alt.engineering.electrical,aus.electronics,sci.electronics.components,
sci.electronics.basics,sci.electronics.design ?

Why not try just one group to start with?

It really puzzles me when people get
so bent out of shape at cross-posting....

Just the usual mindless ranting about any change.

ALL the experts don't hang out on a single group.

Indeed.

A *good* news-reader, such as Agent, handles cross-posting
with grace,only showing you the post ONCE.

Or automatically marking it as read in all
the groups its posted to when its first read.

What's your problem?

Ear to ear dog shit, basically.

Using an MShit program as a reader... maybe Outhouse Excuse?

It handles cross posting just as elegantly as Agent.

And doesnt turn you into a rabid bigot to boot.;

 

[Mike Harding]

On Thu, 02 Oct 2003 17:46:06 -0700, Jim Thompson
<invalid@invalid.invalid> wrote:

A *good* news-reader, such as Agent, handles cross-posting with grace,
only showing you the post ONCE.

What's your problem? Using an MShit program as a reader... maybe
Outhouse Excuse?

Read the header Jim.

http://www.uwasa.fi/~ts/http/crospost.html

Mike Harding

 

[Rod Speed]

Mike Harding <mike_harding1@nixspamhotmail.com> wrote in
message news:ebvpnv44cqmr12n3s16vs00j3kd71tnr1n@4ax.com...

Jim Thompson <invalid@invalid.invalid> wrote

http://www.uwasa.fi/~ts/http/crospost.html

Nothing in there says that any of the crossposting is inappropriate, fool.

 

[Mike Harding]

On Fri, 3 Oct 2003 15:56:42 +1000, "Rod Speed" <rod_speed@yahoo.com>
wrote:

Mike Harding <mike_harding1@nixspamhotmail.com> wrote in
message news:ebvpnv44cqmr12n3s16vs00j3kd71tnr1n@4ax.com...
Jim Thompson <invalid@invalid.invalid> wrote

http://www.uwasa.fi/~ts/http/crospost.html

Nothing in there says that any of the crossposting is inappropriate, fool.

Illiterate as well as stupid!

Mike Harding

 

[John G]

"Mike Harding" <mike_harding1@nixspamhotmail.com> wrote in message
news:h88qnvo7ihclufpe2ckcutvve1brlnbjpf@4ax.com...

On Fri, 3 Oct 2003 15:56:42 +1000, "Rod Speed" <rod_speed@yahoo.com
wrote:


Mike Harding <mike_harding1@nixspamhotmail.com> wrote in
message news:ebvpnv44cqmr12n3s16vs00j3kd71tnr1n@4ax.com...
Jim Thompson <invalid@invalid.invalid> wrote


Nothing in there says that any of the crossposting is inappropriate,
fool.

Illiterate as well as stupid!

Mike Harding

I do not always agree with Rod and sometimes he is a bit intolerant but

could you please explain what is wrong with "Cross Posting".
It is better than multiple posting and that is explained in YOUR reference
http://www.uwasa.fi/~ts/http/crospost.html

Even Outlook Express handles cross posts quite reasonably.
Wot's Your Real Problem?

--
John G

Wot's Your Real Problem?

 

[Rod Speed]

"Mike Harding" <mike_harding1@nixspamhotmail.com> wrote in message news:h88qnvo7ihclufpe2ckcutvve1brlnbjpf@4ax.com...

On Fri, 3 Oct 2003 15:56:42 +1000, "Rod Speed" <rod_speed@yahoo.com
wrote:


Mike Harding <mike_harding1@nixspamhotmail.com> wrote in
message news:ebvpnv44cqmr12n3s16vs00j3kd71tnr1n@4ax.com...
Jim Thompson <invalid@invalid.invalid> wrote

http://www.uwasa.fi/~ts/http/crospost.html

Nothing in there says that any of the crossposting is inappropriate, fool.

Illiterate as well as stupid!

Even you should be able to bullshit your way out of your
predicament better than that pathetic effort, fuckwit.

 

[default]

(snip)

About the only way I can see you getting useful position information
out of a stationary stepper motor would be by measuring the
inductances of the two sets of coils.

You could do this with very low AC currents, so it wouldn't generate
any torque. You couldn't use particularly high frequencies - the coils
are going to go self-resonant not too far above the maximum stepping
rate, and the iron path losses will become crippling in the same sort
of range - but you should be able to work something out.

There are motor-like parts designed for this sort of job, called
"synchros"

http://www.incon.com/products/prs/1292-ks.htm

shows an example. Analog Devices used to sell integrated circuits
specifically designed for decoding the outputs of these devices, but
I've not had any occasion to check on the status of these parts in
recent years.

-------
Bill Sloman, Nijmegen

You will never get "absolute" position information (turn it on and it
tells you how many degrees the shaft is relative to "north") but it is
easy to get relative information. With my synchro, the position was
very accurately reflected in the drive motor. As long as no one turned
the drive motor deliberately, it would show just what the driven motor
was doing.

There's all kinds of shaft encoders, the simplest is just a series of
lines on a disc to pick up rotational speed, a stepper could easily
handle that task. A stepper just as easily goes one further, it puts
out two phases so it can tell which direction the shaft is turning in.
(or, more correctly, if the direction has changed).

If one is a hobbyist and cost is a consideration, or just fooling
around with an idea, steppers are interesting devices. Where else can
you get an off the shelf alternator that puts out a few watts at slow
rotational speeds, for instance? Priced a full fledged synchro system
recently? Even surplus 400 cycle aircraft synchros aren't used much
these days, shipboard 120/60 cycle ones are practically museum pieces.
I built my stepper synchro for less than $10. Solve a problem
inexpensively and get to tinker with it is how I relax - Working on
someone else's 8 million dollar project and I buy better and more
costly hardware.


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[default]

On 2 Oct 2003 16:27:53 -0700, alantak69@yahoo.com (Alan) wrote:

"Iman Habib" <imanhabibREMOVETHIS@eml.cc> wrote in message news:<blhd5s$c078e$1@ID-168056.news.uni-berlin.de>...
Hi guys.

I've been thinking a bit about steppers as incremental rotary sensor today.

I guess its pretty simple to use them as sensors by just continuously
normalizing the signal and sampling voltage change (looking for highs and/or lows)
But that would only work well if the shaft moved at acceptable speed.
I think that to slow movements would not induce any worthwhile signal.


Even at slow speed as in single step, there is a breakaway function
and snapping to the new position. Don't really expect you could do it
that it couldn't be sensed, short of having a 3 foot long lever on the
shaft so that you could move it VERY slowly accurately against it's
internal magnetic field.

Also, use a high voltage stepper. A 24 V stepper turned will put
something out even if you turn it very slowly. Should be very hard to
get a non-detect.

Alan
You're right. My first attempt was to input the stepper to a

darlington transistor with no amplification - the stepper had to turn
at some speed before the 1.2 volts the darlington needed was met.

Second attempt was to bias the darlington's just shy of conduction -
worked but as ambient temperature increased, the darlingtons would
work in the linear range and self heat.

Third attempt was with an op amp, and it is so sensitive that it is
hard to imagine anything moving so slowly that it wouldn't catch it.
And like you said, the natural cogging action of the stepper will
cause it to jump ahead when the magnetic field between steps is
overcome (assuming there's just a little slop in the linkage between
the turning shaft and the stepper shaft).

Turning it by hand with a knob on the shaft, I couldn't move it so
slowly that the op amp wouldn't detect it. Geological events might
move slowly enough that a stepper won't detect them - for that we have
lasers and mirrors.


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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[Michael Black]

Mike Harding (mike_harding1@nixspamhotmail.com) writes:

On Thu, 02 Oct 2003 17:46:06 -0700, Jim Thompson
invalid@invalid.invalid> wrote:

A *good* news-reader, such as Agent, handles cross-posting with grace,
only showing you the post ONCE.

What's your problem? Using an MShit program as a reader... maybe
Outhouse Excuse?

Read the header Jim.

http://www.uwasa.fi/~ts/http/crospost.html

Mike Harding

It's not just a matter of newsreaders. Cross-posting is usually the

result of someone who can't be bothered to figure out the most appropriate
newsgroup, so they shotgun across a bunch of somewhat related ones:
alt.engineering.electrical,
aus.electronics,
sci.electronics.components,
sci.electronics.basics,
sci.electronics.design

I can say outright that if it's posted to basics, it doesn't belong
in design, or vice versa. If you are a beginner, then you aren't ready
for design, and if you can design, then you've gone past the basics.

And then, let's post to a two other hierarchies, just because they exist.
While I can see someone post to the Australian newsgroup, because they live
there and are among familiar people, I don't see the point if they are posting
to some other newsgroup. And if the original poster is not in Australia,
then the only reason they've posted there is because they saw the "electronic"
in the newsgroup name and decided to post there. That happens a lot with
cross-posting, people search for pertinent newsgroups using a keyword,
and then don't bother checking the newsgroups before they post.

And while I have no idea what alt.engineering.electrical is supposed to
be for, electrical invokes an image of motors and light switches and
things that Tesla, Edison, and Westinghouse worked with. A stepper is
nominally an electrical rather than electronic item, but I'd unless someone
is discussing making stepper motors, I'd place them in the electronic realm
since they virtually all the time require

Another key point against cross-posting is that it can often result
in unrelated issues, such as this, because someone has jumped into
some existing groups at the same time. People who don't normally talk
together are suddenly interacting, but without the interaction of
other things to temper the discussion. So if a discussion is kept to
one newsgroup, if someone says something that I'd consider outrageous,
I might think twice about saying something because I know some common
points that I have with that poster, and maybe even I realize that
I'll have to live with that person in the newsgroup in the future.
That's not the case when suddenly "people from other newsgroups" are
in the familiar newsgroup. This guy is an idiot for cross-posting.
The only real thing I know about him is that he's cross-posted; I
don't even know which, if any, of the newsgroups he posted to
is the one he regularly hangs out in.

Michael

 

[default]

On 3 Oct 2003 15:46:51 GMT, et472@FreeNet.Carleton.CA (Michael Black)
wrote:

Mike Harding (mike_harding1@nixspamhotmail.com) writes:
On Thu, 02 Oct 2003 17:46:06 -0700, Jim Thompson
invalid@invalid.invalid> wrote:

A *good* news-reader, such as Agent, handles cross-posting with grace,
only showing you the post ONCE.

What's your problem? Using an MShit program as a reader... maybe
Outhouse Excuse?

Read the header Jim.

http://www.uwasa.fi/~ts/http/crospost.html

Mike Harding

It's not just a matter of newsreaders. Cross-posting is usually the
result of someone who can't be bothered to figure out the most appropriate
newsgroup, so they shotgun across a bunch of somewhat related ones:
alt.engineering.electrical,
aus.electronics,
sci.electronics.components,
sci.electronics.basics,
sci.electronics.design

I can say outright that if it's posted to basics, it doesn't belong
in design, or vice versa. If you are a beginner, then you aren't ready
for design, and if you can design, then you've gone past the basics.

And then, let's post to a two other hierarchies, just because they exist.
While I can see someone post to the Australian newsgroup, because they live
there and are among familiar people, I don't see the point if they are posting
to some other newsgroup. And if the original poster is not in Australia,
then the only reason they've posted there is because they saw the "electronic"
in the newsgroup name and decided to post there. That happens a lot with
cross-posting, people search for pertinent newsgroups using a keyword,
and then don't bother checking the newsgroups before they post.

And while I have no idea what alt.engineering.electrical is supposed to
be for, electrical invokes an image of motors and light switches and
things that Tesla, Edison, and Westinghouse worked with. A stepper is
nominally an electrical rather than electronic item, but I'd unless someone
is discussing making stepper motors, I'd place them in the electronic realm
since they virtually all the time require

Another key point against cross-posting is that it can often result
in unrelated issues, such as this, because someone has jumped into
some existing groups at the same time. People who don't normally talk
together are suddenly interacting, but without the interaction of
other things to temper the discussion. So if a discussion is kept to
one newsgroup, if someone says something that I'd consider outrageous,
I might think twice about saying something because I know some common
points that I have with that poster, and maybe even I realize that
I'll have to live with that person in the newsgroup in the future.
That's not the case when suddenly "people from other newsgroups" are
in the familiar newsgroup. This guy is an idiot for cross-posting.
The only real thing I know about him is that he's cross-posted; I
don't even know which, if any, of the newsgroups he posted to
is the one he regularly hangs out in.

Michael
Hi Mike

How do you feel about off topic rants posted to five newsgroups?

Just joking . . .


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[daestrom]

"Rod Speed" <rod_speed@yahoo.com> wrote in message
news:blj32r$cm6vc$1@ID-69072.news.uni-berlin.de...

Mike Harding <mike_harding1@nixspamhotmail.com> wrote in
message news:ebvpnv44cqmr12n3s16vs00j3kd71tnr1n@4ax.com...
Jim Thompson <invalid@invalid.invalid> wrote

http://www.uwasa.fi/~ts/http/crospost.html

Nothing in there says that any of the crossposting is inappropriate, fool.

Well, it does mention that 'should never be used indiscrimenately.' and
'Avoid cross-posting to groups that are branches of the same sub-hierarchy,
that is don't cross-post to adjacent newsgroups.' Like, oh, maybe
'sci.electronics.components, sci.electronics.basics, and
sci.electronics.design.'

But as cross-posts go, this thread is pretty 'nice'. It started
electrical/electronic in nature and is limited to groups that have that
frame of mind.

The really nasty ones are political posts to science and engineering groups
like the recent rash of them by 'Your Special Friend' and his related names.
Or the obvious virus trolls and porno spam. But hey, I'm a big boy, I can
ignore them. Even with MS Outlook Express, it isn't very hard to do.

daestrom

 

[Rod Speed]

daestrom <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote
in message news:bKhfb.10890$LI.4452@twister.nyroc.rr.com...

Rod Speed <rod_speed@yahoo.com> wrote
Mike Harding <mike_harding1@nixspamhotmail.com> wrote
Jim Thompson <invalid@invalid.invalid> wrote

http://www.uwasa.fi/~ts/http/crospost.html

Nothing in there says that any of the crossposting is inappropriate, fool.

Well, it does mention that 'should never be used indiscrimenately.'

Yes, but that clearly wasnt done with the original post.

and 'Avoid cross-posting to groups that are branches of the same
sub-hierarchy, that is don't cross-post to adjacent newsgroups.'

Thats a stupid proscription.

Like, oh, maybe 'sci.electronics.components,
sci.electronics.basics, and sci.electronics.design.'

But as cross-posts go, this thread is pretty 'nice'.

Yep, it clearly is doing what that FAQ recommends.

It started electrical/electronic in nature and is
limited to groups that have that frame of mind.

Precisely.

The really nasty ones are political posts to science and engineering groups
like the recent rash of them by 'Your Special Friend' and his related names.
Or the obvious virus trolls and porno spam. But hey, I'm a big boy, I can
ignore them. Even with MS Outlook Express, it isn't very hard to do.

Completely trivial, actually.

 

[Rod Speed]

Michael Black <et472@FreeNet.Carleton.CA> wrote
in message news:blk5lb$41u$1@freenet9.carleton.ca...

Mike Harding (mike_harding1@nixspamhotmail.com) writes
Jim Thompson <invalid@invalid.invalid> wrote

A *good* news-reader, such as Agent, handles cross-posting
with grace, only showing you the post ONCE.

What's your problem? Using an MShit program as a reader...
maybe Outhouse Excuse?

Read the header Jim.

http://www.uwasa.fi/~ts/http/crospost.html

It's not just a matter of newsreaders.

Correct. There aint many used much that dont handle them gracefully
and the fools that are using ones that dont handle crossposting
gracefully dont get to stop on crossposting because their pathetic
excuse for a newsreader doesnt handle crossposting gracefully.

Cross-posting is usually the result of someone who can't
be bothered to figure out the most appropriate newsgroup,

Bullshit. Cross posting like was seen with the post being discussed
is done because there isnt a single appropriate newsgroup and it
makes a lot more sense to crosspost it to those that are appropriate
rather than posting to just one of them and see what replys turn up.

so they shotgun across a bunch of somewhat related ones:
alt.engineering.electrical,
aus.electronics,
sci.electronics.components,
sci.electronics.basics,
sci.electronics.design

Every single one is entirely appropriate to the question being asked.

I can say outright that if it's posted to basics,
it doesn't belong in design, or vice versa.

Mindless hair splitting. It is a pretty basic question, whether
a stepper motor is usable as a rotational position sensor.
And its appropriate in design too incase there are some
rather subtle factors involved, as there are in this case.

If you are a beginner, then you aren't ready for design,

Bullshit. And basics aint necessarily just beginners anyway.
Many get into engineering because they want to make
something that isnt readily buyable and they may well not
have enough of a theoretical background to allow them to
actually comprehend an answer from someone who replys
assuming that full design is being asked about rather than
just a bit of a rough and ready approach to a problem.

and if you can design, then you've gone past the basics.

Not necessarily.

And then, let's post to a two other hierarchies, just because they exist.

Or you do have a clue and have noticed that the alt heirarchy
exists separately to the more formal hierarchys which attempt
finer distinctions in the structures and that has its own real
downsides, like that question you just split hairs about.

While I can see someone post to the Australian newsgroup,
because they live there and are among familiar people, I don't
see the point if they are posting to some other newsgroup.

Your problem. Thats done because the geographic group may
well not have too many who have gotten involved in that subject.

And if the original poster is not in Australia, then the
only reason they've posted there is because they saw the
"electronic" in the newsgroup name and decided to post there.

Wrong again. You do see quite a few who have noticed that
a particular geographic group has managed to achieve some
regular posters who do make useful contributions and some
choose to post to them just because they have noticed that.

That happens a lot with cross-posting, people search
for pertinent newsgroups using a keyword, and then
don't bother checking the newsgroups before they post.

Or they have the sense to realise that if there is just one
geographical newsgroup that includes the keyword thats
appropriate, that that may be because for whatever
reason there happens to be collection of individuals
who are interest in that subject who do use usenet.

And while I have no idea what alt.engineering.electrical is supposed
to be for, electrical invokes an image of motors and light switches
and things that Tesla, Edison, and Westinghouse worked with.

Or it could just be a result of the fact that the alt groups arent
named by some committee of self important prats and that
you do get some real downsides like that with that approach.

A stepper is nominally an electrical rather than electronic item,

But they do mostly get discussed in the electronics groups.

but I'd unless someone is discussing making
stepper motors, I'd place them in the electronic
realm since they virtually all the time require

What matters is where they are discussed.

Another key point against cross-posting is that it can often
result in unrelated issues, such as this, because someone
has jumped into some existing groups at the same time.

Hardly the end of civilisation as we know it any time soon.

People who don't normally talk together are
suddenly interacting, but without the interaction
of other things to temper the discussion.

Again, hardly the end of civilisation as we know it any time soon.

So if a discussion is kept to one newsgroup, if someone says
something that I'd consider outrageous, I might think twice
about saying something because I know some common points
that I have with that poster, and maybe even I realize that
I'll have to live with that person in the newsgroup in the future.

You're always welcome to do that sort of thing if you like.
No one is ever welcome to attempt to ram their views on
how things must be done down others throats like Mike did.

That's not the case when suddenly "people from other newsgroups"
are in the familiar newsgroup. This guy is an idiot for cross-posting.

You are an idiot for not understanding how effective cross posting can be.

The only real thing I know about him is that he's cross-posted;

Thats the nature of usenet, stupid.

I don't even know which, if any, of the newsgroups
he posted to is the one he regularly hangs out in.

Its completely trivial for anyone with a clue to check that.

You cant manage it ? Your problem.