Ultrasonic

[Korben Dallas]

Hello,

I am requesting help to construct an ultrasonic device that emits sound at
about 25Khz. Unlike most ultrasonic devices, I want the device to carry
sound over 100 feet (or 30 meters) and still be over 140 decibels at 100
feet (or 30 meters).

Does anyone know how I can do this? Plans? Actual devices? Please reply.



All I know of this is that the sirens on fire engines can do this for miles.

 

[Vidar Lřkken]

Korben Dallas wrote:
[...]
Hey, noone in here likes multiposting. Please cross-post for the future.


--
MVH,
Vidar

www.bitsex.net

 

[Korben Dallas]

I've always heard it was the other way around. Are you sure?

That's why I multi'd instead of cross-posted.


"Vidar Lřkken" <njus@vidarlo.net> wrote in message
newsLf5e.4789$4c.617290@juliett.dax.net...

Korben Dallas wrote:
[...]
Hey, noone in here likes multiposting. Please cross-post for the future.


--
MVH,
Vidar

www.bitsex.net

 

[John Miller]

Korben Dallas wrote:

I've always heard it was the other way around. Are you sure?

The courtesy advantage to cross-posting is that people subscribed to
multiple groups will only have to read a message once (provided they
have a competent newsreader).

--
John Miller
email domain: n4vu.com; username: jsm(@)

 

[Michael Black]

"Korben Dallas" (no@spam.com) writes:

I've always heard it was the other way around. Are you sure?

That's why I multi'd instead of cross-posted.


NO, you are misreading.

There is little good to cross-posting. Rare is the time when it
really fits the posting, and you either clutter up the newsgroups
with people who have seen it in another one, or you post to disparate
newsgroups that result in an awful lot of junk because different
newsgroups are responding to people not in the group.

Take note that up till ten years ago, has it really been that long?,
there was only sci.electronics and sci.electronics.repair Dividing
the former up was campaigned for, and voted on successfully, resulting
in the multiple sub newsgroups we see today. This was to subdivide
the discussions, and there's no point in that if people are cross-posting
on a routine basis.

But as bad as cross-posting is, multi-posting is even worse. Suddenly
you are using up more resource, since the messages take up space for
each newsgroup you post it to. And you get multiple threads going,
and surely many of the participants have seen it already in another
newsgroup. Any benefit, as dubious as there is a benefit to cross-posting,
of cross-posting is lost, since you do not get the multi-discipline
that would be the point of cross-posting.

Cross-posting is usually laziness, with the poster unwilling to figure
out the most appropriate newsgroup. This is reinforced with multiple
posting, because it shows off the shotgun approach to posting; hit
enough of them and you'll get an answer. You aren't interested in
hearing the interaction of different groups, you want an answer
and figure you'll get one the more newsgroups you hit.

Multiple posting should never happen. Cross-posting should happen rarely.
Nobody should default to cross-posting (though there are people like that)
and one should think very carefully before doing so.

If one isn't sure of the best newsgroup, they should be reading that newsgroup
for a bit to see if it fits. And if it turns out to be the wrong newsgroup,
one can always ask somewhere else later. (Note that's not the same thing
as posting to different newsgroups at the same time with the same message.)

Read Mark Zenier's guide to the hierarchy at:
ftp://ftp.eskimo.com/u/m/mzenier/seguide9706.txt

Michael

"Vidar Lřkken" <njus@vidarlo.net> wrote in message
newsLf5e.4789$4c.617290@juliett.dax.net...
Korben Dallas wrote:
[...]
Hey, noone in here likes multiposting. Please cross-post for the future.


--
MVH,
Vidar

www.bitsex.net

 

[Don Bruder]

In article <d347nc$prh$1@theodyn.ncf.ca>,
et472@FreeNet.Carleton.CA (Michael Black) wrote:

There is little good to cross-posting. Rare is the time when it
really fits the posting, and you either clutter up the newsgroups
with people who have seen it in another one,

And if they're reading the groups using any reasonably modern news
client, that argument is utterly meaningless, since most (if not all) of
such readers automatically deal with "Oh - You already saw that message
and marked it as read over on alt.some.group. No need to show it again
when you click over to alt.some.other.group where it was cross-posted."

Take note that up till ten years ago, has it really been that long?,
there was only sci.electronics and sci.electronics.repair Dividing
the former up was campaigned for, and voted on successfully, resulting
in the multiple sub newsgroups we see today. This was to subdivide
the discussions, and there's no point in that if people are cross-posting
on a routine basis.

It's rare indeed when a single newsgroup can be said to be "The One True
Place" for a particular discussion. Like a face-to-face conversation,
the discussions grow and change, moving away from the topic of the
newsgroup, and back to it, and away again, as time goes by. It's the
nature of the beast. You wouldn't start a real life conversation
about... Oh, let's say horses and horsemanship for an example... in one
room, but then stop everything dead in its tracks and move everybody
involved in it to another room before continuing because something in
the conversation brought electronic stopwatches and their use or repair
into the picture, would you? Likewise, I'm not going to stop the
conversation that got going in rec.equestrian and not continue unless it
gets moved to sci.electronics.stopwatches.repair just because my
horse-based thread forked off a sub-conversation on changing the
batteries in the stopwatch I use for timing my run through a
horse-jumping course.

On the other hand, if the conversation is clearly migrating from the
realm of horses to pure stopwatch repair, then it makes sense to move
the conversation from that point into sci.electronics.stopwatches.repair.

But as bad as cross-posting is, multi-posting is even worse. Suddenly
you are using up more resource, since the messages take up space for
each newsgroup you post it to.

On this point, we agree - Multi-posting is usually, if not always, bad
form, a waste of effort, and a resource hog.

Cross-posting is usually laziness, with the poster unwilling to figure
out the most appropriate newsgroup. This is reinforced with multiple
posting, because it shows off the shotgun approach to posting; hit
enough of them and you'll get an answer. You aren't interested in
hearing the interaction of different groups, you want an answer
and figure you'll get one the more newsgroups you hit.

You say this as though it were a bad thing...

Dunno about anyone else, but I could care less about "interaction of
different groups" when I need an answer - I want the answer, and if I'm
turning to a usenet group to find it, I probably need it as quickly as I
can get it after not being able to find it by other methods. Likewise, I
probably have no interest in "interaction of different groups" - only
the answer to my question. So if I can't find it for myself via other
methods, I "shotgun" the question to a small handful of groups that seem
to be most relevant to the subject of the question in hopes of stumbling
across the person who has the answer and will post it in reply.
Unfortuately, that's about the best that can be done, since a
specialized topic frequently has either no "proper" group for the
question to be asked in at all, or if such a "proper" group exists, it's
frequently low-to-no traffic due to being so specialized.

A real-world exmple: A few weeks ago, I needed a torque specification
for a bolt on my car. There *IS NO* newsgroup that's specific to my car.
Google gave me way too much irrelevant cruft to even try to wade
through. Lycos gave me nothing. Other web searches came up similarly
empty. So I posted my question, crossing it to about 4 different
automotive groups, and had the exact answer I needed about 10 mintues
later when someone who knew the answer hit my posting in one of those
groups. Which group did he see it on? I don't know. And I don't care.
But he saw it, and was able to give me (and anyone else who might have
been interested) the answer.

Care to tell me what the most appropriate newsgroup would be for my
question?

OK, now that you've said it's "some.car.repair.group", what about the
fact that none of the three separate news servers (all quite good, but
none of them being of the "We carry every group that's ever been
newgrouped since the beginning of Usenet" persuasion) my ISP provides
access to carries "some.car.repair.group"? Presumably, under your
"rules", that means I'm not permitted to post my question at all, since
I have no access to what you have determined is "The One Right Group"?

Multiple posting should never happen. Cross-posting should happen rarely.
Nobody should default to cross-posting (though there are people like that)
and one should think very carefully before doing so.

Dude, you need the mental equivalent of a good sized bowl of bran flakes.

Whoops, sorry... Guess I should have taken this post over to
alt.jeeze.some.people.are.anal in order to keep things properly
segregated, eh?

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[Fester Addams]

top-posting, cross-posting, multi-posting...

Poor Korben got his thread hijacked by a bunch of Nazis. Get a life outside
Usenet you damned Nazis!


FA

 

[JeffM]

Korben Dallas top-posted:

I've always heard it was the other way around. Are you sure?
That's why I multi'd instead of cross-posted.

Vidar Lřkken wrote:
Hey, noone in here likes multiposting. Please cross-post for the
future.

Here are your 2 parallel threads:
http://groups-beta.google.com/group/sci.electronics.basics/browse_frm/thread/6cdb721b40bd349e
http://groups-beta.google.com/group/sci.electronics.misc/browse_frm/thread/6e5820605839297a

No one is 1 thread
has any idea what someone responding to the other thread has said.
They can't correct errors
and they can't tell when the question has been properly answered.


You also need to get a handle on not top-posting.