Capacitor/Condenser Microphones

[Martin]

Am Sat, 6 Nov 2004 22:50:02 -0800 schrieb Watson A.Name - "Watt Sun, the
Dark Remover" <NOSPAM@dslextreme.com>:

Think micro-microphones ;-)

...Jim Thompson
--

Well, the telephone sets that we have at work have an electret mic
element in the body of the set for the speakerphone. It's about 3/16"
diameter and even less in depth. That's pretty small, and I'm sure that
the electrets could be made smaller. How small did you have in mind?

Even in the 80ties you could buy Electret-mics with a diameter of 5mm and

2mm high (calculate it yourself in non metric units, if you want ). I
have been in school these times and bought two of them, because I wanted
to built micro radio transmitters, but I did never complete the project.
Now its already some time that I have read about MEMS silicon-microphones,
that have been built.

--
Martin

 

[normanstrong]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com>
wrote in message news:10orhh9m65hopb4@corp.supernews.com...

"Jim Thompson" <thegreatone@example.com> wrote in message
news:idoqo0hfer97s154v2g2qrabssc805n6jr@4ax.com...
On Sat, 06 Nov 2004 15:42:03 -0800, Tim Wescott
tim@wescottnospamdesign.com> wrote:

Jim Thompson wrote:

Didn't some old capacitor/condenser microphones use RF
oscillation?

I seem to vaguely recall such schemes, but my surfing has come
up
nought.

Does anyone have some links?

Thanks!

...Jim Thompson

Sennheiser makes them; the MKH series is an FM mike. It's the same
scheme that was used in the Weathers phonograph pickup many long years
ago.

Norm Strong

 

[Rich The Philosophizer]

On Sat, 06 Nov 2004 22:44:24 -0800, Watson A.Name - "Watt Sun, the Dark
Remover" wrote:

"Rich The Philosophizer" <null@example.net> wrote in message
newsan.2004.11.06.21.11.39.691170@neodruid.org...
On Sat, 06 Nov 2004 13:56:20 -0800, Richard Crowley wrote:

"Joerg" wrote ...
How can you cancel a post to an unmoderated newsgroup? Just
curious.

Canceling a message (only your own, of course!) is a
fundamental part of Usenet and the NNTP protocol.

How it is implemented is dependent on which news-reader
application you are using. I use MS Outlook Express and the
function is found in the menu bar under "Message". In the
drop-down menu is a selection for "Cancel Message"

Note, however, that because of the speed of the modern
internet infrastructure, your Usenet message may have
already been forwarded to hundreds (thousands?) of news
servers and may have already be read/downloaded by
thousands of readers before the cancel message can go
out and do its thing. Usenet was a "store-n-forward" or
a kind of "peer-to-peer" sharing protocol long before
Napster, et. al. came along. Because of that, cancelling
a message is a rather unreliable exercise.

OK, lessee-

Well, if you tried to cancel this message, then it didn't work,
obviously...

Well, it _did_ disappear off _my_ server.

And it's been archived at google already, so I guess "cancel" is
kinda moot.

Cheers!
Rich

 

[Rich The Philosophizer]

On Mon, 08 Nov 2004 23:18:18 +1100, Allan Herriman wrote:

On Mon, 08 Nov 2004 18:30:55 +1100, Allan Herriman

2. Better linearity, which can be a problem with DC bias if the
change in voltage is a significant fraction of the bias voltage. This
normally isn't a problem with 48V bias, but might be a problem at high
SPL with a lower voltage bias.

From http://members.aol.com/mihartkopf/lexicon.htm

"RF Condenser Microphone A very special way to convert the continuous
change of capacitance in a condenser microphone into a usable electric
signal. Here the microphone capsule is part of the frequency
controlling circuit of an RF oscillator. The change of capacitance
modulates the RF in its frequency and the output of the first stage is
an FM signal as you have in any radio. (RF is about 8 MHz, but it is
carefully shielded - no chance to listen to someone else's mics). The
second stage is just an FM demodulator. The big advantage is that the
capsule impedance is approx. 300 Ohms so there won't be any problems
using such a condenser mic in a very moist environment. The big
disadvantage is the large amount of electronics and the requirement to
shield the RF carefully. RF mics are built by Sennheiser (MKH
series)."


The schematic looks more like fixed frequency drive to me though.

Which schematic?

In the one at
http://www.waltzingbear.com/Schematics/Sennheiser/MKH-105.htm
it is a fixed-freq. osc., and the mic changes the center frequency
of the discriminator!

Cheers!
Rich

 

[Chuck Harris]

Mark Zenier wrote:

Much of Netiquette that seems arbitrary now, (like limiting posting
size, not top posting, including enough of the message to create
^^^^^^^^^^^^

Top posting was the norm back then! This came about because the reader
programs like rn, trn, etc. spooled the text onto your screen (or printer)
from the top down. In order to get to the end of the message you had to page
through the whole message. It was considered rude to force a reader to wade
through all of the included text to get to the bottom where some rude boy
placed his note. (most were using 300 baud, or 1200 baud modems)

-Chuck Harris

context, and no commercial postings) came from that era, as necessities
to keep volume down, allow the thread to make sense (as it took two
or three days to get a reply back and sometimes things got lost) and
satisfy the restriction on non-comercial use that was imposed on groups
that were gatewayed to the ARPANET mail reflectors.

Mark Zenier mzenier@eskimo.com Washington State resident

 

[John Miller]

Chuck Harris wrote:

Top posting was the norm back then! This came about because the reader
programs like rn, trn, etc. spooled the text onto your screen (or printer)
from the top down. In order to get to the end of the message you had to
page
through the whole message. It was considered rude to force a reader to
wade
through all of the included text to get to the bottom where some rude boy
placed his note. (most were using 300 baud, or 1200 baud modems)

Not to be disagreeable, or anything, but what was the norm back then was
more editing of replies than top-posting.

--
John Miller, who wuz there
Formerly {emory,gatech}!n4hgf!n4vu!jsm

 

[Guy Macon]

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on Usenet?

Tim Williams wrote:

And any newsreader I know of starts you at the top of the message,
both reading and writing.

That's to make it easy for us to trim the quoted material before
bottom posting our reply.

"Posting at the top because that's where the cursor
happened to be is like shitting in your pants because
that's where your assholec happened to be."
- Philip Herlihy

Short blurbs like this here following a comment make sense, but
people who quote three, four, nine, 25KB of posts simply have
absolutely no justification (though they still flame the fuck
out of 'ya if you call them on it, go figure).

That is worse than top posting. Which is like saying that
Curly Joe is the Intellectual Stooge.

Here are some references for those who are interested
in improving the quality of their posts to newsgroups:

--------------------------------------------------------

"When thou enter a city, abide by its customs."

Quoting Style in Newsgroup Postings
http://www.xs4all.nl/%7ewijnands/nnq/nquote.html

How do I quote correctly in usenet?
http://www.netmeister.org/news/learn2quote2.html

Common Mistakes in Usenet Postings and How to Avoid Them
http://www.complang.tuwien.ac.at/anton/mail-news-errors.html#quoting

Bottom vs. top posting and quotation style on Usenet
http://www.cs.tut.fi/~jkorpela/usenet/brox.html

Why bottom-posting is better than top-posting
http://www.caliburn.nl/topposting.html

+What do you mean "my reply is upside-down"?
http://www.i-hate-computers.demon.co.uk/quote.html

Put an end to Outlook Express's messy quotes with this automated fix!
http://home.in.tum.de/~jain/software/oe-quotefix/

From (spit!) microsoft:

"When including text from a previous message in the thread,
trim it down to include only text pertinent to your response.
Your response should appear below the quoted information."
- http://www.jsiinc.com/newsgroup_document.htm

"Top posting classically or stereotypically involves no
trimming and of course no contextualizing.of prior posts;
contrasted with contextualized posts, which sequence
questions and responses in order and context, along
with trimming of unnecessary lines.

In this contrast, the top post is disorderly, messy,
and most notably egocentrical, because it leaves all
of the cleaning up and reorganization to the correspondent
context posters and because it inappropriately emphasizes
the importance of whatever the top poster has to say or
ask while mostly disregarding everything anyone else has
been said before. It also expects the next reader to try
to guess at what part of the previous posts the top poster
is referring.and makes it nearly impossible to
contextualize hir own responses." -Mike Easter