Capacitor/Condenser Microphones

[Martin]

Am 7 Nov 2004 07:18:36 -0800 schrieb Tim Shoppa <shoppa@trailing-edge.com>:

Jim Thompson <thegreatone@example.com> wrote in message
news:<1kaqo05rurt5015riodfvvia57s7tdvpna@4ax.com>...
Didn't some old capacitor/condenser microphones use RF oscillation?

You know, every time I build a VHF oscillator I end up with so much in
the way of microphonics that I wish someone had hired me to build a
microphone instead

I know this the other way round: every time I try to build an RF

Amplifier, its has much more stable VHF,UHF or even GHz oszillation than
if I had to build an oscillator.

--
Martin

 

[Terry Given]

Martin wrote:

Am 7 Nov 2004 07:18:36 -0800 schrieb Tim Shoppa <shoppa@trailing-edge.com>:

Jim Thompson <thegreatone@example.com> wrote in message
news:<1kaqo05rurt5015riodfvvia57s7tdvpna@4ax.com>...

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


You know, every time I build a VHF oscillator I end up with so much in
the way of microphonics that I wish someone had hired me to build a
microphone instead

I know this the other way round: every time I try to build an RF
Amplifier, its has much more stable VHF,UHF or even GHz oszillation
than if I had to build an oscillator.

Sods Law: Oscillators dont, amplifiers do

Cheers
Terry

 

[Richard Crowley]

"Joerg" wrote

Now I just have to find out why sometimes a post never shows up. Or even
more weird, if a question is posted in
two NGs my answer shows up in one but not in the other even though both
NGs were in the adressee list before sending.

It happened to me just last week. A post of mine never showed
up on Supernews, but responses to it did. And the post showed
up on our NNTP server at the office and on the Google archive.

NNTP (Usenet newsgroups) is *not* a guaranteed messaging
protocol like SNMP (email). It is a best-effort, store-&-forward,
peer-to-peer mechanism and likely works better now with The
Internet as a transport infrastructure than it did back in the early
days of DARPAnet, etc.

 

[Allan Herriman]

On Sat, 06 Nov 2004 19:59:38 GMT, donaldun@spamfreepearce.uk.com (Don
Pearce) wrote:

On Sat, 06 Nov 2004 12:50:27 -0700, Jim Thompson
thegreatone@example.com> 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 make RF-based microphones. The MKH range is what you want.

I used an MKH816-TU3 once. IIRC, it had an 8MHz oscillator and used a
12V phantom supply. The glossy brochure said that it had two
advantages over the more conventional high voltage bias:

1. No noise due to DC leakage in transducer.

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.

Regards,
Allan

 

[Watson A.Name - \"Watt Su]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:lnxjd.18902$6q2.3144@newssvr14.news.prodigy.com...

Hi Graham,

In Netscape - which I still prefer to browse ngs. Click on 'cancel
message'


I use Mozilla because it doesn't freeze up on me. Although it is
closely
related to Netscape it does not have a cancel feature. When I searched
the help routine for it, it also came up with a blank.

Under Message, the Delete message is grayed out. Have you tried that?

Regards, Joerg

http://www.analogconsultants.com

 

[Watson A.Name - \"Watt Su]

"Terry Given" <my_name@ieee.org> wrote in message
news:5sxjd.4863$op3.184034@news.xtra.co.nz...

Martin wrote:

Am 7 Nov 2004 07:18:36 -0800 schrieb Tim Shoppa
shoppa@trailing-edge.com>:

Jim Thompson <thegreatone@example.com> wrote in message
news:<1kaqo05rurt5015riodfvvia57s7tdvpna@4ax.com>...

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


You know, every time I build a VHF oscillator I end up with so much
in
the way of microphonics that I wish someone had hired me to build a
microphone instead

I know this the other way round: every time I try to build an RF
Amplifier, its has much more stable VHF,UHF or even GHz oszillation
than if I had to build an oscillator.


Sods Law: Oscillators dont, amplifiers do

I thought that was Barkhausen..

Anyway, that's been my experience, also.

Cheers
Terry

 

[Allan Herriman]

On Sat, 06 Nov 2004 12:50:27 -0700, Jim Thompson
<thegreatone@example.com> 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?

Schematics:

http://www.waltzingbear.com/Schematics/Sennheiser.html


Regards,
Allan

 

[Allan Herriman]

On Mon, 08 Nov 2004 18:30:55 +1100, Allan Herriman
<allan.herriman.hates.spam@ctam.com.au.invalid> wrote:

On Sat, 06 Nov 2004 19:59:38 GMT, donaldun@spamfreepearce.uk.com (Don
Pearce) wrote:

On Sat, 06 Nov 2004 12:50:27 -0700, Jim Thompson
thegreatone@example.com> 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 make RF-based microphones. The MKH range is what you want.

I used an MKH816-TU3 once. IIRC, it had an 8MHz oscillator and used a
12V phantom supply. The glossy brochure said that it had two
advantages over the more conventional high voltage bias:

1. No noise due to DC leakage in transducer.

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.

Regards,
Allan

 

[Joerg]

Hi Watson A.Name,

Under Message, the Delete message is grayed out. Have you tried that?


I am using Mozilla 1.6 and there is no 'delete' field under the message

menu. No grayed out one either.

Regards, Joerg

http://www.analogconsultants.com

 

[Watson A.Name - \"Watt Su]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:6ORjd.39812$QJ3.17615@newssvr21.news.prodigy.com...

Hi Watson A.Name,

Under Message, the Delete message is grayed out. Have you tried
that?


I am using Mozilla 1.6 and there is no 'delete' field under the
message
menu. No grayed out one either.

Regards, Joerg

Odd. Anyway, you should go to the newer version. IIRC they corrected a
vulnerability that was in earlier (1.6 or earlier) versions.

 

[Mark Zenier]

In article <10otjuvcdjbc8c0@corp.supernews.com>,
Richard Crowley <rcrowley7@xprt.net> wrote:

"Joerg" wrote
Now I just have to find out why sometimes a post never shows up. Or even
more weird, if a question is posted in
two NGs my answer shows up in one but not in the other even though both
NGs were in the adressee list before sending.

It happened to me just last week. A post of mine never showed
up on Supernews, but responses to it did. And the post showed
up on our NNTP server at the office and on the Google archive.

NNTP (Usenet newsgroups) is *not* a guaranteed messaging
protocol like SNMP (email). It is a best-effort, store-&-forward,
peer-to-peer mechanism and likely works better now with The
Internet as a transport infrastructure than it did back in the early
days of DARPAnet, etc.

Actually, Usenet didn't use the Internet for the first 5 years or so,
rather, the main transport was an ad hoc network of systems using UUCP
dial up telephone transport, and that persisted for another 5-7 years
after NNTP came into existence (around 1986), until real Internet access
became afordable and the traffic rose to the point when a modem couldn't
cope with it any longer. For quite a while, Usenet was transported as
batches thru a wide variety of networks, and even airfreighted magnetic
tape.

The ARPANET used mailing lists instead, some of them gatewayed
to the equivalent newsgroup. (Yea, it was ARPANET back then. Things
military were not tolerated as much as today).

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

 

[Tim Williams]

"Chuck Harris" <cf-NO-SPAM-harris@erols.com> wrote in message
news:5PqdnQDYetBjrwzcRVn-qA@rcn.net...

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.

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

Tim

--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms

 

[Richard Crowley]

"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.

 

[Pooh Bear]

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.

Indeed !

You need to be quick about it.

Some news servers don't allow message cancelling anyway. Google for
example IIRC.


Graham

 

[Joerg]

Hi Richard,

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.

That is what I thought. Once it propagated it seems to be too late. Not
that I ever wanted to cancel a post but thanks to all you guys for
explaining. I simply did not know that one can do that.

Now I just have to find out why sometimes a post never shows up. Or even
more weird, if a question is posted in two NGs my answer shows up in one
but not in the other eventhough both NGs were in the adressee list
before sending.

Regards, Joerg

http://www.analogconsultants.com

 

[Watson A.Name - \"Watt Su]

"Tim Williams" <tmoranwms@charter.net> wrote in message
news:10oqoih8ube6h70@corp.supernews.com...

"Rich The Philosophizer" <null@example.net> wrote in message
newsan.2004.11.06.21.11.39.691170@neodruid.org...
OK, lessee-

Not only that but most servers don't honor the cancellation either,
something known as Dave the Resurrector I recall...

I believe the D (Dave) version was superseded by the G version a few
years ago. I don't know what version it's on now. Thanks to Hipcrime.

:-(

But I think the resurrector is for rogue cancellations, not for
cancellations from the originator. So it may not prevent you from
cancelling your own posts. But I think AOL is one of the major usenet
servers that doesn't honor cancels. But that's from what I knew about
it several years ago.

Tim

--

 

[Joerg]

Hi Graham,

In Netscape - which I still prefer to browse ngs. Click on 'cancel
message'


I use Mozilla because it doesn't freeze up on me. Although it is closely

related to Netscape it does not have a cancel feature. When I searched
the help routine for it, it also came up with a blank.

Regards, Joerg

http://www.analogconsultants.com

 

[Rich The Philosophizer]

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-

 

[Jim Thompson]

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

Whuffo you doing this?

If it's of interest QST ran a couple of articles a while back on home
brewing your own condenser mics, but they use HV DC and FET preamps to
extract the signal. Pretty clever -- the author was claiming high audio
quality from aluminum foil and other household items, but then it always
sounds better when you do it yourself...

Think micro-microphones ;-)

...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.

 

[Watson A.Name - \"Watt Su]

"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

Whuffo you doing this?

If it's of interest QST ran a couple of articles a while back on home
brewing your own condenser mics, but they use HV DC and FET preamps
to
extract the signal. Pretty clever -- the author was claiming high
audio
quality from aluminum foil and other household items, but then it
always
sounds better when you do it yourself...

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?