Bazza writes:

On Tue, 24 Feb 2004 21:36:32 +0000, Glenn Booth
wrote:



But Your mic is semi-condenser type (electret probably) and it need
a small current to work.

Good theory, but it doesn't seem to need power. I tried it with another
machine, and it works straight into the mic input on a SoundBlaster. I'm
not aware that they have any kind of plug-in power, but I could be
wrong. It also works into a minidisc, so at a pinch I guess I could use
the minidisc as a sort-of preamp and run a line out to the PC. What a
kludge though!

Glen. As a general rule (this is where I get my head chopped off), those
little mics are probably electret types and they DO require power.

Yes.

And, yes,
it probably will work with a SB card because those cards will supply phantom
(+5V ? ) supply from the tip/ring.

The standard approachj is to supply +5V through 2.2 kohm resistor
to the ring of the connectors. There can be slight variations of this
scheme on the soundcards (slight different voltage and resistor values etc.).

PC99 standard lists following PC microphone interface details:
Three-conductor 1/8 inch (3.5 mm) tip/ring/sleeve microphone jack
where the mic signal is on the tip, bias is on the ring, and the
sleeve is grounded. This design is optimized for electret microphones
with three-conductor plugs, but will also support dynamic microphones
with two-conductor (ring and sleeve shorted together) plugs. Minimum
AC input impedance between tip and ground: minimum, 4 kOhm;
recommended 10 kOhm. Input voltages of 10.100 mV deliver full-scale
digital input, using software-programmable .20 dB gain for low output
microphones.Bias should be less than 5.5V when no input and at least
2V with 0.8mA load. Minimum bias impedance between bias voltage source
and ring: 2 kOhm. AC-coupled tip to implement analog (external to ADC)
3 dB rolloffs at 60 Hz and 15 kHz. Most sound card inputs require a
minimum signal level of at least 10 millivolts.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/

Hi,

In message , Richard Crowley
writes
"Glenn Booth" wrote ...
Good theory, but it doesn't seem to need power. I tried it
with another machine, and it works straight into the mic
input on a SoundBlaster. I'm not aware that they have any
kind of plug-in power, but I could be wrong.

All the SoundBlaster boards I've ever seen *DO HAVE* the kind
of power this type of microphone requires. More info here...
http://www.epanorama.net/links/pc_so...ml#interfacing

Thanks, I wasn't aware of that. Sounds like this is what I was missing.
I've been actively steering clear of PC sound card microphone inputs
since my first 8 bit sound card, so I'm learning this a little late!
--
Regards,
Glenn Booth

Hi,

In message , Richard Crowley
writes
"Glenn Booth" wrote ...
Good theory, but it doesn't seem to need power. I tried it
with another machine, and it works straight into the mic
input on a SoundBlaster. I'm not aware that they have any
kind of plug-in power, but I could be wrong.

All the SoundBlaster boards I've ever seen *DO HAVE* the kind
of power this type of microphone requires. More info here...
http://www.epanorama.net/links/pc_so...ml#interfacing

Thanks, I wasn't aware of that. Sounds like this is what I was missing.
I've been actively steering clear of PC sound card microphone inputs
since my first 8 bit sound card, so I'm learning this a little late!
--
Regards,
Glenn Booth

Hi,

In message , Richard Crowley
writes
"Glenn Booth" wrote ...
Good theory, but it doesn't seem to need power. I tried it
with another machine, and it works straight into the mic
input on a SoundBlaster. I'm not aware that they have any
kind of plug-in power, but I could be wrong.

All the SoundBlaster boards I've ever seen *DO HAVE* the kind
of power this type of microphone requires. More info here...
http://www.epanorama.net/links/pc_so...ml#interfacing

Thanks, I wasn't aware of that. Sounds like this is what I was missing.
I've been actively steering clear of PC sound card microphone inputs
since my first 8 bit sound card, so I'm learning this a little late!
--
Regards,
Glenn Booth

Hi,

In message , Richard Crowley
writes
"Glenn Booth" wrote ...
Good theory, but it doesn't seem to need power. I tried it
with another machine, and it works straight into the mic
input on a SoundBlaster. I'm not aware that they have any
kind of plug-in power, but I could be wrong.

All the SoundBlaster boards I've ever seen *DO HAVE* the kind
of power this type of microphone requires. More info here...
http://www.epanorama.net/links/pc_so...ml#interfacing

Thanks, I wasn't aware of that. Sounds like this is what I was missing.
I've been actively steering clear of PC sound card microphone inputs
since my first 8 bit sound card, so I'm learning this a little late!
--
Regards,
Glenn Booth

Hi,

In message , Tomi Holger Engdahl
writes
Here are two plans that could be of some use to you
(use fixed width font like courier to view the images)

[Snip of some really cool ASCII line art!]

Thanks, that post says it all :-)

Do not use mixer "phantom power" when using this circuit,
because turnign "phantom power" can damage the microphone.

No worries there. You can tell just by looking that this thing isn't
going to be happy with 'real' phantom power.

I'll dig around for a resistor and build something to power it. Thanks
to all who replied.

--
Regards,
Glenn Booth

Hi,

In message , Tomi Holger Engdahl
writes
Here are two plans that could be of some use to you
(use fixed width font like courier to view the images)

[Snip of some really cool ASCII line art!]

Thanks, that post says it all :-)

Do not use mixer "phantom power" when using this circuit,
because turnign "phantom power" can damage the microphone.

No worries there. You can tell just by looking that this thing isn't
going to be happy with 'real' phantom power.

I'll dig around for a resistor and build something to power it. Thanks
to all who replied.

--
Regards,
Glenn Booth

Hi,

In message , Tomi Holger Engdahl
writes
Here are two plans that could be of some use to you
(use fixed width font like courier to view the images)

[Snip of some really cool ASCII line art!]

Thanks, that post says it all :-)

Do not use mixer "phantom power" when using this circuit,
because turnign "phantom power" can damage the microphone.

No worries there. You can tell just by looking that this thing isn't
going to be happy with 'real' phantom power.

I'll dig around for a resistor and build something to power it. Thanks
to all who replied.

--
Regards,
Glenn Booth

Hi,

In message , Tomi Holger Engdahl
writes
Here are two plans that could be of some use to you
(use fixed width font like courier to view the images)

[Snip of some really cool ASCII line art!]

Thanks, that post says it all :-)

Do not use mixer "phantom power" when using this circuit,
because turnign "phantom power" can damage the microphone.

No worries there. You can tell just by looking that this thing isn't
going to be happy with 'real' phantom power.

I'll dig around for a resistor and build something to power it. Thanks
to all who replied.

--
Regards,
Glenn Booth