Circuit to connect "Soundblaster" electret microphone to lin

[Robert Ham]

Hi there,

I have three cheap PC "Soundblaster" electret microphones[0] that I
need connect to a multi-channel sound card. The problem is that the
microphones expect a +5V DC bias from their connection with the sound
card[1]. The multi-channel sound card only has line-level inputs and
doesn't provide power for electret microphones[2]. I need to build
three circuits to a) provide the necessary voltage to the microphones,
and b) amplify the microphone signal.

I have found a circuit that appears to cover both issues[3]. However,
I need some clarification on a couple of things. Firstly, I will not
need the dynamic microphone input. Can I simply remove the dynamic
mic terminals and capacitor C3 from the circuit, or is there more to
it than that?

What I'd like to do is build a single box with three circuits on a
single piece of copper-track board and have it supplied by a single
wall-wart power supply. I'm a little unsure how to adjust the circuit
to accommodate this. How can I supply three such circuits from a
single power supply? From what I recall of my physics lessons, I can
either run them in parallel or serial, the consequences of which are
either a tripling of the power supply voltage (from 9V to 18V) or a
tripling, or possibly 1/3ing of.. something else.. amps? I forget.
Any pointers would be appreciated.

Thanks,

Robert Ham


[0] http://www.ebuyer.com/product/111661
[1] http://www.hobby-hour.com/electronics/computer_microphone.php
[2] http://www.m-audio.com/images/global/manuals/070208_Delta1010_UG_EN01.pdf
[3] http://www.tkk.fi/Misc/Electronics/circuits/micamp.html

 

[Tim Perry]

"Robert Ham" <rah@bash.sh> wrote in message
news:1191335303.770546.236910@w3g2000hsg.googlegroups.com...

Hi there,

I have three cheap PC "Soundblaster" electret microphones[0] that I
need connect to a multi-channel sound card. The problem is that the
microphones expect a +5V DC bias from their connection with the sound
card[1]. The multi-channel sound card only has line-level inputs and
doesn't provide power for electret microphones[2]. I need to build
three circuits to a) provide the necessary voltage to the microphones,
and b) amplify the microphone signal.

I have found a circuit that appears to cover both issues[3]. However,
I need some clarification on a couple of things. Firstly, I will not
need the dynamic microphone input. Can I simply remove the dynamic
mic terminals and capacitor C3 from the circuit, or is there more to
it than that?

Yes, just leave C3 off.

What I'd like to do is build a single box with three circuits on a
single piece of copper-track board and have it supplied by a single
wall-wart power supply. I'm a little unsure how to adjust the circuit
to accommodate this. How can I supply three such circuits from a
single power supply? From what I recall of my physics lessons, I can
either run them in parallel or serial, the consequences of which are
either a tripling of the power supply voltage (from 9V to 18V) or a
tripling, or possibly 1/3ing of.. something else.. amps? I forget.
Any pointers would be appreciated.

parallel is the way to go.

Thanks,

Robert Ham


[0] http://www.ebuyer.com/product/111661
[1] http://www.hobby-hour.com/electronics/computer_microphone.php
[2]
http://www.m-audio.com/images/global/manuals/070208_Delta1010_UG_EN01.pdf
[3] http://www.tkk.fi/Misc/Electronics/circuits/micamp.html

Personally i would use a low cost mixer with direct outs and low cost
dynamic or condensor mics.

I understand you want to use what is on hand at lest cost.