Dual-mode microphone pre-amplifier 2011-12-17

[alec_t]

alec_t submitted a new article:

Dual-Mode Microphone Pre-Amplifier - This is a microphone pre-amp which I designed for use with a SoundBlaster(TM) AWE 64 Value sound c

This is a microphone pre-amp which I designed for use with a SoundBlaster(TM) AWE 64 Value sound card; but it should be suitable for any compatible card or PC audio input which provides a 5 Volt supply (via a 2k2, or thereabouts, built-in current-limiting resistor) at the ring contact of a stereo jack plug inserted into the "Mic In" socket of the card/PC. (N.b. it has only been tested with the AWE 64 card.)

The circuit has the following features :-
(1) It will automatically...

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[audioguru]

On the schematic, the slider of VR1 is not connected so it is a fixed resistor, not a potentiometer.
Audioguru

 

[alec_t]

You're quite right AG. Wrist duly slapped. It's only used as a pre-set resistor, not a true pot. I'll correct the schematic pro tem, but I'm working on a revised version of the amp and will post that in due course (don't hold your breath!)

Alec

 

[alec_t]

On the schematic, the slider of VR1 is not connected so it is a fixed resistor, not a potentiometer.
Audioguru

Now connected!