|
This is a simple microphone preamplifer
circuit which you can use between your microphone and
stereo amplifier. This circuit amplifier microphone
suitable for use with normal home stereo amplifier
line/CD/aux/tape inputs. This mic preamp can take both
dynamic and electret microphone inputs (preamplifer
provides power foe electret microphone elements). The
idea of this circuit is to keep the design as simple as
possible to be easy to build. That was my goal when I
needed a simple external microphone preamplifer for my
mixer. The performance of the circuit is nothing
superior but can be used with many not so serious
projects.
The circuit is a simple one transistor
amplifier with amplification of about 30-40 dB (depends
on transitor, temperature and voltage). The dynamic mic
input is just a simple one transistor amplifier circuit
with nothing special. Electret microphone input has a
resistor R1 fo feeding current through electret
microphone capsule when it is connected to the electret
microphone input. Electret microphone needs some current
(about 1 mA) flowing through it to operate, because
there is a small amplifier circuit inside the microphone
capsule. This circuit is suitable for all typical cheap
electret campsules which available from any electronic
component shop. Because electret microphones have higher
signal level output, it is quite easy to overdrive the
amplifier when you shout to electret microphone.
The circuit is bet to build to a small
metal box where you have a small 9V battery for powering
it. Battery power and metal box keep noise away |
