Audio amplifier for condenser mic

- D. Prabakaran

This is a low cost condenser mic amplifier that provides amplified audio output of 0.5 watts at 4.5 V supply. The preamplifier portion uses two BC148 transistors that amplifies the weak audio signal output from the condenser mic. The output of the preamplifier is fed to the input of a BEL1895 IC. It is a monolithic audio power amplifier commonly used in AM radios. The output from the power amplifier drives a 4 Ohm speaker through a coupling capacitor C14 (470 uF).

Various Audio Amplifier IC Circuits

Here are some of the popular audio amplifier IC circuits.

Source

Source: http://www.rason.org/Projects/icamps/icamps.htm

6 Watt Audio Amplifier based on TA7222AP IC

This circuit provides audio amplification of approximately 6W. It uses TA7222AP audio amplifier IC that can deliver 6W to a 4 Ohm speaker. This IC has other nice features like muting function, low distortion, high ripple rejection, short circuit protection, thermal shut down etc. This amplifier can be operated from 8 to 12V and this makes it ideal for car radio applications.

Source: http://www.circuitstoday.com/wp-content/uploads/2009/08/6w-amplifier-using-ta7222ap.png

LM386 Based Low Power Audio Amplifier

About LM386

LM386 is a low power audio amplifier IC designed for use in low voltage consumer applications. You can use this 8-pin IC to amplify the output signal from your mp3 player or computer audio output. The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation.

Applications of LM386

• AM-FM radio amplifiers
• Portable cassette player amplifiers
• Intercoms
• TV sound systems
• Line drivers
• Ultrasonic drivers
• Small servo drivers, etc.

The circuit below shows a simple audio amplifier using LM386 with a gain of 200. If the 10uF capacitor connected between pins 1 and 8 is taken off, the gain would be 20.  The gain can be adjusted between 20-200 by placing an appropriate resisor in series with this 10uF capacitor.

Source: http://www.eleccircuit.com/wp-content/uploads/2008/02/simple-lm386-audio-amplifier.jpg