MAX9814 Integrated AGC Audio Sensor
Add an ear to your project with this well-designed electret microphone amplifier with AGC. This fully assembled and tested board comes with a 20-20KHz electret microphone soldered on. For the amplification, we use the Maxim MAX9814 Integrated AGC Audio Sensor, a specialty chip that is designed for amplifying electret microphones in situations where the loudness of the audio isnĂ¢â‚¬â„¢t predictable.
This fancy microphone amplifier module is a step above the rest, with built in automatic gain control. The AGC in the amplifier means that nearby Ă¢â‚¬ËœloudĂ¢â‚¬â„¢ sounds will be quieted so they donĂ¢â‚¬â„¢t overwhelm & Ă¢â‚¬ËœclipĂ¢â‚¬â„¢ the amplifier, and even quiet, far-away sounds will be amplified. This amplifier is great for when you want to record or detect audio in a setting where levels change and you donĂ¢â‚¬â„¢t want to have to tweak the amplifier gain all the time.
The chip at the heart of this amp is the MAX9814 Integrated AGC Audio Sensor, and has a few options you can configure with the breakout. The default Ă¢â‚¬Ëœmax gainĂ¢â‚¬â„¢ is 60dB, but can be set to 40dB or 50dB by jumpering the Gain pin to VCC or ground. You can also change the Attack/Release ratio, from the default 1:4000 to 1:2000 or 1:500. The ouput from the amp is about 2Vpp max on a 1.25V DC bias, so it can be easily used with any Analog/Digital converter that is up to 3.3V input. If you want to pipe it into a Line Input, just use a 1-100uF blocking capacitor in series (100uF sounds best).
We are using this board for Speech Recognition, feeding the output directly to ADC input of ARM Controller for processing.
Applications
- Speech Recognition
- Bluetooth Headsets
- Two-Way Communicators
- High-Quality Portable Recorders
- IP Phones/Telephone Conferencing
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