Adafruit AGC Electret Microphone Amplifier - MAX9814 Created by lady ada Last updated on 2016-09-14 07:22:39 PM UTC
Guide Contents Guide Contents Overview Assembly Prepare the header strip: Add the breakout board: And Solder! Wiring and Test Wiring Test! Do more! Downloads Datasheets & Files Schematics PCB Dimensional Diagram 3D models © Adafruit Industries https://learn.adafruit.
Overview 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 'loud' sounds will be quieted so they don't overwhelm & 'clip' 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 don't want to have to tweak the amplifier gain all the time.
Each order comes with one assembled and tested board, with electret mic pre-soldered on, and a small piece of header. Specifications: Supply Voltage: 2.7v-5.5v @ 3mA current Output: 2Vpp on 1.25V bias Frequency Response: 20Hz - 20 KHz Programmable Attack and Release Ratio Automatic gain, selectable max from 40dB, 50dB or 60dB Low Input-Referred Noise Density of 30nV/ Low THD: 0.04% (typ) © Adafruit Industries https://learn.adafruit.
Assembly Assembly is really easy, you can use straight or 'right-angle' style headers to attach to the PCB. We'll be using the plain straight headers included The board comes with all surface-mount components pre-soldered. The included header strip can be soldered on for convenient use on a breadboard or with 0.1" connectors. You can also skip this step and solder on wires. © Adafruit Industries https://learn.adafruit.
Prepare the header strip: Cut the strip to length if necessary. It will be easier to solder if you insert it into a breadboard - long pins down. Add the breakout board: Place the breakout board over the pins so that the short pins poke through the breakout pads © Adafruit Industries https://learn.adafruit.
And Solder! Be sure to solder all 5 pins for reliable electrical contact. (For tips on soldering, be sure to check out our Guide to Excellent Soldering (http://adafru.it/aTk)). © Adafruit Industries https://learn.adafruit.
Wiring and Test The microphone amp is thankfully quite simple to get started. No microcontroller or programming required. We suggest wiring it up directly with a battery pack and headphones to start while you get a hang of how the AGC acts and responds. You'll need a 3 or 4 AA/AAA battery pack (http://adafru.it/727)(or some external source of 3-5VDC) - we suggest batteries since they are very electrically-quiet compared to USB or wall power adapters.
microphone amp as much! This is not a good time to use your huge Sennheiser cans. Don't connect to speakers or you will get really horrible feedback effects Wiring Connect the amplifier, battery pack and headphone jack as shown above. For the Microphone amp: GND connects to the battery pack ground - black wire VDD connects to the battery pack positive - red wire Connect the Gain pin to VDD for now - green wire Connect the OUT pin to a 1uF-100uF capacitor (really any value will do).
Connect the Left and Right pins together (the microphone is mono out) to the negative side of the capacitor - yellow wires. Connect the center ground pin to the battery ground - blue wire Test! Now try listening to sounds on the headphones, you should notice a strange 'effect' where you can hear people from further away than your hearing is used to! Try setting the Gain pin to the GND pin to get 10dB more gain.
Downloads Datasheets & Files Datasheet for the MAX9814 (http://adafru.it/d9o) Datasheet for the electret mic capsule (http://adafru.it/aW6) Fritzing object in Adafruit Fritzing library (http://adafru.it/aP3) EagleCAD PCB files in GitHub (http://adafru.it/rpb) Schematics PCB Dimensional Diagram © Adafruit Industries https://learn.adafruit.
3D models Thanks to Aron Rubin! adafruit_mic_agc.pdf http://adafru.it/frD adafruit_mic_agc.skp http://adafru.
