Interfacing Microphones with an Arduino

If you’ve been following my blog then you’ll know that I’m a fan of the handy little electret mic breakout boards that combine a mic and a pre-amp so that you can interface these directly with the Arduino’s ADC (analog-to-digital converter) for an easy way to get audio into a project.

However, as much as I like these, they are not ideal for a finished project and I’ve started looking into how I can use regular microphones and plug them into an audio jack on my projects. This would involve building a pre-amp circuit into the project though, since microphones generate a tiny voltage that would not register with an ADC.

As a first step, I purchased one of SparkFun’s opamp breakouts and used this to amplify the output from a PDMIC58 mic (quite the bargain at $9.99) and then feed the output to my project.

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This actually works very well and SparkFun are kind enough to make the schematic available, so it would definitely be possible to incorporate this into my project.

It seems that most mono microphones use a 1/4″ or 1/8″ TRS (Tip, Ring, Shield) jack but there are some differences in how they are wired up, and some microphones require power and some don’t, so it seems challenging at the moment to come up with a general design that will work with a wide range of microphones, and I don’t have access to any other microphones for testing.

For my purposes I may be better off making or buying a separate PCB with an audio jack and the pre-amp circuit and then connect the output to my shield. I definitely have much more to learn about microphones.

 

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