Replace the MEMS microphone

Hello. If th microphone of the Audiomoth 1.0.0 and 1.1.0 is obsolete and we can't buy it.

We can fix the Audiomoth 1.0 Whit the microphone SPU0410LR5H, the same as the Audiomoth 1.2, if we found someone who knows the soldering method, of course.

Thank you very much.

Daniel

Hi Robert, AudioMoth 1.0.0 and 1.1.0 use the SPM0408LE5H - datasheet here.

However, since the launch of AudioMoth this microphone has stopped manufacture so AudioMoth 1.2.0 uses the SPU0410LR5H - datasheet here. The latter has much lower internal gain so the AudioMoth 1.2.0 has an external pre-amplifier to bring the output up to the same level.

Alex

Hi Alex, I was wondering whether the Audiomoth v.1.2.0 keeps working with the SPM0408LE5H-TB-6 from the v1.1.0 or you installed a different one. Thank you,

Robert

Hi, The microphone is a Knowles SPM0408LE5H-TB-6 -

https://www.digikey.co.uk/product-detail/en/knowles/SPM0408LE5H-TB-6/423-1129-2-ND/1992875

The full parts list is here -

https://circuithub.com/projects/OpenAcoustics/AudioMoth/revisions/11676.

As Justin says replacing the microphone is a bit tricky - you'll need to find someone with a hot-air rework station - https://learn.sparkfun.com/tutorials/how-to-use-a-hot-air-rework-station/all. With the hot-air station it's quite straightforward with some experience - just heat up the existing one - remove it with tweezers - place the new one in position and heat up the existing solder until it reflows again.

The microphone, as I recall, is a Knowles SPM0410 but it is a surface mount device that has numerous pads un the underside which have been reflow soldered to the board, so that removal would be very difficult and replacement in situ almost impossible. Such things can be done but the techniques are difficult to acquire and the equipment would probably cost more than the AudioMoth. A better approach would be to cut the tracks to the microphone (circuit diagrams and board layout are available on here somewhere) and use fine wire-wrap type wire to connect them to a 3.5m jack socket. With a bit of care it is then possible to mount a replacement microphone in the shell of a metal 3.5mm jack plug. Use a small 0.1uF capacitor to connect the microphone signal to the tip, use the ring to provide a 3V (or 5V through a 10k resistor on the AudioMoth board) to provide power for the microphone, with another small tantalum capacitor to ground for decoupling. This provides a useful style of mounted microphone that will plug into any stereo microphone input jack that provides bias voltage as well as into the newly mounted AudioMoth jack. If you are not interested in the ultrasonics other Knowles microphones can be used which are a bit simpler to attach wires to.