We have a TDK ICS40169 microphone with the following circuitry in operation (see pic, should be like the eval board EV_ICS-40619-FX)
VDD and Ground are supplied by a laboratory power supply.
If we connect the + and - outputs of the microphone to an oscilloscope, we only see a short ripple in VERY loud noises.
We would like to put the microphone signal directly into a MicPream (Behringer ADA8200), but only noise can be measured.
Do we have to add another gain stage or are we otherwise making a mistake? How would be the procedure to record mic signals from the eval board?
Thanks a lot!
Without see the schematics, I will just get a short comment on the problem. First, I will need some quantitative information on how loud the sound source is and what the amplitude is on the voltage output. With that it can be determined if the output is correlate to the acoustic pressure level. Did you buy bare microphones and put them on a board by your assembly house? If so, there is a chance the microphone damaged during the assembly process.
Dear Jin Jiang,
thank you very much for the answer.
The Sound source is a speaker reading sentences at normal loudness with 40cm distance to the microphone.
Yes we bought bare microphones and aseemblied them by ourselves. We will check for possible damage.
Please find the schematic: Is there any possible error? Can we plug the + and - outputs to an XLR cable and put it directly in a mic preamp (Behringer ADA8200)?
Thank you!
Best
Tim
I dont know why my links keep disappearing:
"https://pasteboard.co/IVFN189.png" "PCB Layout"
"https://pasteboard.co/IVFNfRG.png" "Schematic"
maybe important: If we put the sound output of a smartphone (loudspeaker) directly! (and only directly) on the mic, we see the wave form accourding to the sound playing on the oscilloscope
We now got the eval board and connected the + and - directly to the oscilloscope. We observed the same behaviour as described above....
PLEASE it would be nice to get an answer concerning what we do wrong. Do we need another amplification stage after the microfone ouput in order to see something on the oscilloscope?
*Push*
I would be more than happy for an answer
Thank you very much