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Hi Edwin I started to work on the preamp but I always go slowly to to other project running that must be completed. However the first test seems to be good even if the signal level is quite low. I used the OPA1642 with a preampli and a second stage with a low pass filter. I hope to have better...

Hi Edwin Usually there are few specie of bats emitting vocalization with complex waveform different from the sinewave. If you see the first or the second harmonics it is due to artifacts when the sinewave becomes more and more closer to a square wave. If you take a look at the spectrogram of...

Hi Edwin, yes, I must add some other capacitor, I usually place 10uF and 100nF in parallel For very low noise circuit all the voltages must be very stable, so a voltage divider (is not supplied with a unity gain Op Amp) is not completely stable even if you place some capacitor. Moreover it uses...

I was thinking that in this way we need to bring the output around 1/2 vdd so perhaps a single supply with the mid reference is the easier solution with a phantom ground at 2.5V since the min supply range is ±2.25 V

Attached the preliminary schematic, probably there is still some error. I am going to produce some prototype so we are still in time for changes. Iv

Yes Edwin, the aim is to do it in the same board and eventually with the same shape so it can be available for everyone. However I can show how to solder the MEMS both with hot air and soldering iron, it's not so impossible to do at home Ivano

Hi, I'm trying to improve the analog amplification of the MEMS Many test done and not great results ... at least for the audio quality I need. My Ultramic384k is equipped with a differential amplifier because of the different application fields. The smaller series of ultramic has a single ended...

I'm using AD7988-5 but it is quite expensive, however on my Ultramic384K even if powered from USB there is a capacitive step up converter bringing the power to 5.5V and a low noise ldo to bring to 5V. I could propose other solution instead of this battery but we can talk later after solved the...

Right now I'm buying from Voir the VV-M126 membrane, it seems to be the best for ultrasound. I'll let you know as soon as arrived Iv

ok for the ADC, in the future we could think about this ADC: https://www.ti.com/product/ADS8685 about 5.5€ on Digikey for a single unit The paired MEMS could be placed front to front on the same PCB with an audio guide and amplification and filters close to them. I will try to do a schematic in...

For curious people, this is an open source project I am developing: www.narwhal-ai.org Ivano

hi there is no better sensor than another. My Momimic is not the "state of the art" of the ultrasonic analog microphone. I am always trying to find the best solution and even if in these years I did a lot of improvements i am still not completely satisfied. Unfortunately ultrasound behaviour is...

This test is well done but it lacks of high frequency test, and after 50kHz we can find the main differencies. For a good test it is important to have a reference with which to compare the results. I have got this equipment: SENSOR = B&K 4138 PREAMPLIFIER = B&K 2669 AMPLIFIER = NEXUS 2690...

Hi all I am new to this group and this project seems to me very interesting. I work with ultrasonic microphones since 1998, this is my website www.dodotronic.com Regarding the FG-23629: I use this sensor in the Ultramic384k. If compared to MEMS it is very insensitive to water and dust, moreover...

Hi, can you contact me? it seems to be impossible to send a private message dodotronic (at) gmail Thanks Ivano