DIY Perks Mic Troubleshooting
I have wasted way too many hours on this projects and at this point I really need a second pair of eyes, because the issue is related to either something I don't know, or something I'm missing.
My take was designing a one sided pcb and etching a copper plate and it was a success. After placing all the components exactly as in the video I dont get any output signal, and I'm starting to doubt everything. Is the Mic capsule + transistor working? Is it the preamp ? Is it the Analog to digital ?
I'm attaching the preamp circuit to make sure I have recreated the tutorial's circuit correctly.
***important update 3:
Important information to add, that I just noticed.
The voltage between pins 5 and 6 is 0.635V - 0.637V depending and changes when i rotate the gain switch. The Voltage of "around 1V" is actually negative and starts at about -1.1V ands as times passes it drops, thats why I was measuring -0.8 and even reached -0.4 if I did multiple tests in a short time. Pin 5 is Ref and is directly connected to t he red output cable (thats why i didnt notice it was negative output voltage) and Pin 6 is the output signal that goes through C5 (bipolar 22uF) and then to the black point.
***end of update 3
My take on recreating the exact same circuit as in the video
This is my first time using KiCad and etching a pcb and it took several weeks to successfully "print" the circuit in hopes of not having to troubleshoot connections as it had to be perfect by design.
I noticed the NMA0515SC is getting pretty hot but there are no bridges and I'm actually proud of how good the copper clad etching turned out.
At this point I want help from you guys to verify that this circuit is the exact same as the one in the video and if so I'd like you to share your ideas about where the issue might be.
The output of the preamp is at about 1V, I didnt use the exact same analog to digital audio interface in the video, but a cheap sound card that actually works pretty well with another mic I have so that shouldn't be the issue. I bought all the resistors and capacitors from a local electronics store but they told me that 22uF for a Bipolar capacitor is huge so I hope the one I ordered from ebay is good quality.
The microphone is bought from the official reseller in UK linked in his video description and the transistor, the NMA0515SC and the THAT1522 THAT1512 are bought from AliExpress, so I'm hoping its not a matter of components quality but a stupid mistake that I cant see in my design.
Thank you all in advance and I'm looking forward to you bringing some light to this project.
Update1: Attaching photos of my board, after moving the R1 and R3 to +-15V as previous comments stated.
No bridges, I checked thoroughly
Front after fixing the R1 and R3
Measured Yellow at -11.14V and red at +11.14V
Update 2:
Adding Mic connection photo from guide
Top right yellow, bottom right red bottom left goes to mic center top left unused
