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The voltage offset puts the center of the signal at the middle of the esp32 ADC, roughly 1.6v. This is very common and necessary when taking an audio signal that centers ant 0 into a computer that is only + voltages. The clipper just protects the ADC from over voltage.

I’ve studied this guys videos, specifically on grounding. Great stuff, very informative:

Hmmm. I suspect any EE will strongly disagree with this method. But I’m not knowledgeable enough to explain why. I’d suggest posing this question over on AAC. (Then report back to us!)

Regarding grounds. I’m no expert. But I’ve been told that a 4 layer board with an inner ground layer and the other 3 with ground planes is FAR superior to a 2 layer board with ground planes. I’ve recently learned how to do this in EasyEDA, it’s practically the same price as a 2 layer at JLC.

Please elaborate

Here was my latest cost for 5 assembled prototypes, just to give an idea on cost. $30 extended fee means I had 10 extended components $3 each. But everything else is so cheap, all the resistors and most of the caps/diodes are basic, literally pennys. They also allow an initial 5 boards but only...

No the 3 electrolytics are extended but still economic not standard. The only thing that tripped me over to standard was assembly on both sides. Initially I wanted the 12-pin JST on the bottom, but it increased the cost a lot. So I found a way to put it on top and keep it economic top side...

I did some digging on trace width. For signals, the default of 0.254mm (0.1") is completely adequate. Even for power that's probably fine. I did some calcs with 150 mA of current on an internal layer (hotter), and it only requires a trace width of 0.05 mm. 150 mA is a lot of current for most...

Op amp wise, the only Basic I found was the TL072. I can't find a basic one for MCP6002, and more strangely, I can't find a basic NE555 timer?!? Oh well. But yes you're right, SOIC-8 is generally best. I'm using the standard footprints that come in EasyEDA. The only footprint I created was for...

Great thread. The EOL date for Eagle has been looming, and I have wanted to learn SMDA so I took the plunge into EasyEDA. 2 weeks in, I've got most of it figured out. For Q-tune, I've been able to take the thru-hole design in Eagle, and (starting from scratch), re-create an SMDA version in...

Yes. @chongmagic had the same issue, PS was only putting out <8v. The relays will not function properly without at least 9v.

Great news. Yeah the voltage drops from PS through 555, 47R, to relay all add up. I tested it at 9.0 and it worked, but most 9v supplies push 9.2-9.4v so it’s rarely an issue. Post #551 of this thread details the math if you’re interested.

Have you flashed the new screen and tried it? I'm still wondering about those 12 pins in the JST connector of the screen. Make sure they aren't bent on the old screen. Just to be clear, can you confirm I'm understanding right what is and what isn't working? And also try the monitor mode and see...

Honestly the Peterson Mini is an amazing tuner, and for it's price, not only the best commercially available tuner but also the best value. It's what I'd use if I didn't have a Q-Tune. I was a loyal Turbo Tuner user for ~15 years, but the Peterson Mini is better. The No Screen / No Enclosure...

Check to make sure no pins are bent in the 12 pin JST on the screen. The outermost pin is the one that is most easily bent, it goes to GPIO15 and controls the TB-BB relay.

Does it tune in both TB and BB? But it only plays (passes signal) when in BB? So you can use it in BB? I'm staring at the signal path trying to understand where the signal goes and where it doesn't go (but should).

Is that a question or a statement? Assuming it's a statement, that is odd. If in TB, the ONLY thing in the path are pins 8,9 of the relay (IC6) and the bypass relay IC5. If you hear both relays clicking, it should work.

I made it to 50 without needing readers. Now at 52, I can't cut my fingernails without them. I can't even look at a circuit board without my headband magnifier. Gettin' old sucks.

Quick readings on mine. One spot PS: 9.45v V+ side of R12: 9.08v Regulator side of R12, Vin: 8.25v Vin (same as above): 8.25v Vout: 5.0v I probed ground on the JST.

Right. Measure pins 1 and 3 of IC2. For ground, I'd probably NOT use pin2 (too easy to short out the regulator), but instead use a ground somewhere else on the board. There's 2 on the JST connector, or audio jack grounds are easy to grab. It sounds like the regulator could be bad.