In the "Nano Hex and Menu.PDF"

Select "Various NANO board Modifications" from the Index.

It's the 2nd image titled "Board 2 with a CH340 USB controller"

Nothing in the Inverter SPWM code or timing has changed, and of course it's silent in both the Test inverter and the Beast.

But as you mentioned, there are so, so, so, so many variables in these DIY builds, I could list a dozen right off, any one of which could influence the Toroid AC generation noise levels.

I went through that phase after a high current incident, there was a buzz in the Toroid at idle all the time.

I used the Same Toroid in another build, and it was silent    

  Quote  

The battery and capacitor values have been within .1volt all the time and remain strong under load.

It was not your settings, I have the margin set quite high when checking the running status.

Edited 2025-04-30 08:46 by KeepIS

  Quote  

don't know which cap it is on this nano.......(see photo)

Re the reset capacitor, probing a Nano the reset pin is connected to the small one bottom right in your pic.
Close to the header pins and also connected to the 1kΩ (102). The other end of the cap. goes to pin 12 of the CH340G.

  Quote  

Select "Various NANO board Modifications" from the Index.

It's the 2nd image titled "Board 2 with a CH340 USB controller"

Yeah, I see it on the picture of board 2 the little cap is in the same place but the track looked to go under the CH340 on the one I have, and the 662K 3.3v sot23 voltage regulator (top left) made me look at the last nano in the list.
So if its the same its easy to knock off that little cap.

Ok thanks Phil, I should get the probes and check.
Edited 2025-04-30 09:30 by Revlac