Add circuit theory documentation

[shanemmattner]

It would be great to have a brief description of the circuits and perhaps some links to documentation explaining how the circuits work. I can help create the documents if you'd like

For example, in the picture below of U2A/U2B:

• U2A is a voltage buffer
• R5/R8 divide the input by 2
• U2B is a summing differential amplifier
  • Is this correct? Perhaps the equation for this circuit would be helpful

Then U3A circuits:

• U3A is a fully-differential amplifier
• Output of U3A fed through RC filters (ie R6/C4, R11/C7) with cut-off freq ~59Mhz
  • Why 59Mhz?

[AlperenAkkuncu]

It would be great to have a brief description of the circuits and perhaps some links to documentation explaining how the circuits work. I can help create the documents if you'd like

That's a good idea. I was thinking about making videos, but I am not too sure how difficult it would be. Documenting stuff on github is a lot more efficient for me actually.

• U2A is a voltage buffer
• R5/R8 divide the input by 2

That's correct

• U2B is a summing differential amplifier

That's not correct, it's just a non-inverting opamp, if you follow the nets analog mux (U5) connects the resistor networks to achieve different gains.

Output of U3A fed through RC filters (ie R6/C4, R11/C7) with cut-off freq ~59Mhz

• Why 59Mhz?

It's kind of random, usually you need to use the lowest BW that you can work with to drive the ADC. Driving ADCs are quite difficult because it needs a lot of bandwidth. Determining exact values are quite difficult it's just requires quite a lot of trial and errors.

[shanemmattner]

Making videos can be as involved as you'd like to make them. I just uploaded some new videos on using SKiDL to make an ESP32 data logger (analog front end based on your project, thank you!). You'll see they are pretty basic and just me talking over a screen.

[AlperenAkkuncu]

Making videos can be as involved as you'd like to make them. I just uploaded some new videos on using SKiDL to make an ESP32 data logger (analog front end based on your project, thank you!). You'll see they are pretty basic and just me talking over a screen.

Once I get an OK mic I can make it. Great stuff by the way. :)