Best way to convert peak voltage to RMS?

[Darrel Taylor]

The RMS value is only .707 of peak if the waveform is a perfect sine.
With a guitar input, that is not the case.

Converting to RMS using just an analog input and software takes many many samples per cycle and lots of math.
It's much easier to use an external RMS to DC convertor like the LTC1966.

The LTC1966 comes in a TSSOP package, so it's really small.

[HankMcSpank]

Hi Darrel,

this is for an AGC for a guitar sustainer circuit (a sustained/infinite guitar note is pretty much a perfect sine - because it's only the initial pluck that's full of harmonics & they drop out quickly), but I take your point about about the cycles & maths involved...