On 13/04/2018 15:44, The Natural Philosopher wrote:
On 13/04/18 15:02, newshound wrote:


My point is, do the low pass filtering in software, though.

A bridge rectifier and smoothing cap is a peak voltage reading abortion
for this: you want to do an RMS average especially for kettle elements.

My solution is less components, but more code.

Code is cheap!

Only issue is doing a square root in binary integers...arduinos don't
have native floating point ****!


Let's park that for the moment




As you say, small mains transformer, a few resistors and of course a 5
volt Zener on the ADC input.

Well i'd just clamp that to the 5V rails.

Clamp what? I'm confused.

You will run at a high impedance so no damage dumping the odd mA into
the supply