[time-nuts] Building a mains frequency monitor

[Bill Hawkins]

The schematic is too simple. There is noise on the power line from
switching things on and off, leakage from dimmers and switching power
supplies, and the occasional animal that gets across the HV distribution
line, not to mention lightning, induced or direct.

A simple capacitor will reduce high frequency stuff. The purist will
invest in an L and C that resonates at 60 Hz. Alternatively, use a
synchronous motor driving a load with sufficient inertia in combination
with a slotted disk and photo pickup. Perhaps an old record turntable
will do - but not one with a regulated DC motor.

The science fair folks got enough interesting data without all that, but
the precision is not known.

The link didn't have any reference to code at all.

This is a way of looking at frequency variations with natural causes
that does not require expensive equipment, if done right.

Bill Hawkins


-----Original Message-----
From: Nick Sayer
Sent: Friday, April 08, 2016 7:20 PM

The instructable I wrote about it is at
http://www.instructables.com/id/Science-fair-How-accurate-is-the-AC-line
-frequency/

There's code for the Arduino and the Linux side as well as schematics.