[ale] More on LEDs...

[Mike Harrison]

> but bad at distributing it. He said that rather than the supposed 60hz that they're supposed to
> deliver, it's usually a little less than that - say around 58-59Hz. It's usually close enough to not
> fry everything from brownouts, but also low enough to lower the longevity of things like these

Frequency is something that is usually, unless there is something very 
wrong at generation, not distribution. 59.99hz to 60.01 kind of 
normal range. It does vary, but should not by much.

http://certs.lbl.gov/pdf/nerc-fma.pdf

The Phasor measurement project mentioned here is a very big and successful 
Hadoop based project.  Lots of Linux and other things being used.
A lot of that was developed her in Chattanooga at TVA, and is now
a big project at TVPPA.org and other places.

Page 16 shows some data for average frequency variation. .01 is a lot.

What will vary is voltage, and sometimes how "noisy" that sine wave is.
ie: bad harmonics because a neighbors bad HVAC unit is dragging and the 
available current at the voltage is off a little or a lot (LOT) of 
switching power supplies in your house putting "shoulders" on the sine 
wave..