[time-nuts] ES100 WWVB clock notes

[Tim Shoppa]

After some initial evaluation in December last year, I've done some more
work and prototyping with the ES100 WWVB chip+board from Universal Solder
in various clock applications. Most of my work uses an Arduino Nano for
processing.

What I like is that the ES100 puts out data in UTC, which is a little
ironic because historically most consumer WWVB clock chips only display in
North American time zones and cannot be set to UTC.

Some of my playing around includes working on a bench with switching power
supplies and/or using multiplexed LED display modules.

It's no surprise - the ES100 vendor's notes make it perfectly clear that
these are sources of interference - that having a switching power near the
WWVB antennas, or having a multiplexed LED display within a foot of the
WWVB antennas.

I'm not sure any of you made "calculator music" with 8-digit LED
calculators placed next to an AM radio in the 1970's, but the multiplexed
LED displays are raucous sources of near-field noise. I can confirm that
the popular 8-digit 7-segment displays modules driven by MAX7219 chips
produce this same kind of noise.

A piece of good news, is that as long as I keep the ES100 ferrite loop
antennas a foot or more away from these noise sources, they seem to work
fine.

I am actually observing very good daylight sensitivity here in Maryland, to
the WWVB signal from Colorado.

My big clock project this summer is a ES100 clock using 4" high 7-segment
LED displays (driven by TPIC6C595 so not multiplexed), housed in a wooden
painted case inspired by the GOES Bicentennial Clock pictured here:
https://www.researchgate.net/figure/A-satellite-clock-built-for-the-U-S-Bicentennial-in-1976_fig6_241637745

Tim N3QE