I have a 'smart-socket' based B-7971 clock and have the boards set to
'fade' between digits - the noise is super audible - I guess I could/should
change it to instant change to reduce the noise but it's only PIR triggered
to is mostly off!
For bedside clock I have an IN12/IN17 clock from PV
About 3 years ago I gave away my extra boards (only charged for shipping)
to 3 members of this forum; I just sent out a ping to see if anyone has
built theirs yet. The gerbers and docs are posted to the private group (
https://groups.google.com/forum/?hl=en#!forum/b7971-driver-board-user-group
That is the problem with my MM5311 based B7971 clock that I built 40
(ugh) years ago. The multiplexing causes the tubes to whine. It did not
bother me much when I was younger but as I got older and was not sleeping
as soundly, the noise became bothersome. I tried changing the frequency but
its
