This was how I implemented my WWVB nixie clock. Since I can't receive
60khz groundwave in Seattle during the daytime anyways, it makes sense
to have the display turn off in the middle of the night for sync.
With that said, not all switching supply controllers operate around the
same oscillating frequency. Although I've never done the measurements on
boost mode switching supplies, I have worked on this problem with
bucking supplies in music synthesizers. I found that although the
MC34063 seemed to increase and decrease frequency fairly sporadically,
the LM2575 stayed at a fairly fixed frequency. If you could design a
switching powersupply that was well grounded and only generated QRM on
frequencies other than the one you are listening on, then maybe...
You could also work on the antenna end of things. The standard loopstick
antenna is effectively a dipole. Since QRM is generally in the
electrical portion of the electromagnetic wave, you could build a
magnetic loop antenna and avoid hearing the QRM.
-Adam AJ9D
On 12/15/2011 9:03 AM, threeneurons wrote:
If all the above still generates too much noise ... cheat.
I have a store bought "atomic clock". Bought ~1996. Cost $170 back
then, and I considered it a bargain. It only uses the receiver once a
day, at midnight, to correct the time. So what you can do is, at say
3:00am, shut your switching supply off, and of course, the nixies will
also be off. Turn ON the receiver, and update your "internal time".
Then run off of the internal time, after your turn OFF the receiver,
and switch the supply back ON. If you're gonna have a uC in there
anyways, you might as well let it do something that resembles
"smarts".
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