Well, thinking here is a bimetallic strip feeding a heating element would be
broadband,as there is nothing periodic in that like a 35 kHz swticher for
instance,
Oh - I have tracked down a couple doorbell transformers, one that was activated
by the
switch continuously and must have overheated and buzzing as the overload
thermostatcycled, and another that failed in the Texas spring to summer
transition and that onetoo was cycling and creating a cyclic buzz.
So, more to chew on.
de AA5CT Jim
On Monday, May 27, 2024, 11:13:52 AM GMT-5, K9MA <k9ma@sdellington.us>
wrote:
On 5/26/2024 11:23 PM, AA5CT wrote:
Another possibility - aquarium heater? One of those jobbies that clamps over
the edge of the
aquarium in a glass tube maybe an inch diameter and 4 or so inches long.
I did once track down one of those, but it had the characteristic spectrum of a
switching supply. This one emits absolutely flat broadband noise, more like a
spark gap. It is on for about 1 second every 4 seconds. I'll do some more
tracking today.
73,
Scott K9MA
--
Scott K9MA
k9ma@sdellington.us
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