What could be making this noise ???

[MathWizard]

I'm in my house and I keep hearing through the wall, from another apartment, what sounds like 60Hz hum.

At 1st I was imagining it's the Fog horn that's miles away, getting amplified by my concrete basement, but I was half asleep.

But I unplugged everything by an adjoining wall, thinking it was some transformer. But I still hear it. It turns on for about 6-8 seconds, IDK for sure if it's always the same, but about that. Then it's all quiet for about say 1min 10sec. IDK if the off time is always the same either, but it's pretty close to it. I've only been noticing this for a couple of days.

If I wasn't in the middle of doing some AVR coding, I might try hooking up a little mic circuit, and looking at it on a scope.


But could it be a fridge or deep freeze ?? Would any of them only be on for a few seconds, then off from a little over a minute, for 2 days or more ??

[thm_w]

Either record with PC then FFT, or get out your phone and run an FFT app. This will tell you the exact frequency and let you time the on/off durations.

Seems far too short of a on/off time for a fridge, usually those are in the 10-30min+ cycle time I would think.

[Bud]

Could be a failed furnice cycling trying to start.
Or a failed garage door opener.

[edpalmer42]

Yes, it could be a fridge or deep freeze.

If the compressor seizes up, it tries to start and draws maybe 20 - 25 amps compared to a normal running current of 1 - 2 amps.  After a few seconds of this, the thermal cutout kicks in and disconnects the power.  After it cools down enough, everything restarts.

This is normal if you just had a power failure, but it clears itself after less than an hour with no damage.  If it's been going like that for a couple of days, the compressor, the deep freeze, and the food, is garbage.

[MathWizard]

On Sunday it seemed to come on a bit more often, but whatever it was, it's gone away since sometime yesterday. I'll have to listen and see if now it runs for a few minutes and shuts off for ages like my fridge.