Exhaust fan for soldering build

[lilfear1]

Hey everyone...I build this exhaust fan out of an old pc fan 120mm with a switch and attached to a power supply that was I think an old cell phone charger...the old type not the usb type. I kept all parts of the power supply except for the very end which I cut off and soldered it into the switch with the fan.

Power Supply Specs:
input: 100-120V ~ 50/60 Hz 0.3A
output: +12V dc 1A
Fan specs:
120mm
dc12V 0.37A
and switch i pulled out of a broken motorcycle battery charger.

My problem:
The fan seems to work GREAT, fan works GREAT. I have even had it run for about an hour and I smell nothing or see nothing that is bad.
BUT while it is plugged into the mains i hear a super tiny buzzing sound or humm or something. I think it is coming from the power supply but I can't really tell.

I do have tinnitus so I am always hearing buzzing, but I was a mechanic for 15 years and I can still hear things that are abnormal, and this is abnormal.

 

[HellasTechn]

The noise is either from the switching power supply you use of from the fan itself.

If from the PSU then you will probably have to get an other one because i dont think there is a way to fix that.
If from the fan then try a little lubricant on it's saft and if that doesn't help then...

 

[lilfear1]

I only hear the sound with the fan turned off but plugged in

 

[lilfear1]

why would there be that sound? what would cause that

 

[duke37]

Magnetic materials can change shape when magnetised (magnetostriction) so transformers will hum. If the core consists of metal laminations, they can tap together and be quite loud. Should not affect the operation.

 

[lilfear1]

Magnetic materials can change shape when magnetised (magnetostriction) so transformers will hum. If the core consists of metal laminations, they can tap together and be quite loud. Should not affect the operation.

The sound kind of pulsates...but thank you

 

[eKretz]

Most likely the switching power supply. Many make more noise when they aren't supplying power and are in a sort of "hiccup" mode. It can be annoying but is completely normal. The switching frequency is usually lower on cheap wall wart style switchers, so it's still in the audible range.

 

[lilfear1]

Fantastic thank you