Why do induction charged electric tothbushed make a noise?

[aussiblu]

The various Braun Oral Bs' we have make a very faint creaking
sort of whirring noise (while turned off) after being on their
induction charger. You have to hold them close to your ear to
hear it (well bay boomers like me who spent too much time in
night clubs listening to load music in the 70's do) but as
nothing should be moving inside why does it make this noise?
There is a simple coil in the base of the toothbrush that which
sit over the induction charger when it is seated in it. mainly
just curious although I also have a dead one that no longer
makes this noise and wondered if this was a clue to the cause (I
have opened the dead one up and their was just a little moisture
inside but no other obvious faults).

--
Regards
Blue

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[aussiblu]

Oops that should have been "toothbrushes" in the Subject Title

--
Regards
Blue

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[David L. Jones]

aussiblu wrote:

The various Braun Oral Bs' we have make a very faint creaking
sort of whirring noise (while turned off) after being on their
induction charger. You have to hold them close to your ear to
hear it (well bay boomers like me who spent too much time in
night clubs listening to load music in the 70's do) but as
nothing should be moving inside why does it make this noise?
There is a simple coil in the base of the toothbrush that which
sit over the induction charger when it is seated in it. mainly
just curious although I also have a dead one that no longer
makes this noise and wondered if this was a clue to the cause (I
have opened the dead one up and their was just a little moisture
inside but no other obvious faults).

--
Regards
Blue

Just tried it on mine, and yes it does make a noise. Mine is a series
of "clicks" at maybe a 5Hz rate, very consistent. Weird.
When I opened mine many years ago there was (from memory) just the
coil, a diode, and an 8 pin SO chip, plus the battery.

Dave

 

[DAC]

"aussiblu" <zxaussiblu@bigpond.net.au> wrote in message
newsPXeg.526$ap3.91@news-server.bigpond.net.au...

The various Braun Oral Bs' we have make a very faint creaking
sort of whirring noise (while turned off) after being on their
induction charger. You have to hold them close to your ear to
hear it (well bay boomers like me who spent too much time in
night clubs listening to load music in the 70's do) but as
nothing should be moving inside why does it make this noise?
There is a simple coil in the base of the toothbrush that which
sit over the induction charger when it is seated in it. mainly
just curious although I also have a dead one that no longer
makes this noise and wondered if this was a clue to the cause (I
have opened the dead one up and their was just a little moisture
inside but no other obvious faults).

I think you will find a capacitor and other components inside the coil
making a filter. It will discharge slowly through itself and as it does it
vibrates and makes a noise.