Curious Question buzzing and dimmers...

Electricalserv · Apr 23, 2011

Back when I was in training I always remember the boss had a problem with a buzzing dimmer on downlighters.

Solved it by changing the voltage of the dimmer....

Can someone tell me why the dimmer buzzed, didn't take enough interest at the time but would like to know why???

telectrix · Apr 23, 2011

like to know the answer myself. bloody pain with dimmers buzzing.

Electricalserv · Apr 23, 2011

It must be something to do with the voltage rating as he changed it and the buzzing stopped.

RWJ · Apr 23, 2011

...... Where's IQ when you need him.......

Right

They buzz because they "chop" the ac wave before it gets to the peak to lower the output voltage.
It's switching 100s of times a second
Compare it to a strobe light but faster... That's where the buzzing comes in.

Sorry for the quick reply, but it's not easy one to answer with two kids calling you!!!!!

EDIT..... Sorry the first version didn't quite make sense. It was like talking to the man in the Chinese

malcolmsanford · Apr 23, 2011

It is dependent on if it is a Triac or a Thyristor type. Though a Triac is just a combined number of thyristors in a single situation normally 2.

Whichever ones you choose they are basically just high speed switches and they are chopping or interupting the sinosidual mains wave on it's cylce, in other words they are taking our nice curve wave form and making it square.

A transformer that is designed for use with a Triac dimmer will be ok. A transformer that isn't puts the Triac under stress and that is the low buzzing sound you can hear as it's literally working against itself, and the more lights or load on it the louder it will be.

The reason I know this ...................lol I just had to fit some dimmers into a conference room as the ones installed less than 6 months ago were buzzing.