low voltage light fitting on dimmer switch is buzzing.

[paxman21]

I have just fitted a low voltage light fitting with transformer already built in, This runs from a dimmer switch.

When turned on at any amount of dimming, the light fitting makes a buzzing sound which becomes louder the more the lights are dimmed.

The dimmer is 400W, the lights are G4 bulbs, 5 x 20W - 12V

Anybody know how to stop the buzzing?

 

[ban-all-sheds]

Yup - fit a dimmer that is OK with ELV lighting "transformers".

Use a "transformer" of a type that can be dimmed.

Make sure even so that the way the dimmer works (leading edge or trailing edge) matches what the "transformer" needs.

 

[paxman21]

Thanks for your assistance- I don't quite understand leading edge etc- your last comment? But I'll try a ELV dimmer switch first!

 

[breezer]

some of what ban-all-sheds is saying you can not do.

He suggests you get a compatable transfromer and dimmer switch, but as you said

with transformer already built in

you can not.

It may be that the light fitting you have is not suitable for dimming, you will have to see what its transformer says.

alternatively try a differnt brand of dimmer switch

there are several types of dimmer swicth trailing edge and leading edge. it is also possible you have the wrong type.

Personally i would look at the transformer first to see what it says

 

[paxman21]

Thanks for your reply-

I checked the label on the transformer and it doesn't mention anything about dimming- The instructions don't either, so I guess it's probably ok?

How do I tell what dimmer to get?

Cheers

James

 

[breezer]

if it doesnt mention dimming then i would say it is probably NOT ok.

electronic dimable transfromers state they can be dimmed.

Yours may not be an electronic transformer though. What exactly does it say?

 

[ban-all-sheds]

Thanks for your assistance- I don't quite understand leading edge etc- your last comment? But I'll try a ELV dimmer switch first!

The difference is how they work - whether they remove the leading, or trailing edge of the input waveform. Each type is best for particular types of loads, which is why if you use the wrong sort on electronic transformers you get horrible buzzing noises etc.

Try http://uk.altavista.com/web/results?tlb=1&fr=tb&kgs=0&ienc=utf8&q=+leading++trailing++edge++dimmer*

 

[paxman21]

Thanks again for your assistance guys...

The transformer is within the base of the fitting... it states 105w on the underside of the fitting, and a load of other badges and TUV approved etc.

The dimmer switch is 400w rated, I don't know if this helps but dimming isn't mentioned anywhere?

I've just checked the back of the dimmer and it says it's 1 or 2 way, 400w max and 60w min, 216v- 253v 50 Hz? I dunno if this helps

Sorry moderators!!
_____________________________
Moderator

paxman21 please note 10a

 

[ban-all-sheds]

dimming isn't mentioned anywhere?

Breezer's right - this probably means that it can't be dimmed.

 

[paxman21]

Guys thanks so much for your help, top blokes, top forum-

In the end I just switched a normal switch onto it and the buzzing has completely disappeared!! Fantastic

Regards James