Question on transformers (toroidal not robots in disguise)

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attractivebrunette

I've put up 12v track lighting with a 300 VA toroidal transformer. Works fine.

Now I've changed the switch for a dimmer and the transformer buzzes very loudly.

I spoke to the company that sold the transformer and they say I need a particular type of dimmer switch that works with 12v lighting.

But some people on Internet forums say I need a special dimmable transformer.

Who is correct?
 
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You need a dimmable transformer, the switch won't make a difference.
 
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attractivebrunette

Arse. Is there such a thing as a dimmable toroidal transformer or does it have to be an 'electric' one?
 
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you need what is known as an Inductive dimmer.
Assuming that is you have a Torroidal wire wound dimmer you need a 300va or more rated dimmer.
 
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I would have thought a toroidal transformer would be a bit of old kit and yes I know they work well but the inrush must be something quite large and to get a dimmer to work with these would be quite a challenge and likely far bigger than will fit into a light switch back box.

Likely you would need a variable transformer or like to feed it.

It does seem strange why one would want to dim 300 watt of 12 volt lighting as in the main 12 volt lighting is of the quartz type which work by keeping the quartz envelope so hot the tungsten can't be deposited on it. So to run cool would really reduce the life of the lamp.

Manufactures have gone to great lengths to keep the voltage to within very tight limits using today switch mode power supplies to remove any mains voltage variations and feed the lamps with the spot on voltage required. Although some can be dimmed it rather defeats the whole point of using quartz lamps.
 
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I've put up 12v track lighting

I would have thought a toroidal transformer would be a bit of old kit

Most, even new wire track systems use them eric, due i think to the lengths of the wires which can be a few metres and the fact that the two output conductors are some distance apart on the span across the room.

Electronic ones nearly always stipulate the lead lenghts and rarely more than one metre, im sure theres a technical reason and i think also its to conform with CE regs due to harmonics/ interferance
 

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