Basic dimmer switch for mains lighting

Just a quick question

On the older style dimmer switches (the modern ones all seem to have remote controls, and glowing bits, and all sorts of fancy rubish) - I'm talking about the ones that you simply turn to make the light brighter or dimmer - are these just a large potentiometer? or is it a small rehostat or something?

Thinking about it - what is the difference between a potentiometer and a rehostat? (if thats how you spell it)

Thanks

Tim

this is what they basically contain:

http://www.geocities.com/tjacodesign/dimmer/dimmer.html

using a simple potentiometer would mean a great loss of power.....

Here is a very simple dimmer.
Rheostat is a variable output toroidal trafo.

ok, thanks guys

Sebi said:

Rheostat is a variable output toroidal trafo.

Click to expand...

err, what?

grrr_arrghh said:

ok, thanks guys

Sebi said:

Rheostat is a variable output toroidal trafo.

Click to expand...

err, what?

Click to expand...

I think he means a transformer (trafo), but I would disagree, a rheostat is a large (very large!) wirewound potentiometer. Whereas a transformer would only work on AC, a rheostat works on DC as well.

The ones they had back stage at my old school were scary, they were actually sliders - and pretty well open, to dissipate the heat. Imagine health and safety nowadays :lol:

ok fair enough, thanks

lol, health and saftey would have a fit!!