12V Downlights and Dimmer Issue

[bosyuk]

We have 6 12v 50w down lights in our kitchen.

The switch is a dimmer switch, previously we used to be able to dim very low.

Now as you turn the dimmer down they just turn off at say 20w for example. At other times we have been in there in morning and had them quite dim and they just turn off until you up the dimmer a bit.

Its not the biggest problem but if something is on the way out don't want them to stop working.

I've looked at one of the lights and the transformer its running is a:

Teclite Model TL60ET (20VA-60VA)

Could this be the dimmer switch or am I being too optimistic?

 

[sparkybird]

what's the rating of the dimmer switch?

 

[ericmark]

The Teclite Model TL60ET (20VA-60VA) is not just a transformer, the clue is in the minimum power of 20VA it is an inverter designed to keep the voltage to very close tolerances even if the supply voltage varies. The whole idea of the quartz lamp is to keep the temperature of the quartz at the temperature where tungsten from the element is reflected so it is re-deposited onto the element so increasing the life. It is completely pointless to reduce the power after paying so much to keep the power steady. One may as well just use GU10 fittings which are easier to install and can also in future be used with discharge lighting instead of the tungsten.

Yes you can dim some inverter outputs but to work well you need to use same make of inverter, dimmer and lamp. But the dimmer works by chopping the wave form and it also tends to put some harmonics on the supply and output at same time. It can chop the lead or lag and so needs matching with the inverter.

Even the bulb has a coil or sometimes a coiled coil so there is some inductance and capacitance and they are not pure resistive loads. I have seen many times where a dimmer has either not dimmed as required or made a noise and simply changing the lamp has cured the problem.

And any quartz lamp even at 20W is quite bright so since 20W is minimum would it not be much easier to just put lamps in a 4 and 2 bank so you can use 2, 4, or 6 lamps?

 

[ban-all-sheds]

We have 6 12v 50w down lights in our kitchen.

The switch is a dimmer switch, previously we used to be able to dim very low.

Have you recently replaced the light in the kitchen with these 6 downlighters?

 

[bosyuk]

Thanks all. These lights have been in for a couple of years. They were here before we moved in.

We haven't made any changes at all. My girlfriend just said she was in there one day with the lights dimmed and they made a nice like a computer system shutdown sort of noise and went off.

She just turned the dimmer up a bit and they came back on. They have been like this ever since.