How do you dim a CCFL? Want to brighten and dim a set of CCFL lights as needed.....

[herbiehancock]

I want to know if anyone has managed to put a dimmer-type thing on a CCFL light? I want to have the ability to brighten and dim some according to what I want to do....have two colors and make one color a bit brighter than the other when I want to. Could a variable rheobus, rated at 1.67A and 20W per channel, do that without burning up?

 

[Rubycon]

Do NOT reduce the voltage to the inverter. It will likely shorten the life of the tube(s), inverter or both.

Unfortunately, the only (real) way to provide a variable output of this type of light source is to use an inverter which employs pulse width modulation (PWM). The circuit is straightforward and of rather intermediate skill level for the hobbyist with experience.

There may be inverters that have this capability built in that's invoked by changing the input voltage.

 

[herbiehancock]

Would it make any difference if the rheobus was a PWM rheobus?

 

[Rubycon]

No it would not make any difference.

 

[zephyrprime]

Don't even think about a simple DC trick like a rheobus.

There may be inverters that have this capability built in that's invoked by changing the input voltage.

I believe there are such things for cfls. They would be marketed as simply being dimmable. Besides this, there are special inverters with the ability but I don't know how exactly the setting is controlled.

 

[Bob Anderson]

Dimmable compact fluorescents have just come on the market in Canada. Google Philips and the other major manufacturers.

I don't need dimmables myself. I converted every incandescent in the house to cf's a few years ago. I use Philips Daylight which are whiter than white, about 9200K. No more dingy yellow incandescents for me!

-Bob

 

[MagnusTheBrewer]

Originally posted by: Bob Anderson
Dimmable compact fluorescents have just come on the market in Canada. Google Philips and the other major manufacturers.

I don't need dimmables myself. I converted every incandescent in the house to cf's a few years ago. I use Philips Daylight which are whiter than white, about 9200K. No more dingy yellow incandescents for me!

-Bob

Some of us LIKE dingy yellow incandescents. 5200K ftw!

 

[SuperNaruto]

I just bought a place and replace all the 100w bulbs to the 5500k.. some of the bulb are 6500k.. I never seen 9200k before.. isn't that like purpleish ?

 

[severtki]

That's my problem with this whole push (even mandate) to CFL -- most of the rooms in our house have dimmers on them, and I'm rather loathe to switch all those switches out and lose dimmability... and get ugly blue light to boot.

 

[Bob Anderson]

Originally posted by: SuperNaruto
I just bought a place and replace all the 100w bulbs to the 5500k.. some of the bulb are 6500k.. I never seen 9200k before.. isn't that like purpleish ?

Sorry, I made a mistake. The Philips Daylight CF's are 6500K, not 9200K. The light is pure white, there is no color component to it. 9200K would have a bluish tint.

-Bob

 

[bob4432]

why is there a warning on the cf lights to not use them with a timer? that is what annoys me. we have a couple ligths that i still use regular old incandescents because everybody says don't the cf on a timer...

 

[Bob Anderson]

Originally posted by: bob4432
why is there a warning on the cf lights to not use them with a timer? that is what annoys me. we have a couple ligths that i still use regular old incandescents because everybody says don't the cf on a timer...

There is no warning on my cf bulbs concerning the use of a timer. They can't be used with a DIMMER, unless the bulb specifically says it can. I think whoever told you a cf can't be used with a timer can't read.

-Bob

 

[bob4432]

Originally posted by: Bob Anderson

Originally posted by: bob4432
why is there a warning on the cf lights to not use them with a timer? that is what annoys me. we have a couple ligths that i still use regular old incandescents because everybody says don't the cf on a timer...

There is no warning on my cf bulbs concerning the use of a timer. They can't be used with a DIMMER, unless the bulb specifically says it can. I think whoever told you a cf can't be used with a timer can't read.

-Bob

i can read and have read it myself it is not on all the bulbs, but i will see if i can take a pic of one that says it....

 

[xtknight]

Just to reaffirm...backlights in LCDs tend to modulate at 200-400 Hz to vary the brightness. (Though most is done via the matrix and the cells themselves.)

 

[Rubycon]

If the timer is electromechanical (electrically this would be IDENTICAL to a SPST switch - aka light switch on the wall) you can put any kind of load you want on it up to the rating. If the timer is solid state and specifically uses the word TUNG for load, it will damage (or at least make them act strange) loads other than tungsten bulbs. Some solid state timers may get caught in a loop of hysteresis and bounce rapidly on and off when a load (such as a cheap CFL) producing a lot of harmonics is connected.

If you have a dial timer with trippers, it should be safe for anything. If it's digital, RTFM.

 

[Jiggz]

Most timers will clearly state if you can use CFL's as load to its circuit or not. To be sure, always read the label. As for CFL's having this warning is kinda ridiculous since it'll never be affected except that it could be blinking rapidly because a solid state timer gets affected by the circulating current or by the harmonics of the CFL. Anyways, there are now dimmable CFL's and it's clearly advertised on the bulb packing. If it doesn't say dimmable, then it cannot be connected to a dimmer light. This doesn't mean it will not work, it's just that the CFL will not last, not even 2% of its expected MTBF hours.

 

[corkyg]

This is a pretty good list of CFL FAQs:

CFL

Go Canadian Football League! (CFL)

BTW - OP asked about CCFL - those are different than CFL.

CCFL

 

[wgoldfarb]

Originally posted by: Rubycon
If the timer is solid state and specifically uses the word TUNG for load, it will damage (or at least make them act strange) loads other than tungsten bulbs. Some solid state timers may get caught in a loop of hysteresis and bounce rapidly on and off when a load (such as a cheap CFL) producing a lot of harmonics is connected.

If you have a dial timer with trippers, it should be safe for anything. If it's digital, RTFM.

A bit off topic, but does anyone know of a good online source (in the US) for solid state timers/switches compatible with CFLs? My local hardware store only has one solid state model and it is not CFL compatible.

EDIT: I already tried Google, but the results I got were for industrial switches, I could not find any sellers offering household products.

 

[Rubycon]

Intermatic should still be making electromechanical ones.

That failing, you can use an electronic timer to energize the coil of a relay to turn your CFL's on and off.

 

[wgoldfarb]

thanks!