Cathodes on a Rheostat?

[Foxie3a]

Would it be safe for the cathode if it was on a rheostat?

I am thinking of putting two of them on one, so that I can change the brightness of them, will this work? will it blow the cathode out?

[Dc5e]

well i really don't know much about cathodes... but what kind of power consumption do they use? 12v? You most likely won't blow the cathode out, but its possible you can burn out the Rheostat if its not rated high enough. and also, can they even change brightness?

If you can find out the power consumption(amps or miliamps) each cathode uses and the voltage, you can calculate what kind of rating the rheostat requires

[Foxie3a]

well, dont rheostats usually have 20watts per channel..

I doubt that a cathode will be more than that.

and I figure that if I put less into them, they will not be as bright.

[sandman001]

@0watts for a channel is VERY good for a rheo. The sunbeam has that, but most others have anywhere from 8-13.

[L337 M33P]

Cold cathodes have something like 100V inverters that run off your supply. They are designed to work with a set voltage and put out a set voltage, so decreasing the input voltage will most likely stop them working.

[Foxie3a]

how about the PC TOYS ones..cause those are very cheap.. :-D

[L337 M33P]

No. All CCFLs come with inverters.

[Foxie3a]

can I throw them onto a switch so they go on and off? :)

[L337 M33P]

Yes - you just can't control their brightness unless the inverter is adjustable, that's all. Switches will probably work fine.

[Foxie3a]

can I buy a seperate inverter and hook it on there?

[L337 M33P]

? Why would you need another inverter

[Foxie3a]

an adjustable one

[donny_paycheck]

Originally posted by L337 M33P
Cold cathodes have something like 100V inverters that run off your supply. They are designed to work with a set voltage and put out a set voltage, so decreasing the input voltage will most likely stop them working.
Yeah, it will decrease the voltage to the tube to a point below its ionization threshold and the gas will go dark immediately. The only way to controll brightness that I am aware of is to make sure you don't go below that point. They don't work like LEDs or incandescent bulbs, which will go down to nothing linearly.

Also I moved this to Alt. Modding for you. More answers here.

[OKJEFF4]

I hooked up my very cheap cathode to my PC Toys Rheo, it worked just fine. But, the inverter is combined with the unit, and it's VERY cheap.

[RadiationMan]

I would think it would be like putting a fluorescent light on a dimmer switch.

[vonkaar]

It depends on the inverter... many common CCFL kits will fire at 5v, but it will either be incredibly dim, on one end only, or both. Around 7v, the whole tube should be lit, but very dim. From 7 to 10v, it increases in brightness until you can't tell much of a difference between 10v and 12v. If you have a 12v potentiometer that can channel enough current, you should be able to manually set your CCFL brightness. I would look for a mutli-turn pot so you can fine tune brightness.

Macroman at Bit-Tech designed a throbber circuit that I'm using for an automated throbbing effect.
Click here (http://www.bit-tech.net/article/78/) for information.