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Cathodes on a Rheostat?

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Foxie3a

Normal Member
Joined
Sep 7, 2003
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

Member
Joined
Mar 10, 2003
Location
MA
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
 
OP
Foxie3a

Foxie3a

Normal Member
Joined
Sep 7, 2003
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

Just Freeze It
Joined
Mar 11, 2003
@0watts for a channel is VERY good for a rheo. The sunbeam has that, but most others have anywhere from 8-13.
 

L337 M33P

Member
Joined
Jun 5, 2003
Location
TEH INTERNETS
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.
 
OP
Foxie3a

Foxie3a

Normal Member
Joined
Sep 7, 2003
how about the PC TOYS ones..cause those are very cheap.. :-D
 
OP
Foxie3a

Foxie3a

Normal Member
Joined
Sep 7, 2003
can I throw them onto a switch so they go on and off? :)
 

L337 M33P

Member
Joined
Jun 5, 2003
Location
TEH INTERNETS
Yes - you just can't control their brightness unless the inverter is adjustable, that's all. Switches will probably work fine.
 

donny_paycheck

Inactive Super Quad Mod
Joined
Oct 25, 2001
L337 M33P said:
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

Member
Joined
Jan 9, 2003
Location
Sapulpa, OK
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.
 

vonkaar

Member
Joined
May 20, 2003
Location
Colleyville, TX
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 for information.