• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

hooking up a rheostat to control cc tube brightness?

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.


All that is Man!
Nov 24, 2001
Stillwater, Oklahoma
you have to remember, that the inverter runs at 12 volts, but the actual cathode runs at something like 200 volts (not sure the exact rating)

i would not mess with the cathode intensity. thats why they gave you an on/off switch. i think its just too much to worry about when you mess with that high of voltage in your computer, at least regulating it.


Senior Overclocking Magus
Feb 26, 2003
Adjusting the votage going into the inverter would likely just cause the Cathode tube to not light up.

I guess you could just try sticking a Potentiometer (Variable Resistor) in front of the wire leading to the inverter, and see what happens when you adjust the resistance!

Trying to regulate what comes out of the inverter would be dangerous, for th reasons RangerJoe outlined.


Aug 13, 2001
Bergen, Norway
No problem!

I'm running mine with a throbber, fading 4 CC tubes in and out (two inverters). As long as you only work on the 12V side you should be fine, at least with all modern inverters. Some old types WILL burn when voltage is altered, but most modern ones work just fine. Also 7V works fine.

As for how it is done, it depends on the wattage drawn. Most reostats get very expensive if the handle a couple of watts, and the CC can draw a bit of power. So, I'd rather try a LM317T based controler. Cheap and easy, with a lot of power.

PWM is no good as the electronics inside the inverter may "freak out" with rapid on/off.

Also, the effect is dependent of the tube involved. Long (30cm) tubes tend to dim smoothly before the light "looses the end" and only lights halfway down the tube. Short tubes (10cm) tend to dim very suddenly from full brightness to much weaker.

..but I guess it's all down to inverters, tube and luck..