Variable Brightness Cathodes

Sushisource

K guys, electronics question for y'all

So, I just ordered my Antec 1200 and I'm about to rebuild my rig into its sweetest form ever. I'm planning on adding a variable brightness cathode setup. However, I don't know what kind of rheostat I should buy, and I want to make sure I do the wiring right so I don't blow any cathodes.

Here's what it should look like. Can you guys tell me if I should be adding any resistors and what type of rheostat I should buy?

The cathodes must not exceed 700mA. I want to regulate preferable between ~100mA and 700mA

CrystalMethodist

V = IR

12V = 700 mA * R

R = 17.14 Ohms

The resistance R will be equal to the sum of the resistance from the rheostat and whatever resistors you put in there (since they're in series). If the idea is that you adjust the current to adjust the brightness, then you can fix some amount of resistance r_1 from resistors and have the rheostat r_2 such that r_1 + r_2 is between ~17.14 and some higher number of Ohms.

This makes it so that the lowest setting on the rheostat is the smallest resistance at which you're pushing a safe current through the cathode, and the highest setting will produce some smaller current to dim out the light.

Sushisource

Excellent. That is what I thought but I just wanted to confirm. Thanks for the help.