View Full Version : Any way to make a PC bulb only half light up?

07/08/2010, 04:29 PM
I ordered two PC bulbs for my tank one actinic and one 50 50.
The white in the 50 50 takes over the blue way more than i expected.

I dont need the full 200ish watts of light from these bulbs due to my MHs so instead of spending more on a new bulb I was wondering if I could make only half of the 50/50 bulb light up just so the lighting doesnt look uneven.

I figure maybe only plugging in 2 of the 4 prongs might do it (square pin)
but to avoid any potential disaster I figured I would ask first.

Also, I dont mind if I have to permanently disable the white side of the bulb by clipping pins, or drilling or any modifications like that.

If worst comes to worst I will tape off the side i need, and paint the rest with 1200 degree paint and let it cure.

07/08/2010, 04:51 PM
You can not only light half of the lamp. The PC lamp is one lamp. A fluorescent lamp has one cathode at each end the lamp. With a PC lamp both ends are on one side. You can think of it as a linear fluorescent lamp bent into a U. Once powered both sides will light to complete the circuit. Both sides share the same glow discharge.

07/08/2010, 04:54 PM
Yeah I was worried that that may be the case. Thought they might possibly be seperated due to the split output types.

So they have 4 pins in the same way that a straight tube has four pins, except that on the PC they are both on the same side?

Thank you :)

If I cant find someone interested in a brand new bulb locally I will isolate one side with coating.

07/08/2010, 05:12 PM
Yes that is correct. A PC lamp is really just a straight tube bent into a U shape. All 4 pins are then located at one side.