Kind of a weird question... I don't have any cathodes available right now or I would test this myself. How fast can a cathode go from off to on to back off again? Here's what I am thinking... I am making a quite large VU meter (over 4 feet tall) and planning on using 4 or 6 inch cathodes as the lights, all controlled via a pic. I have a working concept with LEDs, but to supersize it like I want the price escalates to almost $400.
A few hundred times per second, though the very first turn-on might be a bit slower as you may have to charge some caps up in the inverter. Special inverters are sold with a switching connection point somewhere in the middle of the inverter circuitry, aimed at PWM control of brightness. But my cheapo CCFL lamp dimmed fine on a 200Hz PWM-switched 12V supply.
Gotcha. I appreciate the link, but all of those inverters are $23 or more! At 24 tubes x $25 cost becomes prohibitive ($600!). Considering I can buy a full dual cathode kit for $5.99, there has to be a cheaper solution...especially considering this is just for fun anyways. I wonder if I could just switch the power to the actual lamp, instead of switching the power to the inverter. That way the caps would stay charged all the time and I would still be able to rapidly cycle the power of the cathodes to get my VU meter working. Anyone see a problem with that? See, what I am thinking is similar to all the VU meters that you see with LEDs. There are hundreds of simple circuits on the internet to build one and I am just planning on adapting and...err...supersizing it. The intended application is to be run down the side of my car, partly as a joke, partly to piss off a buddy that has "more kick ass lights and sound" then me.
Several hundred volts. Plus the length and electrical properties (capacitance mainly) of the lamp supply lead are critical. In an audio bargraph I don't think switch-on delay will be a problem, just switch the 12V supply.
