Run CCFL w/ audio sig?

Question

I would like to power a fluorescent or CCFL tube with music tracks (at stepped up voltage) instead of the usual fixed frequency output of standard inverters.

For this experiment I would use a small 8W flourescent tube or a 370mA CCFL.

Is it sufficient to apply HVAC audio from a step-up transformer?

How would I deal with the necessity of a higher strike voltage? Or .... how long would the lamp last if I simply used the strike voltage for continuous operation?

I only need a few hours operation here to prove a principle.

If there is a more suitable plasma source for this application, I am open to suggestions.

Maybe something based on a HVDC laser supply.

Thank you,

James

Tim Wescott · Accepted Answer

Florescent lamps driven by constant-voltage supplies don't last very long at all -- they have steep negative resistance slopes from the strike voltage down to the operating voltage; attempting to drive them at the strike voltage will destroy them in very short order.

Florescent lamps driven by constant-current sources change their power output as a function of temperature (it's a positive tempco), and their temperature as a function of power output. So just controlling current to the lamp will not necessarily get what you want.

Automotive high-intensity lamps achieve instant-on performance by using a constant-power supply that monitors voltage and controls current to hold power relatively constant. This will require a fairly fancy switching supply, but at least 8W is doable. I'd start there. I suspect that there will be a range of power that is achievable, but I have absolutely no idea of how wide it is.

James Meyer · Answer

On Thu, 27 Jan 2005 15:56:29 +1100, James King wroth:

Running the tube supply at a fixed frequency higher than the highest audio frequency of interest and "closing the loop" around the system by comparing the audio input to the light output might be the way to go. You haven't said exactly what you want to achive though.

Jim

James King · Answer