Squarewave modulate CFL

[Les Crane]

I would like to modify the inverter circuitry within a 12V powered
compact fluorescent lamp (8W) to accept squarewave modulation in the
range of 100Hz-10KHz.

What is the best method for doing this, and where within the circuit,
so that the tube is not damaged?

Les Crane

 

[whit3rd]

I would like to modify the inverter circuitry within a 12V powered
compact fluorescent lamp (8W) to accept squarewave modulation in the
range of 100Hz-10KHz.

The inverter must free-run to produce a stable output, so you can't
modulate
it at all. What you CAN do is to shunt current around the tube into
a secondary channel of some sort. The drive is probably AC, so
you'll want to use a diode bridge to make a DC switch point, and
the easiest device to switch these low currents and high voltages
might be a vacuum tube.

There will be severe difficulties in the under-1 kHz range if you
actually
quench the arc inside the lamp, because initiation times are
uncertain.
The inverter frequency will beat against your modulation, too.

Neon lamps light at lower voltages, and can be run on DC, so
are often used for this kind of modulated light source. I've seen
neon lamp/rotating disk devices that do realtime Fourier analysis,
so you could calibrate a musical instrument, about 1950 era.