OK, time for an experiment.

I hooked the secondary of a small power transformer up to the speaker outputs of an audio amp. The primary went to an indiglo nightlight and a scope.

Into the amp I fed the output of my notebook running a test tone generator.

This gave me a 10Hz to 20KHz, 0-330Vac source. (Much lower voltages at either end, the top limited by the low frequency transformer, the extreme lower by the amp.)

It worked! (I tried not to look surprised.) At the lower end the glow was quite deep green. As the frequency increased it went through cyan to deep blue. Most of the transition happened between 500Hz and 5KHz.

So, while the dopeant certainly controls the color, the frequency does have some impact too.

Getting back on topic, it appears both blue and green could be covered by the same buttons. I'm not saying that this is a *suitable* light source but there is room for tweaking it at least.