I already tried frex and a dozen other software generators.
Without amplifier and wave corrector it seem useless. I have not seen any effect from pc generated frequencies.
Most have to work with square waves, and limited to the audio range, this make them only suitable for the less effective Crane frequencies.
Rob
I think a GB4000 even with amplifier is not strong enough to use a gas tube or bulb.
It is meant as a contact pad device, and for that the amplifier gives enough power, because there is minimal loss of power if it is directly aplied to the body.