My background is in Physics and Electronics so lately I've been toying around with the idea of creating a "Jacob's Ladder", and perhaps making it battery operated so that it may be portable enough to take on investigations.
I found some various plans for doing this (and mind you this is NOT recommended unless you know what you're doing). Most of the plans include using a 12Kv Neon sign transformer. Now obviously this would make it far from portable since it would require 110v to operate.
The alternative is to use a fly-back transformer from an old TV or monitor. This could possibly be powered by a 12 volt battery and some circuitry to generate a 18-30khz AC source. This high frequency power source could then be modulated with lower audio frequencies.
The ultimate goal being to pump energy into the air which spirits can use to manifest. Of course this could be a double edged sword. And would also carry the added danger of having a high voltage low current exposed power source. (Shock hazard)
I'm curious if any of the investigators in our network have tried this yet. If not, it may be worth a shot.