To generate the high voltage required to start lasing within the tube, I connected 200x 9V ‘dead’ batteries together, this generates nearly 2000V across the laser tube. I’ve been collecting these batteries for months, you can use old batteries for this because they only need to provide power for a fraction of a second, this is enough to generate a short pulse of laser light.
Normally the input would be switched at 2Khz to generate a continuous output from the tube, but making a switching circuit from a DC power supply (a battery) involves some complicated electronics, this stack of 9V batteries is a quick way to produce the high voltage, low current required to activate the tube.
Even with these short pulses of light the tube can heat up quickly so I installed a small 6W water pump to push water through the cooling jacket. The pump is not very good at drawing a vacuum so the reservoir was stored above the pump so it could gravity feed. The pump was powerful enough to push a sensible amount of flow around the tube and back into the bottle.
Project info at Just Add Sharks site.
Check out the video after the break.