I recently bought this ozone generator (enaly OZX-300AT - 220 volt version) of ebay - it uses 2x 4" long stainless tubes acting as anode/cathode - one inside the other. The air is pumped into the gap between these tubes exiting on the left outlet.
There is no forced cooling on this unit & the transformer is is small cast iron horseshoe design.
Ive posted this because Im interested in the design and may be helpful for others looking at buying a cheap ozone generator (cost me £55 new) and would at some stage like to build my own based on a cold cathode oxygen fed design after reading through this and Hv's forum.
So far, I'm getting a lot of use out of this generator and its proving reliable. Its great for ozonating water and disinfecting appliances, clearing odors from rooms, cars and deodorizing footwear and clothing and I love the smell that remains afterwards - concentrated fresh air!
could do with a more powerful unit though!
The downsides to this unit is that it uses lots of plastic & pvc tubing rather than silicon tube , the pump is one speed - a variable speed pump would be more useful.
That is a problem with these units. The pumps they use are not piston pumps but rather diaphragm pumps. The diaphragms generally don't last long, especially when exposed to the ozone such as the ozone in the air that gets sucked in to the pump. The good news though is that the diaphragms are easy to replace. Take the old diaphragm with you to an aquarium store since you will need to match up the diaphragm for that pump. Otherwise it is just as easy to take the pump out and use an external pump or small compressor set to a low pressure.