This is a very simple set up that anyone can put together shortly after getting the parts. It works as well as the expensive units costing $500 or more but it costs only about $25. A good source for the transformer is a shop that repairs or installs neon signs. You can usually pick up a used one for next to nothing.
First you need a neon sign or similar transformer at about 6000v., small glass jar and a larger jar that will hold the smaller one. The larger jar can be glass or plastic, the smaller one should be glass. You need a small amount of aluminum foil and a few short pieces of wire. The transformer can be as small as 3000v. You can use up to 15000v. Put a piece of aluminum foil inside the small jar at the bottom. Cover the outside bottom of the small jar with foil so that it covers the same area as the foil inside. Make sure the inner and outer foil layers do not touch or come too close. Put the smaller jar inside the larger one. Connect one high voltage lead to the foil inside and the other to the foil outside. A paper clip will work for the connector. The larger jar just insulates the whole thing. Put the whole set up on a piece of wood or some kind of insulator. Do not to cross the wires. The bare part of the wire must touch the foil.
Turn it on, you'll hear a crackling noise and if its dark you'll see a blue or greenish blue glow. If there's a short you may see an arc, just turn it off and separate the conductors so that they don't short out. A short will have more of a red or orange glow. The ozone will come out the top so don't plug it up. Ozone is a very powerful deodorizer it also tends to kill mold and bacteria but will not harm your plants in small amounts. Try not to breath a lot of it. Its not supposed to be dangerous in small amounts but is an irritant. Run it at the beginning of the dark period with a timer. Two hours per day is enough but that will depend on your odor problem.
Growquest put together one of these and here are a couple photos of it. He used a variation of the glass jar technique and used a piece of glass with wire mesh on both sides. He used hot glue to put it together and set the slab of glass upright on a piece of wood. The wood provides insulation. In the image on the left you see the alligator clips he used to connect the high voltage with. The other side of the glass sheet has another piece of mesh just like this one. In the image on the right you see a close up of the wire mesh.