With a Hot summer being predicted by the weather services, I thought I would pass on a remarkably effective way of cooling down an outdoor booth.

Begin by visiting a junkyard and asking for an electric radiator-cooling fan. They will want to know what kind of car you need it for, tell them it doesn't matter; you are just building a cooling fan and ask to see a few. Junk yards pull the radiators from old cars so they don't deteriorate, and the cooling fans come off at that point, so you will be able to see lots of models that have been already removed from the cars. Choose one that appeals to you and is cheap. You can also ask them to hook it up to a battery to check to see if it works, watch your fingers, the fans have powerful motors. It should run with out making grinding noises or too much vibration.

Next, you will need to build an enclosure. Measure from the front of the radiator cowling to the back of the motor. (The cowling acts as a scoop to direct the flow of air into or through the radiator). Visit a lumberyard and buy an 8-foot piece of 1" x 6" number two pine, like you would if you were building a shelf. If your cooling fan is deeper than 6" buy a 1" x 8" board, or what ever will give you the right depth. You will cut the board into 4 pieces to make the sides of the box the fan will fit into. (See my photo to see how I fit it together)

Screw the fan cowling into the wood box, and connect the two wires to a longer wire that you will connect to your battery. Since you are working with a low voltage, high amperage device, use at least 16-gauge wire. Heavy gauge two conductor speaker wire works well, and is quite flexible. Fix it to the sides of the box to keep it from getting in the way of the fan.

Now visit the hardware store and buy some wire screening. It should be stiff and have small enough holes to prevent anyone from putting a finger into the enclosure. I used quarter inch "hardware cloth". Cut the screening to cover both the front and back of the wooden box, and staple or screw it in place. You can add hooks if you want to hang the fan in your booth.

To run the fan, hook the wires up to the battery. Because this is a 12-volt direct current motor the direction it will spin depends on the way it is hooked to battery. If you reverse the wires the fan will blow the other way. Because of the cowling, only one direction will really move a lot of air. Mark the wires as to which should be hooked up to the positive or negative terminals to make the fan work in the most effective manor.

As to the life of the battery, that will depend on how big of a fan you get (one from a little radiator in a compact car will move less air, and run longer than one from a big car with a big radiator. Also, not all batteries have the same ampere-hour rating, bigger batteries will last longer. In my experience, an average size fan being run from an average size battery will last through an 8-hour show before needing to be recharged for the next day. If you run it only during the hottest hours of the show you could get several days use before having to recharge.

That's about it, if I was unclear on any of the details let me know.