THE "POOR-MANs" (junk-box) ANEMOMETER

2-24-01

By Gregory Tatlock, N9PUG

When I started this project, I already had a Davis weather station, but wanted to design and build one as cheaply as possible for a friend of mine, Alvin, KA9QLQ, who is disabled. I wanted to be able to use parts that were readily available to 95% of most hams, and be able to do it in such a way that everyone could build one without having to have a college degree. I also want to thank another ham for his input, and that is Jack Demaree, WB9OTX. Well, here goes the rundown, it is simple. I used a AOL cd for the rotor, a small dc motor, this one was out of a handheld fan that used 2 AAA batts, the meter is from a old CB, and just for demonstration purposes only, the mount is from regular PVC, but this is not the permanent mount. The only part of this that is not from the junk box, is a blade adapter from a hobby shop. This adapter changes a prop from a gas engine size drive shaft to an electric motor, Check Tower Hobbies or your favorite hobby shop, or make your own, but make sure to use aluminum or light weight material.

The cups to catch the wind are from pill bottles, the ones I used are 1.75" diameter, and seem to work well with the diameter of the disc. The holes in the disc are spaced 104mm apart, I will give you that info and save you some time on trying to figure out the proper spacing. All that has to be done is to solder your wire onto the motor leads , almost any kind will do, I used telephone wire on one, and on the second one, used wire form an old Motrac. The way I attached the cups to the disc was some very small screws, also from the Motrac, but would also recommend a small amount of silicone to help keep them in place. You will have to determine for yourself the size of PVC to use after you find your motor. Connect the wires to your meter, dont solder yet, make sure you have the proper rotation in conjunction with the meter. I used heat shrink on the shaft of the motor to help secure it in the blade adapter. The blade adapter comes with a compression washer, and when this is turned upside down, it not only helps to secure your disc, but also centers it!

Now, here comes the work. How do you calibrate it?? You can do it one of several ways. Since I already had a calibrated anemometer, I mounted mine within 2' of it, and with a good steady wind, was able to mark the meter and label it with 5, 10, etc. Another way is to mount it to the bumper of the car, drive 5, 10 etc and mark it. DONT do this by yourself!! Most meters will come apart, and can be repainted or marked to reflect wind veloscity. Also, a variable cap can be put in line to help with calibration if needed.

Well, thats about it, simple, fun and pretty darn accurate, and best of all, you will probably have less than five bucks in it. Dont forget to seal up all holes or the bugs and bees will have a new home. Enjoy.......

de Greg, 73's