anemometer mechanism

Does it have to be mechanical, or could you use a hot wire anemometer - which heats a wire by passing a current through it, and then measures the cooling effect of the air passing over it in order to determine air speed. If you need pulses, you could presumably use the anemometer's voltage output to drive a voltage-controlled oscillator.

AIUI, hot wire anemometers form the basis of air mass flow meters used in car and truck engines - so you might find a suitable one at a breaker's yard. It might even have a pulse output!

Check out

David

I seem to remember a DIY design in the dim & distant past based on split ping pong balls and some SS hypodermic tube, various dia's silver soldered, with PTFE bearings housed in a brass 1/2 inch tube. Electrical pulses using one or more reed switches and a small magnet on the rotor. Try asking on NG uk.sci.weather, some of the old stagers may remember the description and refer you to the original publication. Cheers

I think you can get spares for the WM918 (Oregan Scientific) or WX200 (Tandy) automatic weather station. ISTR that the wind vane and anemometer assembly was =A340 to =A360. The wind vane output is from the= wiper of 360 deg potentiometer and the wind speed from a reed switch that closes once per revolution of the cups.

Try some of the weather station retailers.

I have a hand-held hot-wire one you can have for the P&P. It hasn't been used for some years, and the batteries leaked in the dim, distant past, but it worked the last time I used it and doubtless it can be tested before despatch.

You need to find some of the more specialized model shops. Or a yachting shop. Both hobbies need to know wind speed.

I think

BUT you can take a small electric motor and mount 4 half Ping-Pong balls on carbon fibre rods on top of it and count pulses if you want...if you use an AC motor like e.g. what's in a CD-ROM drive, you will get a nice

I'll leave the electronics to you.

ISTR that a hot wire anemometer was responsible for several F1 engine failures in the rain. They DON'T like the wet at all.

Mine came from Dallas Semiconductor

These are the people who make the "one wire" chips. As a trade-show promo some years ago, they made a batch of simple weather stations, based around their chipsets. There was so much demand that they kept producing them afterwards.

Not sure if they still have them, but it's worth a look. "One wire" is worth looking at anyway.

In article , vortex2 writes

Thanks to all, the Davis wind sensor from the above site looks just the thing (reed switch output giving 1 pulse per rev). It has to be fixed to a building roof so anything handheld is no good.

Maybe rip apart an old PC mouse. There are two slotted discs, running between an LED and a sensor. A bit of butchery and you have a pulse output.

Edwin Bath.

How about: Two or three half ping-pong balls Fix half-balls onto shafts which are attached to a hub that can rotate Get an old PC mouse from junk box Remove PCB Connect one rotor somehow to above shaft Use output from sensor for pulse train

Oh yes, then turn it upside down under a hat of some sort

Peter Scott

You could try some (or all) of the Dallas 1-wire weather station:

How about: Two or three half ping-pong balls Fix half-balls onto shafts which are attached to a hub that can rotate Get an old PC mouse from junk box Remove PCB Connect one rotor somehow to above shaft Use output from sensor for pulse train

Oh yes, then turn it upside down under a hat of some sort

Peter Scott