Anemometer recommendation please

Hi all,

The anemometer on my weather station has failed again. It's the third replacement. The bearings fail after a couple of winters.


While Maplin were still around, I could get replacements for < £5 including postage from them on eBay. Now, I would be looking at 3 times that price, and it's just not worth it.

So I'm looking into a more robust replacement. There are a few models around £30 on eBay. Some have pulse output, some have voltage output, some have 4-20mA current output. They all seem to have quite high voltage requirements and I don't know if they are very power efficient for battery operation.

The anemometer shown above contained a simple magnet and reed switch. I was able to use an Arduino output pin to provide a pull-up to 3.3V to an input pin with the reed switch from the input pin to ground. That way, I could switch on the pull-up for a couple of microseconds while reading the input, every 1ms, and this minimised the current used down to an acceptable level.

So I'm looking for recommendations for a reasonably priced but more robust replacement, better quality plastic or aluminium or whatever, which I can achieve a low power method of reading, for a battery powered (3.7V li-ion or 3xAA NiMh) weather station.

Here is my old weather station. I want to start over with the whole design, using perhaps atmega328 and LoRa instead of Wemos.

Does anyone have any thoughts, suggestions or insights for me?


Alternatively, I could attempt to replace the bearing in my existing sensor.

I don't know anything about bearings. How can I identify the size/model required? The bearing appears to be 10mm outer diameter.

Got the bearing out. It's 10mm outer diameter, 5mm inner diameter and 4mm deep.

Can anyone advise if these would be a suitable replacement? They're stainless, so I'm hoping they will outlast the originals.

I would look for a an ultra low torque bearing that can be re-lubricated. Take it down yearly, check for free wheeling and re-lube. The type I'm thinking about have a felt wick on one side and are lubed by a light oil instead of grease.

Thanks for the advice. That sounds pretty specialist, certainly couldn't find any on eBay anyway. The nearest I found was these, but I don't think they are stainless.

I've ordered a couple of those stainless ones, will report back how well they seem to work.

The design of the rotating part is the problem. It does not cover the base part and lets the rain and dust enter under it. You need to extend the rim downward to completely cover the base part. PVC pipe piece might work.


That bearing is a SMR105-ZZ.
Don't know what country you are in, but her are a couple.

You can get them a lot cheaper from China if you want to wait.

A little hint. Most bearing will have a number on them, which if you go to a bearing supplier such as the one in the first link you can search that number.
Most of them also let you search by the dimensions.
Another thing I noticed is your bearing looks like a metal shield type which are not real great for keeping out moisture and crud.
A better choice would be a rubber seal type. The only downside is they have more drag than the metal shield bearings and they are harder to find.
They stock them at VXB in the first link.

Hope this helps.

How about ultrasound based anemometers? No moving parts to go bad. Won't come cheap I'm afraid.

Won’t come cheap I’m afraid.

You put your finger on it there.

The replacement bearings I purchased (link above in post #3) arrived, I used them to repair my anemometer and the spare and have deployed one and it seems to be working as good as new. Problem solved for now. But I would still be interested to learn about other anemometers that other forum members have purchased and their opinions and findings about robustness and power consumption.

This is my anemometer except mine has hdpe cups and their connecting arms. Could be a prototype or? Got it for $10 at a ham radio/electronics swap meet several years ago.

Has worked flawlessly for 3-4 years. Use with Nano and 2-line LCD. Run about 50 feet of tiny shielded wire between the two.


Thanks Paul. Sounds like your sensor is also a magnet and reed switch with no other built-in circuitry.

Thanks Paul. Sounds like your sensor is also a magnet and reed switch with no other built-in circuitry.

Exactly! The bar magnet is rotated directly above the glass reed switch so twice per revolution the magnet is exactly parallel to the reeds and twice it is 90 degrees to the reeds.

There are two bearings on the shaft between the cup assembly and the magnet. All protected from the elements.


Can anyone advise if these would be a suitable replacement? They're stainless, so I'm hoping they will outlast the originals.

Search for "5mm full ceramic" bearing.
They can run dry and aren't affected by water as there's nothing to corrode.
I've used the ZrO2 variety for a DIY salt water flow meter which has been running for over a year.
Typically they don't have contact seals so the stiction is low which helps with the linearity at low speeds.

I was just about to say this is the perfect use of a ceramic bearing, but I've been pipped to the post. Far tougher than steel, water not an issue, will work dry though a little light oil or teflon spray won't hurt.

Thanks all. When these stainless steel bearings fail, if the plastic hasn't crumbled, ceramic bearings it is.