Cyclocomputer Sensor & Anemometer

Hy guys, good work here!!! I've an issue to build a sensor for the magnet of a computerbike.. How i have to proceed? I hope i have to connect a solenoid to the computer.. ?

Topic by Gargiuseppe 11 years ago  |  last reply 11 years ago


Anemometer and the diameter vs circumference

Various Instructables have been created for building a wind speed anemometer, and nearly all use a bicycle speedometer for the read out. My question is, regardless of the actual diameter, the sensor can be close to the outer rim, or close to the hub, because one revolution is going to be one revolution and register as such on the speedometer. So, setting the speedometer to whatever rim size you desire, the readout would be correct. If you set the tire size to 24", then each time the sensor is tripped, it will show the speed for that tire size.  The same with 27" or 28" tires. The reason I'm asking is because I'm putting together a 'gopher chaser' from Harbor Freight (on sale last weekend for $1.50) which measures 17 3/8". I have no desire to cut new blades from sheet metal.... Thanks for any input on the issue.

Topic by GrumpyOldGoat 8 years ago  |  last reply 8 years ago


What is the maximum velocity that could detect the optical sensor of a mouse?

I'm planning to do an anemometer passing a cilinder over the light and monitoring the velocity with software. Thanks in advance!

Question by aletoscano 9 years ago  |  last reply 9 years ago


Question Regarding Measurement of Vacuum Pump Air Flow Using Anemometer

Hello everyone, I am new to Instructables and am loving it so far. I was reading through some literature on a piece of equipment we have at work and it requires 18"Hg @ 25CFM. We have flow gauges at work, so it is just a matter of using one to determine the flow but it got me thinking... What is the most effective method of measuring airflow of a vacuum pump without a flow gauge. All I have is an anemometer, a basic understanding of physics and time. So I came up with this method and am looking for some folks to poke holes in it: I placed the anemometer at the end of a 36" piece of PVC with a 1.6" I.D. sealing the anemometer to the PVC to ensure no air gets pulled around the fan of the anemometer. The other end of the pipe is reduced to a 1/4" line (.16" I.D.) which is connected to the vacuum pump. Turning on the vacuum pump yields a steady 3.5MPH (307.98 ft/m)on the anemometer. Doing the math, I come up with 4.3CFM (307.98ft/m*.013962634ft^2).  Unfortunately, I cannot bring a gauge home from work to compare and I cannot bring my set up, as glorious as it may be. So this is more a thinking exercise. So what sort of accuracy would you guys think this 'rig' has? Can you think of some method for me to verify it's accuracy (or, more likely, lack thereof)?

Topic by mmcdonald6 8 years ago  |  last reply 8 years ago


RPM/MPH formula

I'm designing an anemometer with Arduino and I need a formula to figure out the speed at which the rotor turns. I have a rotor with three magnets, spaced 71mm apart, triggering a Hall Effect sensor which the Arduino reads and counts. Now I can't seem to figure out a formula to calculate wind speed from this information. Anybody got an Idea (or the answer?)

Topic by smkoberg 8 years ago  |  last reply 8 years ago



Low-tech anemometer that records highest wind speed

I've been tooling for one of these for ages, or how to build one. It has to be low-tech: no electronics, no batteries if at all possible. I want to measure the highest-speed winds per day, not the actual windspeed at that particular moment. I live in a wind-tunnel and I'm curious to know just how strongly it blows My very vague idea was: windsock with a cord attached to the far end gauge with vertical slider, wind speeds marked, sliding part fitted with ratchet system so it can move up freely, but not down again cord on the end of the sock connects to the back of the slider: theory: the harder the wind blows, the higher the end of sock will be lifted, and the higher the slider will be pulled. Each day I'd be able to take the highest reading, then reset the slider back down for the next day I've got a cheap cup anemometer but I've no idea how to use its rotation speed to make measurements of course, marking the gauge accurately would be a bit tricky! Does anyone have any thoughts/tips/suggestions? Thanks! I've been looking vainly for "mechanical anemometers" but usually get the "take four paper cups" type, or the pukka ones at £££ or $$$. it'd have to stay outside all the time, so a battery one wouldn't be much use

Question by HelenaTroy 6 months ago