Measuring Wind speed Using Fan and IR sensor

[ranakashif]

Hi,
I want to measure wind speed using a simple fan and IR sensor.The output of IR sensor is 0 and 5V.I used a slit having 20 wholes in it.I have programmed in mikroC. When I rotate the fan with hand sped changes but at rest speed is constant which is 53 m/s. I thing there is some thing missing.Kindly help me in this.

 

[andre_luis]

It is not necessary an optical apparatus for achieve that. There are fan models available with 3 wires: two for motor supply, but another one acting as an internal tachometer ( output open collector ). The purpose of such feature is the ability to evaluate the "health" of the fan, that due to being exposed to dust, often reduce spin rate, or even stops.

Probably you will need to take a research on a manner to cut off supply of internal motor, leaving energized only the circuit responsible to measure rotation.

Another issue necessary to check is if the wind is strong enough to move the propeller of the fan.




+++

 

[kam1787]

have to see your code

maybe you are reading AC mains cycles
-what lighting are you using?
-what is the power supply?

 

[ranakashif]

I am using CCP module of pic 16f877A. measuring frequency then converting it to angular speed.I am using TMR1 module of pic16f877A and mikroC for coding.