- #1
SentinelAeon
- 31
- 3
I have a table fan and i need to compare it's rpm in 2 scenarios. Its a big fan with 3 blades. Since i don't have any fancy tools or specs, i thought i could get an approximation by using mobile phone and a stop watch.
My plan would be painting a black dot on 1 of the blades. Next to a fan, i would put a stop watch and start it. I would point my mobile phone at fan and stop watch and record a video with my phone at 60 frames per second. Then i would playback the video at a slower playback speed. I would skip frame until i see the blade with black dot pointing upwards. I would note the time on stop watch. Then i would slowly play forward and count how many times the dotted blade is pointing upwards. I would stop when 5 seconds have passed on a stop watch. Then i would multiply the number i got by 12.
The reason i included a stop watch in this plan is to make sure that my mobile phone really is recording at 60 frames per second and not doing something wrong. If 5 seconds passed on stop watch also means 5 seconds passed in my video, i can be sure its all ok. If i wanted a better result i would measure for more than 5 seconds.
Would this be a good way to get an approximation without special tools ?
My plan would be painting a black dot on 1 of the blades. Next to a fan, i would put a stop watch and start it. I would point my mobile phone at fan and stop watch and record a video with my phone at 60 frames per second. Then i would playback the video at a slower playback speed. I would skip frame until i see the blade with black dot pointing upwards. I would note the time on stop watch. Then i would slowly play forward and count how many times the dotted blade is pointing upwards. I would stop when 5 seconds have passed on a stop watch. Then i would multiply the number i got by 12.
The reason i included a stop watch in this plan is to make sure that my mobile phone really is recording at 60 frames per second and not doing something wrong. If 5 seconds passed on stop watch also means 5 seconds passed in my video, i can be sure its all ok. If i wanted a better result i would measure for more than 5 seconds.
Would this be a good way to get an approximation without special tools ?