If you mean to find the alternator or Induction Motor rotation speed in RPM...then use the following formula.
Ns = (120 xf) / P
Where
Ns = Synchronous Speed in RPM
f = AC Frequency..may be 60 or 50 Hz
P = Number of Poles.
Thanks
If you mean to find the alternator or Induction Motor rotation speed in RPM...then use the following formula.
Ns = (120 xf) / P
Where
Ns = Synchronous Speed in RPM
f = AC Frequency..may be 60 or 50 Hz
P = Number of Poles.
Thanks
ANY object? A bicycle wheel is quite different from a jet turbine which is quite different from dentist's drill. If you have a specific thing in mind, tell us. There is no universal answer.
ANY object? A bicycle wheel is quite different from a jet turbine which is quite different from dentist's drill. If you have a specific thing in mind, tell us. There is no universal answer.
The easiest way to do that is to buy a magnetic sensor that is used by commercial bike computers. It is a reed switch that closes every time a magnet on the spokes passes by. Use the reed switch to make a logic signal that pulses every time the switch closes. Connect those pulses to the 8051 and meausure the time in microseconds between pulses using an input capture peripheral. From that it is easy to calculate the RPM.
As Tunelabguy said before, you can also use a Hall Efect sensor, of course you must have a magnet on some place of the wheel, there are many types of Hall Efect sensors, for your application would be better to use one with Digital output. Search internet for Hall Efect Sensors. Yosmany325.
As Tunelabguy said before, you can also use a Hall Efect sensor, of course you must have a magnet on some place of the wheel, there are many types of Hall Efect sensors, for your application would be better to use one with Digital output. Search internet for Hall Efect Sensors. Yosmany325.
Magnetic reed switches are cheaper than hall-effect sensors, and don't require any power. That's why they are always used on commercial bike speedometers.
use a strobo scope , the chinease one is about 200$ , it can detect speeds from zero rpm to 10000rpm
this device emits light on and off in a very fast way , you vary the nob until you see the motor shaft (appears to be)not moving , and you read the rpm from the device.
very easy to use and accurate , and u can builld ur own ( i have seen similar projects by arduino)