Certainly a Tacho generator will do the job. It is best transducer for RPM measurement
Techo meter is a generator which when connected with some revolving shaft..it will provide you voltage (0.7v per 1000rpm).caliberated instruments will provide you the rpm reading this voltage
Small meters cost almost 20$
while for diesel engine models etc it may be more then 50$.
But sorry to say i have no experience of bying it..i just used it in lab with 3-phase induction motors.
Esmaeli,
There are numerous ways to measure the rotation speed of a motor.
The advantages of each method critically depend on;
a) your budget
b) the desired accuracy
c) the scale and speed of the motor.
(I'll presume that this is a DC motor)
Note, if you *very* accurately measure the current and voltage across the motor then it is entirely possible that you'll see some harmonic content that is related to the shaft rotation. But I wouldn't do this - far too fiddly, prone to error, and wear in the bushes is not something that should be relied upon.
No, I'd keep it simple. An optical or magnetic pick-up and a simple frequency to voltage chip and you then have an analogue value that is both robust, can be calibrated, and is cheap.
I've used beam-break opto-couplers on shafts, and am presently exploring Avago's magnetic sensors ($7 and 16 bits of absolute rotation sensing!)
But you want rotation speed, not shaft angle.
Well, about 15 years ago, for my PhD I simply glued some bar magnets on to the rim of the disc I wanted the speed of. A reed switch, a few resistors, a 5V rail, and a very basic ADC, all gave me a rotation sensor good from 0 up to 10 revs per second at almost no cost and time penalty.
Make a better job of it, or even better, buy a dedicated sensor, and you'll have something for your purpose.
Whatever that is.
More details would be nice (shaft speed, size, environment, etc.
How about this?
http://www.ebay.com/itm/Professional-Digital-Laser-Photo-Tachometer-Non-Contact-RPM-Tester-Tach-Meter-/141060453750?pt=LH_DefaultDomain_0&hash=item20d7dbb576
It uses the reflected beam from a laser to determine the absence/presence of a blade. Very reliable. Solid state, a sure win. Cheap too!
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