>So, do you think this is a good method to measure all motor's speed amplitude >? From stall to highest speed ? This is indeed very interesting...
I think there may be difficulties for very low speeds, but in theory, I think you can not only measure the speed but you can actually count fractions of a rotation. With drawbacks, however. You'll have to filter out the PWM fraquency which would require a series resistor or inductor, and a (for reverse operation bipolar) capacitor. That will cost power that you might better want to save on battery-powered gadgets. I don't know however if filtering the PWM frequency is possible for the measuring only and leave the motor be powered directly by PWM. There wouldn't be much power wasted then. But, for theory, it's far easier to measure time or frequency accurately than anything else. A voltage reference (LP2950) costs 0.50, accuracy is 1%. A time reference (crystal) costs also 0.50, but accuracy is 0.005% or even better. If you need higher accuracy, there are radio stations around the world that transmit reference frequency standards (usually derived from rubidium clocks) at an accuracy of something like 0.000000005%. A reference of that quality, brought to your place for free, is unique for all measurable quantities. Enough wise-guying for today ;-) Greets, Kiste -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
