and another one question. Can the current that is produced by the motor to make a wave with frequency analogical to the current? i find more difficult the idea about hall effect or IR detector to built it ( the construction ).

 

The above solution was an analog approach and requires a knowledge of electronics you probably don't have. And besides that there is probably an easier digital solution. Not only that but your teacher is probably forcing you to think about the problem in terms of that initial 1000 Hz. I doubt very much he or she wants you to just add the pulses from the transducer to 1000. That would be a gimmick to meet the design criterea. I'll be thinking about it. I'm drawing blanks right now. In fact, even the analog solution above was gimmicky like that. Whatever the soluton is, it requires a transducer that creates frequency with respect to wind speed. Perhaps air pressure is the key? I mean like some sort of pressure sensor that creates a voltage using a strain guage then using that voltage to operate a voltage controlled oscillator. Food for thought. Good luck!

 

Thank you very much for your help. This project is not for any teacher or for school. I just want to make a cirquit to measure the wind speed. Are there pressure sensors that can measure so small pressures like wind's? And the 1KHz frequency was an example for the drawing. I want to be just a frequency in the human audable range ( 20Hz - 20 KHz) . When i started thinking of the project , i had in my mind an analog output, but i don't think there will be any problem if it is digital.

 

If the 1kHz thing is not needed (a pain in the neck) then forget it. Just make a fanlike thing that turns in the wind easily. Put a magnet on the tip of each "blade" and have those magnets pass very close to a coil of magnetic wire wrapped around a ferric core. This will induce a small current in the wire. Treat it as a small signal and amplify it. Now you have pulses you can count. But if you're not worrying about counting pulses, if you just want an audio signal that has a frequency of 1kHz when no wind is blowing (so people can hear it) then use those pulses to feed a computer that can count them. Then use that value to compute an output in the form of a binary number (0=1kHz) into a DAC. Then use the voltage output of the DAC to vary the voltage of a VCO (voltage controlled oscillator). Amplify that signal and feed it to a speaker.

This is the kind of project that requires hands on experimentation. Again, good luck to you. I think I now know what you want and I think I answered your question in a general way. If not let me know. In fact, if I did, let me know.

 

You have given me food for thinking and reading for a long time now... Thank you, i will try to solve my problem on the ideas you gave me, and for any new problem, i will write in the forum.

 

You have given me food for thinking and reading for a long time now... Thank you, i will try to solve my problem on the ideas you gave me, and for any new problem, i will write in the forum.

Before you go running off I would like to say something. Do you want to simply generate sound with its frequency proportional to the rotation speed of a muffin fan when wind is rotating it? If your answer is yes then simply use an AC muffin fan, Put two diodes across the leads and plug it into your PC's or amp's Mic jack.

 

Wow, it could be so easy to simply generate a sound with the frequency proportional to the rotation speed. Yes this maybe will do the same work that i want to do.

 

Basically you need this. Ignore the + on the motor.

 

Here is something to get you in the ball park.
I just breadboarded it and it works good for changing freq. sound with the turn of the motor shaft.
Also if you turn the motor backwards the freq. pitch drops too.
So you can make it increase in freq. and decrease according to shaft rotation.

EDIT the base resistor on the emitter follower going to ground needs to be 10K ohms NOT 2k.

 

what are the protection diodes. whet protection offer?

 

Here is something to get you in the ball park.
I just breadboarded it and it works good for changing freq. sound with the turn of the motor shaft.
Also if you turn the motor backwards the freq. pitch drops too.
So you can make it increase in freq. and decrease according to shaft rotation.

Thank you. Thats what i was searching for, from the begining. Simple and exactly what i was searching for i think.

 

what are the protection diodes. whet protection offer?

They prevent the input to the Mic jack from exceeding .7V. I did not employ a series current limiting resistor because these fans are HiZ.