How to measure the frequency of a AC sine wave signal?

Projects General Guidance
1

Hey guys,

I'm a Austrian student and I have to build a weather station.
From a little company i got a wind sensor for free.

The sensor is a YOUNG 03002 WIND SENTRY.
Manual: http://www.aicpl.com.au/pdf/ws03002man.pdf

The manual says that the output signal of the wind speed is a AC sine wave signal and the frequency of this signal is directly proportional to the speed of the wind.

So is it possible to measure the frequency with an Arduino Uno?

Thanks! :slight_smile:

2
3

Yeah i googled it a long time, but i have no idea how to connect the sensor?
I'm sorry that's all new for me...

4

First need to measure its voltage with a multimeter on AC range whilst you blow it at the minimum speed you expect to encounter.

If you get at least three volts, then you can connect it to the Arduino via a 47K resistor with diodes to ground and Vcc so that they only conduct if the voltage is greater than Vcc or less than ground.

If you get less voltage, you will need an amplifier.

5

Paul__B:
First need to measure its voltage with a multimeter on AC range whilst you blow it at the minimum speed you expect to encounter.

If you get at least three volts, then you can connect it to the Arduino via a 47K resistor with diodes to ground and Vcc so that they only conduct if the voltage is greater than Vcc or less than ground.

If you get less voltage, you will need an amplifier.

ok, and now?

6

http://lmgtfy.com/?q=measure+frenquency+arduino

Haw! That's cute as hell.

7

Data sheet says

AC sine wave signal induced by
rotating magnet on cup wheel shaft
100 mV p-p at 60 rpm. 6V p-p at
3600 rpm.

Yes, you need amplifier, here is a circuit base on transistor:
http://interface.khm.de/index.php/lab/experiments/arduino-frequency-counter-library/
6V is pretty high voltage for BJT, you would need to add two components:

  • resistor in series with input ( cap 100 n ), 1 - 10 kOHm should be o'k;
  • diode across base-emmiter of the BJT, 4148, 4007, practically any diode, to cancel negative halfwave.
    Other option - resistor + zener : http://ruggedcircuits.com/html/circuit_-27.html