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InaMORAta: Difference between revisions
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Most case fans have a tachometer inside, using the third wire to send its signal. It will be strobed once for every two revolutions. If it is e.g. strobed 80 times within a second, then there were 160 revolutions in that second, and we can extrapolate to 9600RPM (truly an insane case fan; I know of no such monstrosities). | Most case fans have a tachometer inside, using the third wire to send its signal. It will be strobed once for every two revolutions. If it is e.g. strobed 80 times within a second, then there were 160 revolutions in that second, and we can extrapolate to 9600RPM (truly an insane case fan; I know of no such monstrosities). | ||
We'll need a digital input pin with interrupt support. On the Arduino Uno, this restricts us to pin 2 or 3. | We'll need a digital input pin with interrupt support. On the Arduino Uno, this restricts us to pin 2 or 3. We use pin 2, plus the necessary resistor. | ||
==Control (PWM)== | ==Control (PWM)== | ||
