Taking pulses off Fine Offset wind speed sensor on Windmill

[Stuart2007]

I have a Fine Offset running Cumulus. So far, very good!

Next, I want to log the pulses from the wind sensor onto a secondary logging system so the wind speed can be recorded (via an arduino) onto an SD card with other concurrent data, particularly, how fast the sweeps are turning on the windmill.

To avoid loading up the input of the FO transmitter, I am planning to use an op-amp as a voltage-follower to drive the arduino.

Has anyone tried anything like this? I can't just put up a second FO wind sensor as there is no room on the mast on the back of the windmill.

Thanks

Stuart

[AllyCat]

Hi Stuart,

Personally I wouldn't use an Op Amp, a simple CMOS buffer or inverter would be better. But you shouldn't really need to buffer a normal logic input at all, just use a limiting resistor of some kohms for protection.

The FO transmitter feeds out about 20uA to the anemometer magnetic reed switch and the voltage swing is from about 3 volts (2 x AA cells) down to ground (with very low resistance) when the reed closes. The main thing to avoid is pulling the anemeometer voltage higher than 3 volts (which might feed current back into the transmitter). Most normal logic inputs switch at about 1.2 - 1.4 volts (except some CMOS devices which switch at half of their supply rail voltage).

Cheers, Alan.

[Stuart2007]

Alan

Great info, thank you.

Stuart