daedalusminos wrote:I'd be interested to know if you plan to keep the LED's on permanently and log when a direction change occurs though the phototransistors, or are you planning on sampling the phototransitors every so often and log the direction at each sample interval. If the latter, what sample interval are you proposing to use?
I'm planning on having the LEDs on continuously and reading the PTs something like every 3 or 10 seconds. I haven't decided how often to sample. For the anemometer I'm thinking of something like a few seconds to catch gusts but I think the wind direction could be sampled less often - not sure. I might try to build in some sort of averaging for the wind direction in the software, in which case more frequent sampling could be an advantage.
I've always planned to have battery powered sensors (probably with solar top up charging) but I still need to keep current draw to a minimum. The hall sensor I'm using draws approx 15mA whilst measuring so I need to shut this down and power up momentarily to take a reading, but I'm wondering what sample interval is realistic?
Hmm... yes. 15mA is quite a lot for battery power. I have been thinking of the possibility of using intermittent power for the LEDs. I could add a 1-wire PIO chip to switch the LED power - they're well up to the job. Makes the software slightly more complicated, of course, because I'd have to power-up, read data then power-down. Not that difficult and may be the way to go. I could then use 1-wire parasitic power and a large electric capacitor (or a battery).
So many ideas and ways of doing things!