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Lately I have been picking up "old" solar garden-lights for pennies. They drive a LED that uses ~3.5v. I have a small NiHe batt and some crude charge-control. Shouldnt this be just about right to drive a JeeNode (outdoors and in the summertime)? I saw the DIY soil-hymidity stick on Hackaday
http://hackaday.com/2010/03/15/soil-moisture-sensing/ and wonder if I can combine these parts.
Amazing work on the JeeNode project
Regard Mikkel
Yep - any 3.5..3.6 V source should be fine. The moisture sensor looks like a fun one to try out.
I was wrong about the gardenlight - it boosts out 3.5v in a square wave to the led - no good, but but..
I found the step-up converter @ Sparfun
http://www.sparkfun.com/commerce/productinfo.php?productsid=9216
It makes 3.3v max 100ma (enough?!). Hocked up to the 1,2v battery in the garden-light it should power the Jeenode until the end of days (or the battery gives up).
price 6 eur.
Normal gardenlight solar-panel gives up to 9ma (clear sun).
So a hacked gardenlight -> stepup -> Jeenode would seems to work.
A JN uses under 50 mA max (while the transmitter is on) - so yes, 100 mA should be enough. Just keep in mind that 3.3V @ 50 mA will draw some 150 mA from a 1.2V source - and that energy has to come from somewhere...
If I have understood you right - the node sleeps 99% of the time and the draws 50ma in a burst, using ~ 0.3ma/h (1mwatt/h) in average. So if the low drop out (LDO) regulator can deliver 50ma out and can idle using little, the solar-panel should be able to deliver for a 24/7 uptime.
On a cloudy day the solar-panel should give min. 1mA 12h (daytime).
The question seems to be how small a panel can be used to drive the JeenNode.
I found this one (3 eur :-): http://www.b2c-support.com/solar-power-3led-rechargeable-flashlight-torch-keychain-p-3655.html
Yep.