[werk_ag]

An alternative would be to use a DC/DC buck converter. The simplest way to implement this would be to use a module like the CUI V7809-500 (http://www.digikey.com/product-detail/en...ND/1828604), which is a drop-in replacement for the 7809, perhaps with some adjustments to the capacitor values. ...

Another alternative is using a 1€ DC/DC converter like this:



Wiring it to replace the 7809 is very easy.

I designed an Arduino-powered device a few years ago (specifically, a Teensy 2.0 (http://www.pjrc.com/teensy/)), and it only drew around 100 mA while operating. Of course, all it was doing was receiving serial data, storing it to an SD card, and printing data to an LCD, so I wouldn't be at all surprised if the TX board draws more than that, but I wouldn't think it should be much more, at least when the fan isn't running.

The total average consumption of the TX v2.50 board is around 60 to 70 mA, it obviously increase if you use a fan for the radiation shield

What I have in mind to power my station is a 10W panel/charge controller, and a 12V/7AH sealed lead-acid battery.

Depending on your latitude it may be more than enough, or not
My system is running for 3 years with a 10W solar panel and a 14Ah sealed lead-acid battery, and some times it is powering two TX units at the same time. Never was any problem, even in the winter.

Of course the two "prime movers" (Werk_ and _Bob) are located where they probably have more solar power than they know what to do with. But for those of us in higher latitudes, solar powering can be quite problematic. There is a thread on this forum where somebody was attempting to design a "reliable" solar supply, and (IMHO) the figures were quite frightening, but perhaps over-pessimistic.

Yes, here in Portugal, we have the luck of having lots of sunshine hours, even in the winter, and we really know what to do with it: By luck, we also have magnific beaches, nice girls and bars

I think that most AU regions have plenty of sun too.

I'm aware of the "study" from hvalentim, which have concluded the need of a 80W solar panel for a specific location in the UK. Quite exaggerated, I'm sure.