Low current circuits - do they exist?

[SemiMan]

How long are you planning to have this thing in existence?

You can pick up 1W solar panels with over-voltage protection (for a lead-acid) for about $15 or so. I put a diode in series in mine as I don't like to have too high of a float charge voltage on the battery. Hook that up to a small, say Lead-Acid gel cell. Yes I know they have poor cold weather performance, but realistically, if you are keeping it charged, how much power do you need. That battery could be used to power a reasonable sized light and it is likely to last you years.

 

[yellow]

I cant believe You dont find "cheap" ready made low current drivers for 5 mm led (which usually run on 20 mA, so there must be numerous of these drivers)

f.e. such one: http://www.led-shop24.de/leds-3mm/micro-konstantstromquelle-20ma.htm
this is buck, but there are also 1-cell for sure
(sorry, its in German, have no better in mind atm, but there should be some available locally at Yours)
((and cheaper ones))

 

[JWP_EE]

I used this device to build a LED light a couple of years ago. It is very efficient. They also have some other parts that may better fit your needs. If you like building things it may be worth a look.

http://www.zetex.com/3.0/product_portfolio.asp?pno=ZXSC310&h=36