I want to have an extremely long-lived (at least one year) blinking LED with a single battery, like one 9V. Think like the battery indicator light in a smoke detector.
The LED doesn't matter to me. Preferably I could use a cheap 5mm one. I have already tried this with a standard 555 timer and LMC555 CMOS timer, the latter lasting longer than the former but both only into a range of several weeks. I also used a modified duty cycle that was well less than 50%. I believe the issue is that any of the 555 timers will draw some power that will eventually drain a 9V well before a year.
A Leona Esaki circuit seems finicky; I can't even get it to work with my current set of transistors.
Best Answer
Do the math.
A LiSOCl2 AA size battery has a capacity of 2400 mAH. A 1mA LED current is equivalent to 8760mAH per year, so your duty-cycle must be lower than 28%. Take 10% to be on the safe side and leave some current for the timing circuit. That means your LED draws an average of 100uA. A simple micro-controller can be made to draw much less (< 1uA).
uint128_t quotes 500mAH cacacity for a 9V block. That's around 1/5 of the LiSOCL2 I would choose, so for the same 1mA the duty-cycle must be ~ 2%. Or take a low-current LED. Test it: is it bright enough for you at 0.1mA?
Did you measure the average current drawn by your C555 circuit? According to the datasheet ~ 0.5mA must be attainable.