>
> Trying to run a PIC 16F84 with 2V i came to tihnk if there is any
> possibilities to make a LED to run with only one NiCd that has the output
> valtage of about 1.2 V. Led needs about 1.6 V.
> The system should not have any fancy IC's and it should fit in the size of
> half of an AAA-cell.
>
> Virtual beer for the best idea !

Don't know if this mail message will work...
However, I've done this, it's not too hard.
What I did.
Take small pot-core, break/sand to get a toroid of 3mm*1mm*1mm
Wrap with fine wire, to get a reasonable inductance (I picked
200Khz, and 60ma max current).
Then you need a way of switching this coil, at 200Khz or so.
I picked a multivibrator, as it was simplest, and diddn't require
much thinking to get working.
One end of one collector resistor was connected directly (IIRC) to
the base of the switching transistor.
The LED became it's own diode.
IIRC, efficiancy was around 85%.

I posted on this on misc.sirvivalism, dejanews should pick it up.
Final size was around 3mm long, and the diameter of an AAA cell, it
went in space made by extra compression of the spring, in a single
AAA cell light.
Transistors were surface mount, and the other components were mounted
round them, using fine enameled wire, which fluxes when soldered to.
Need a magnifying glass :)