[sdiy] thanks for replies - Blue LED

[Paul Perry]

I think an ICL7660 or one of the many similar 'improved'
voltage inverter/doublers should work. Looking at the data sheet,
they run fine on very low voltages... pretty cheap too.

There are also a vast number of (more expensive, and usually surface mount)
chips specifically designed for around 2.5 to 3v, for mobile phones.
Maybe one could scavange one from a discaded cell phone??

paul perry melbourne australia