There is a small device, I think is is used as a voltage reference in some way.
I believe it was referred to as 3812 or something. There is a very wide range of these devices rated at small voltages such as 2.2v, 2.4v, 2.6v.... from about 1.0 to nearly 4.0v.

Does this ring a bell for anyone!??!!

 

The device you are looking for is the one commonly used in solar-engines used in BEAM robots.

hgmjr

 

No wonder I couldn't find them, I was major lexdixit.
1381... That's them!

Thanks