Lithium Torch

This mini pocket torch combines the advantages of Lithium button cells with a super-bright white LED. The lithium cells are small, have a long shelf life and have very little self-discharge. The LED has very high efficiency, an extremely long life expectancy and a modest current consumption (20 mA). In combination this results in an exceptionally long-life pocket torch.It is unfortunate that a Lithium cell has a voltage of only 3 V, while a super-LED has a forward voltage of 3.5 V. One cell will not suffice and we therefore will have to connect two in series.

Resistors:
P1 = 2kΩ5 preset
Capacitors:
C1 = 47nF
C2 = 22nF
Semiconductors:
D1 = super HR LED, white
IC1 = BTS629
(Conrad Electronics # 1759 86)
Miscellaneous:
S1 = pushbutton (e.g., Farnell # MCDTS-5M)
BT1 = 2 off CR2025 or CR2032
Case: KM type Box UM14 (Nedis)