solar powered pocket torch

solar powered pocket torch Pocket torches are handy things, but they have one great drawback: at the most inconvenient moments their batteries go flat. It is therefore logical to make use of the everpresent energy source, the sun. This design incorporates a Siemens power-LED which can handle a maximum continuous current of 800 mA, and because of its high efficiency it gives as much light as a 5 Watt lightbulb. An or- dinary torch bulb can be used as shown in figure lb, however in some cases, oscillation may occur due to the self-induction of the filament. This can be avoided by simply adding a 100 pF capacitor, CThx.e LED is driven by two S.I.P. MOS-FET"s. Their extremely high slope (approximately: 2000 mA/V!) enables them to convert the initial 0.4 V of the solar cells into the 800 mA drive current required for the LED. D1 -= LD 241, LD 242 T1 = ZUB 10 12 -= BUZ 10 see text 2p V/800 rnVg 14 The circuit is balanced by means of Pl. This poten- tiometer should be set in such a way t...