After this week's meeting, a few of us got to discussing a find I made at Dollar Tree, namely a small solar-recharging 'desk lamp' which contains: - 3 white leds - 200mah Ni-Cd AAA cell - A small solar panel - A tiny on-off slide switch - A small circuit board with an YX805 LED and an inductor and the 3 parallel-wired LEDs The YX805 is the same as a 5252 LED Driver and has a data sheet here: This IC uses the inductor to boost the 1.5 volt battery to sufficent voltage to light the leds, and the value of the inductor controls the current available to the LEDS. The chip also has a cutoff value of incoming solar panel voltage to switch the LEDs on when the ambient light drops. The cutoff has hysterisis sufficent to keep the LEDs from blinking, and it also provides a battery-protecting cut off that prevents the battery from being too deeply discharged. For a buck, it's a nice little night-light, there's quite a few parts that could be useful in other projects. other uses, such as a power failure light that could be useful in dark hallways or basements. =^_^= Tigerwolf George, K9TGR |
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