The one-year flashlight

Russell Gurrin describes his design for a night light/flashlight that runs continuously for one year on three AA rechargeable batteries.

Russell Gurrin

Over the last 20 years or so, LEDs have become much more efficient at producing light, so much so that they’re now one of the most efficient light sources known. Back then, a “superbright” LED had a peak brightness of around 200mcd to 600mcd. With modern superbright LEDs, the peak brightness has increased to more than 20,000mcd, two orders of magnitude brighter, using the same amount of power. That got me thinking: instead of using the same amount of power to produce dazzlinglybright light, could these modern superbright LEDs produce a moderate amount of light with a hugely reduced power consumption? A bit of experimentation provided the answer: Yes, but not by using the usual single-resistor circuit to reduce the current flowing into the LED. I tried increasing the resistance…

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Renew (Digital) - 1 Issue, 166 / Jan-Mar 2024

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