Welcome to the Tuesday Teardown series, about looking inside the technology around us.
The other day, Ard Jonker pointed me to this item available at the Dutch Lidl stores for €12.95:
A solar LED light you put in the floor outside, which automatically lights up when it gets dark.
It’s about 14 cm in diameter, and 6 cm deep – let’s have a look inside:
A solar cell, with two white LEDs, held in place by two screws yearning to be removed:
The red leads connect to an on/off switch which can be accessed from outside. The batteries are 800 mAh, according to the specs, and look like standard replaceable AAA cells. The PCB has a chip on the other side:
Hey – not bad, two
NiCad NiMH’s and a little chip to drive the LEDs. This could easily accommodate a JNµ!
The DIP-8 chip in there seems to have logic for turning the LEDs on only when it’s dark (weak solar cell voltage, I assume). It does a bit more though, as this scope trace of one of the LED shows:
Probably some sort of charge-pumping, to drive the LEDs beyond the 2.5V supplied by the batteries. The power consumption is about 9.5 mA, so these lights should last through the night if there is enough sunlight during the day to fully recharge the batteries.
Neat. This could make an excellent power source plus enclosure for a JeeNode Micro, but note that the big metal ring is essential – it presses the glass and rubber seal tight against the rest of the enclosure “cups”.