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February 25, 2007

LC III(a) My homework: making a torch

One of the ideas of taking the course was to make touches that first the children could use in the evenings and also to sell them as a source of employment for the boys. We had the casing obtained from a torch made at Timbaktu collective of which a couple of LEDs had stopped working. On opening the torch we realized that there was no current limiting circuit and the torch had been placed on the mercy of the characteristic of the LEDs as four LEDs were connected in series.

We had an alternate circuit Krishna had seen on the net and I had corrected could potentially be a constant current circuit which seemed quite preferable for longer lifetime as well as protection for the LEDs for any odd over-voltages.

I had to split the board into two pieces; one for the leds in the top and another for the circuit which was to be inside. We also wanted to change the switch to something that didn’t need to be pressed as long as light was needed. Ultimately, it turned out to be a bit of a squeeze, but we managed to put it together and get the kids excited all about it.

More than the kids though Krishna seemed very excited and carried the torch everywhere for the next few days :).

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