Sanjiv Dutta saved some money when he decided to make this LED Based Handycam Light instead of going to the store and buying one. It looks very bright and based on the pictures on his site (scroll to the bottom) it seems to work very well!

“I have come with a naive solution, but a working one. I put resistors to drop the supply voltage when needed, by means of a 3 position switch as described in the Ckt. below.

Lets see the current & voltage delivered to the LEDs that way:-
It was found that , when voltage across LED = 3 v, current consumption = 20 mA approx.
And for 3.1.v, it becomes about 22 mA.
For 20 LEDs, that is = 440 mA
Hence, if Supply voltage is 3.6 v, voltage drop needed across the resistor = 0.5 v.
Again, when Supply voltage drops to 3.3 v, voltage drop needed across the resistor = 0.2 v.
We do not need any resistors when Supply voltage further drops to 3.1 v or 3 v.
Thus we found out the required resistor values.”

(more…)

Here is a better look at the cool LED fabric that was shown last week.

“This video shows the full extent of how far the technology has gone, with different colors, how the fabric reacts to touch (which is surprisingly like a normal fabric) and how LumaLive can be made useful on other things like sofas or in other places around the house. For example, a Lumalive clock on your Sofa would be very useful. After watching the video, you’ll know why this is technology is called LumaLive. Whats next - TV in our clothes?”

Via: Gadgets.qj.net