At EMFCamp in 2012, I picked up a round PCB with a bunch of white LEDs with series resistors, courtesy of an generous attendee who had skipdived a bunch and was handing them out as fuel for hackery.
I wanted a tent light for the Southwold trip, and thought I'd make one from one of these PCBs. I guessed that they were built to run off 5V, and a USB power pack seemed like the right kind of power source..
I used an ATTiny45 to do PWM brightness control, via a VNP5N07 ONMIFET salvaged from an old PCB, and a microswitch. And a little electrolytic capacitor on the power rail, without which the ATtiny would reset every time the LED turned on.
All that fits on a bit of matrix board no bigger than the LED board:
A cable tie and some self-amalgamating tape makes a tidy bundle. Power is via an old USB lead.
And it all goes inside a pingpong ball for a bit of diffusion.
Here's the Arduino source, such as it it. See the comments in there for wiring instructions.
It has five brightness levels, in powers of 2, from 200 mW to 3W. And nearly every part of it is salvaged.Home | Artefacts| Robots