A couple of months back (April if I recall) I was bored and looking for a nice project to kill some time in a rainy saturday. I decided to build a nice night light for my bedroom. I had a set of restrictions put in place so that I would be pleased with the final result, these were:

  • Must run on AAs
  • Adjustable intensity
  • Small and cute
  • Should be built entirely with parts that I had on hand
In use

The first challenge was to find a nice enclosure, since this was going to be used as decoration it couldn’t just be a bare protoboard with some LEDs or a boring project box. While looking through the pile of stuff (most people would call trash) I had stored in various places around the house, I found a couple of cubic flower pots made in various materials. I thought the ceramic one would fit my bedroom quite well, so that part was done.

Sanding the lens

The next thing would be to find a diffuser to cover the LEDs and and give a more uniform light. My first idea was to use acrylic or something like that, but sadly I didn’t have any on hand so I had to improvise. Again I went looking through my stuff and found an empty Ferrero Rocher enclosure (I knew I would use it some day), all I had to do was sand and cut it so it would fit the flower pot.

The finalized board

The last and most boring part was to solder all the LEDs, they are in a series parallel arrangement, with 9 parallel groups of 2 in series so that I could use a 9V supply. For driving them I decided to build a simple constant current sink with the two NPN transistors in a feedback configuration and designed it in such a way that it would be adjustable up to 100mA.

If you want to see more pictures of the whole process they are all available in this album: