Awb of Orsome

Easter 2011, I decided to challenge myself to finish a project from conception to completion in a day. Kind of like a Hack-a-day, except for one day. This page documents the result, the 'Awb of Orsome'1.

What is the 'Awb'? The 'awb' is a decorative light thing. It's a chunk of timber with a translucent globe on top that displays a randomish set of coloured blobs. It's a modern junkyard equivalent to a lava lamp.

Everything used in this project is recycled, to some extent by necessity, the time constraint meant that I couldn't really go out shopping for items.

The Bill of Materials

The project started with a slice of a chinese elm branch that we'd have cropped from our backyard because it was growing in the wrong place. I quite like the elm, especially its bark, so I thought it'd make a nice base for something. The colour-cycling LEDs came from a bunch of tacky solar-powered garden lamps that never really looked very good in the garden. The mounting hardware for the LEDs came from the inside of a "Kinder Surprise" egg that I found in one of the kids bedrooms. The globe I had laying around from an aborted steampunk project some time prior.

The power supply is an old USB charger for a defunct telephone, they make quite decent low current 5V supplies. The resistors and veroboard were in my junk-box and the tubing I cut from a roll I had acquired for some other project. The wire I recovered from a length of multi-pair telephone cable.

What isn't shown, because I forgot to photograph it, is a small brass plate, rubber grommet and miniature toggle switch to cover the hole where the resistors are inserted and the power cable is fed.

Assembly

There is nothing technically difficult about this project. The challenge was to actually complete a project, and in a day, not do anything particularly innovative or inventive.

• 1. I chose to use one resistor per LED because I didn't know much about the technical specifications of them. Waving one about in front of my face while it was lit made it quickly obvious they were pulse width modulated, so I  thought isolating them would be best. The resistor value I found by trial and error. With a 5V supply, 100 ohms seems to work pretty well.

  2. Much of the time was spent in working the wood and waiting for the estapol to dry. I simply drilled two holes, one from the side and one from the top, that met each other. I then used a handfile to open the top hole up so the globe would sit snugly inside it.

  3. I soldered pairs of wire onto each LED and insulated the joins with heat-shrink cable. I punched some holes in the 'egg' and fed the wires through.

  4. Resistors onto veroboard, they all share a leg and branch into seperate connections on the other side.

  5. Feed the LED wires through the tubing and solder them onto the veroboard.

  6. Feed the power cable through the grommet and through the brass plate, through the side hole. One leg goes up out of the top hole of the mount, solder one leg onto the vero board, the other leg goes onto the toggle switch. Conforming to now old practice I tired a loose knot in the power cable on the inner side of the grommet to act as strain relief.

  7. Finally run a wire between the other leg of the switch to a join of the second LED legs. Heatshrink to insulate.

  8. Insert the tube into the top hole, fold excess LED cable into it and sit the 'egg' onto the top of the tube.

  9. Grommet into brass plate, brass plate is screwed into the side of the mount.

  10. Place the globe over the top of the LED array.

  11. Plug in the adaptor and turn on the power switch.

  12. 'Awwww'.

I was going to get funky with trying to refract the light around inside of the globe by using crumpled clear cellophane or even marbles, but in practice the LEDs actually emit light in a circular pattern and I think they look ok as they are, so I haven't yet bothered. The LEDs each cycle around at their own pace. They start out in sync, but over time differences between each causes them to end up in different parts of their cycle and you end up with all sorts of interesting patterns of colours projected onto the inside of the globe.

Notes:

• 1. Apologies for the name, it's not my own, it's my son's suggestion.