Each time I have make one of these I always think – this could be better. The first 2 versions which can be found here and here, worked out ok but I have discovered that batteries don’t like to be enclosed and that their fail rate goes up dramatically when they are. This is due to the fact the batteries need to breath and once encased in resin suffer a slow death. I can still charge up the original ones but the batteries only last for a couple hours.
So I was thinking the best way to fix this would be to remove the batteries altogether. I did toy with super caps but a quick search on the net show they wouldn't be suitable for the job. Caps release their energy quickly and this just won’t work on something like this.
I finally decided to go down the path of using a wireless charging module. These are really easy to use and work like a charm. I used one in version 2 to charge the batteries up.
The other really cool thing about this version is the LED light. It comes with a remote and has heaps of features which allows you to change the colour and display of the LED's.
The project itself is quite simple and the only real messing about is making the box that the cube sits on. But you could easily simplify this and just use a brought box of your choice.
You can also click "here" to watch the video
and here's how you make one...
Step 1: Bits and Tools
Things to gather:
1. LED Globe – eBay
2. Heat-sink – eBay
3. Wireless charging module – here
4. Small nut
5. Clear casting resin – I got mine from my local hardware store and it's called "diggers clear casting resin"
6. Female power adapter - Local electronics store. I didn't use this one but it would work fine - eBay
7. 3 way switch - eBay
8. Wood to make the base. I used some thin ply board and 10mm by 50mm lengths of hardwood.
9. 9v battery clip - eBay
1. Soldering Iron
2. Super glue
3. Screwdriver etc
4. Wire cutters
Step 2: Pulling Things Apart
1. Remove the fan from the heat-sink.
2. Un-screw the bottom of the light bulb. The red and black wires sticking out are from the circuit board and should have broken off from the bottom of the globe once you un-screwed it.
3. Use a screwdriver to pop open the top of the globe.
4. Un-screw the circuit board from the globe.
Step 3: Re-asssembling
1. First glue down the small circuit board that comes with the wireless charger, to the inside of the heat-sink.
2. Next de-solder the red and black wires from the LED circuit board.
3. Thread the red and black wires from the charger through the hole in the centre of the LED circuit board and solder into place.
4. Glue a nut in the centre of the heat-sink. This will act as a heat-sink itself and will prevent the LED circuit board moving too far inside the heat-sink. What’s really cool is the hole in the heat-sink where the fan went is a perfect fit for the LED’s. If you wanted to, you could have the LED circuit sitting right down into the heat-sink.
5. Glue the copper coil from the charger to the bottom of the heat-sink.
Note - Initially I was going to have the charging circuit board stuck to the bottom of the heat-sink. you can see in one of the photos a holed drilled into the middle of the heat-sink and the wires from the charger sticking through the screw holes. I decided not to go down this option as it looks a little untidy.
Step 4: Adding the Resin
I decided to make my own mold this time as it's very hard to find one with sharp 90 degree corners.
1. Make your mold. I used core flute which is the material that is used to make temporary signs. It can be purchased at most art shops or you can just use an old sign!)
2. Measure out how big you want the mold. mine is about 15mm larger than the heat-sink.
3. For the walls all you need to do is measure a long piece and lightly score 4 times the width you want the cube. Use hot glue to stick to a base and the wall together. Be liberal with the glue - it's better to go overboard then have leaks!
NOTE: Core flute has channels all the way through it. I would suggest using some blue tac or clay to block up the holes where the walls are joined to the base. I lost a lot of resin because it seeped up the channels.
4. pour a little resin on the bottom and position the heat-sink in the middle.
4. Pour the rest of the resin and leave for 12 hours. The best hint I can give you when using resin is don't go overboard with the catalyst. If you add too much the resin will heat up and crack, believe me - I know.
Step 5: Smoothing Out the Resin
1. If you used core flute as the mold you will notice the resin has lines running down it. You will need to get some 400 sandpaper and start sanding. You could use a rougher grit paper but you might put some deep lines into the resin.
2. Once you have all the sides smooth it's time to use a 600 grit sandpaper and get rid of the scratches. Once this has been done move onto a 1200 grit paper to create the final finish.
Note :I left the cube translucent as I wanted the LED light to be diffused. You can polish the resin even further so it is clear like water but the LED's won't be diffused.
Step 6: Making the Base
1. Cut 4 pieces of wood to make the sides of the box and glue together.
2. Next work out where to want to add the switch and female power adapter and cut some grooves into the box to accommodate them.
3. Next cut some thin ply board for the sides, base and top and glue to the box sides. You will need to do the usual measurements and sanding to get all of the dimensions right.
4. Drill some holes where the grooves are in the box and add the switch and adapter.
Step 7: Electronics
I have added a diagram which shows how I wired everything up. It's pretty straight forward so I won't drill down too much on what to do. Just remember to test out your AC adapter before you wire everything up to ensure the polarities are correct. I used 9v 1A adapter which I had to drop down the amperage with a resister. The most that the wireless charger can take is 600ma and I dropped it down to 500ma just to be safe.
Step 8: Painting
1. Use a stain and rub it onto the box. I only did 1 coat but it's up to you want stain to use.
2. Next I used a lacquer to give the box a shine and added about 3 coats. Don''t forget to lightly sand the first coat.
3. Once dry you need to drill a couple of holes into the lid. This is where the coil wires will go through. De-solder the coil from the yellow box it is joined to and thread through the holes in the lid. Re-solder and hot glue the yellow box to the side of the wooden box.
4. Before you super glue down the coil to the top of the lid, test with the cube and work out the best spot for it to go.
5. Lastly I added 4 pads on each corner of the lid so the cube would sit straight. I used a hot glue stick and just cut 4 small slices.
Step 9: Finished.
I don't really think that you have to use the charging coil if you didn't want to. You could use a couple of copper pads which would need to be flat on the bottom of the resin. When the resin is hard you could sand until the pads are relieved. Then it would be just a matter of adding a couple more pads onto the lid of the box and your done.
Also, you could just have a couple of wires coming straight out of the resin and join this up to the battery etc outside the resin. It would mean that you couldn't remove the resin cube but It wouldn't really matter. It would also make things a hell lot easier.
If you decide to make one of these, post an image of it on the comments. I'd love to see what everyone else could do with this.