So this is a two-part instructable, the first being the LED driver circuit, (don't worry, it's very simple) the second part being the physical lamp. This is an extremely flexible design, just about any LED can be used, and just about any, low power, power source, including USB. Also, I decided to use a seashell for the decoration, but again, very adaptable, you can use anything you want. Anyway, let's build it!
Step 1: Materials
First we should gather up the supplies needed.
* NPN transistor (I used 3904: http://www.taydaelectronics.com/2n3904-npn-general-propose-transistor.html)
* 39 Ohm resistor (x2) (http://www.taydaelectronics.com/resistors/1-4w-carbon-film-resistors/10-x-resistor-39-ohm-1-4w-5-carbon-film-pkg-of-10.html)
* 10k Ohm resistor (http://www.taydaelectronics.com/resistors/1-4w-carbon-film-resistors/10-x-resistor-10k-ohm-1-4w-5-carbon-film-pkg-of-10.html)
* 1n4007 diodes, or similar (x2) (http://www.taydaelectronics.com/1n4007-1a-1000v-rectifier-diode.html)
* LED(s) I used two of these in parallel (http://www.dx.com/p/0-5w-3000-3150k-40-45lm-led-warm-white-light-bulbs-20-piece-pack-146614#.VAjUj2SwLKs) but you can use something like these (http://www.taydaelectronics.com/leds/round-leds.html) 3mm or 5mm
* prototype board (optional, but convenient) (http://www.taydaelectronics.com/hardware/prototyping-boards/small-stripboard-94x53mm-copper.html) I actually used plain perf board
* trimmer potentiometer (optional, I pulled mine out of an old DVD player)
* DC jack or USB port (I used a DC jack) (http://www.taydaelectronics.com/hardware/dc-power/dc-power-jack-2-1mm-barrel-type-pcb-mount.html) (http://www.taydaelectronics.com/connectors-sockets/usb-connectors/usb-type-a-female-connector.html)
* 7805 voltage regulator (not needed if USB is power source) (http://www.taydaelectronics.com/ic-integrated-circuits/voltage-regulators/lm7805-l7805-7805-voltage-regulator-ic-5v-1-5a.html)
* USB cable or power supply
* seashell (or whatever you want to use)
* wooden base ( or whatever you want to use)
* oil/polyurethane for the base (optional)
* soldering iron
* wood working tools
* hot glue gun
* pliers/wire strippers
Step 2: The Driver Circuit
Now, we could obviously use just a resistor, but where's the fun in that? Alternatively, we could use a pre-built driver, but I have yet to find on that is as low power as we need, and again, where's the fun in that? Instead we will make one from scratch, I came across this excellent instructable a while ago (https://www.instructables.com/id/Simple-Led-driverConstant-current-source-20-mA/) and it is perfect for the LED(s) we will use. The first schematic is the one from the other instructable and the basis for mine. The second one is the circuit I actually used. 1-yes this is the symbol for a MOSFET, but this is where the voltage regulator goes. 2-this pin is indeed attached to nothing. Simply arrange the components on a perf board, and solder. That sounds a lot easier than it is, don't worry if you mess up a few times. Also, the transistor is very sensitive to heat, so make sure to solder it quickly, don't leave the iron on it for more than one or two seconds. If you decide to use SMT LEDs like I did, solder them to wires that can go into the perf board, actually, do this with any LEDs. Then test it out, if it doesn't turn on at all, check the connections, make sure you followed the schematic correctly. If it lights up a little, like mine did, try replacing the transistor. If all the components are working and the connections are correct and it still doesn't work, well...I guess just rebuilt the circuit on a different piece of perf board and with different components. The next step is to build the lamp.
Step 3: The Lamp Base
Next we take a board, of nice wood of course, and draw the shape needed for the seashell, or whatever you want to use for the decorative lamp shade. It could be a square, a circle, an oval, but I chose to make it an oval-with-flat-sides-thing shape. We now have to cut it out using a band saw, jig saw, coping saw, or chainsaw (not recommended). Once it is cut out we sand it down to make it smooth and pretty :). Now we need to make a place for the LED driver to go. To do this we simply drill out, or chisel, the underside of the board. Don't worry about small holes poking through, they will be covered by the seashell. One large hole needs to be drilled through the board, this is where the LED will go through to the top. Make sure to create an area on one side where the power cord can plug in (more on that in the next step). Now we're ready to finish it, for the board I used common 3-in-1 household oil and just rubbed it in. For the shell I sprayed it with polyurethane to give it a shine.
Step 4: Put the Driver Circuit Inside the Board
This is a very important step, we need to position the driver so that we can plug in the power source through a hole in the wood. As thou can see, I cut a notch into the side of the wood, this is where the female side of the jack goes. This notch needs to be deep enough that the wood separating the male and female side is thin. This is so that the plug actually makes contact inside the female jack. Once we have it positioned correctly, we can hot glue it in, feel free to use a bunch of glue, as that is the only thing holding the circuit in. we then take the LEDs and put them through the hole we made, and glue them to the top of the board. We're almost done!
Step 5: Add the Seashell and Other Finishing Touches
Take the hot glue gun and run a line of glue around the rim of the shell. Then simply press the shell onto the board. I decided to add some rubber feet to the bottom, so I glued four small rubber washers onto the bottom of the board. Add as many additional decorations as you want, tell me in the comment section what you did different or in addition to my design.
Step 6: Done!
Now we are done! Plug it in and enjoy the warm, peaceful light it gives off. It makes an excellent night light.