Making LED devices portable can be a little bulky due to the batteries. The Joule Thief solves that, by boosting a single AA battery's voltage to a high enough level to light a LED.
This ible will entail how to solder a joule thief together from www.thejoulethief.com. They cost $7 each.
The kit from thejoulethief is interesting in the fact that it deviates from the standard bulky joule thief design to a small and compact pcb layout with a few extra components for efficiency.
Step 1: Open Source
Attached are the Eagle schematic and board files.
Step 2: Gather Parts
Make sure you have all of the parts. Here is the listing:
Qty 2. Transistor
Qty 2. 1k resistor
LED (your choice of color)
Qty 2. wire pieces
Step 3: Inductor
I first chose to put in the inductor. The inductor looks like a fat resistor. There is a spot on the PCB labeled "L1" where the inductor should go.
Insert the inductor, bend the leads so that it says put, and solder it in.
Step 4: Resistors
Time for the resistors.
R1 is the 2.2k resistor (red red red).
R2 and R3 are the 1k resistors (brown black red)
Note that you should mount the resistors vertically to save space.
Insert, bend leads, and solder!
Step 5: Capacitor
Grab the capacitor, insert in the spot labeled C1, bend and solder.
Step 6: Transistors
The next step is kind of tricky. The transistor leads are normally in line, however to insert them in the PCB you will need to bend the leads into a triangle shape (see picture).
After bending the leads, carefully push down the transistor into the pcb until it seats nicely. Solder.
Step 7: LED
The fun part! Put the LED in, make sure you note the orientation. The flat spot on the LED goes towards the flat spot on the silkscreen.
Step 8: Wire
Here is the final step. Strip the wire ends, and solder it into the pads on the PCB.
Next it is time to test it out!
Step 9: Testing
The silkscreen marks which wire is positive and negative. Put the proper leads to any AA battery, dead or new, and see the LED light!
This is a great way to get compact LED lighting, using a minuscule circuit and one AA battery. The circuit operates off of "dead" AA batteries, making it a great way to reuse your old AAs.
Pick up a kit at www.thejoulethief.com and have fun!