- A spare 12Wh Li-Ion battery left over from my Kodi car entertainment project.
- Two broken 1W 12V LED "bulbs", meant as Halogen bulb replacements.
- Some magnets from old computer harddisks.
- An Adafruit micro Li-Po/Li-Ion USB charger.
A Pololu 5V Step-Up Voltage Regulator U1V11F5. A BC557C PNP transistor. 10 kOhm, 22 kOhm, 47 kOhm resitors. 22-47 uF 16V capacitor.
- 10 Ohm, 4.7 Ohm resistors.
- 100 Ohm potentiometer.
UPDATE: You can simply connect the battery to the lamp input! No step-up regulator needed! This makes the runtime even longer! The lamp will grow dimmer when the Li-Ion voltage drops and I've not seen it go below ~3.2V.
I've added a 100 Ohm potentiometer in series to the combined 3.2 Ohm resistor so you can adjust the brightness really easy.
Voila, a mobile Li-Ion lamp. I think I'll build a nice wooden enclosure for it...