Do not underestimate the effort of desoldering and soldering, though. It took me about a day altogether to finish the project.
Step 1: What you need
• 1 torch with 52 white LEDs, bought from eBay for 12 Euros, shipping included. I tried to get one with as much unused space inside as possible, and I was lucky. Maybe you can get a cheap one at your local electronics store and have it disassembled before buying.
• Given a 52 LED setting, I chose the following combination (all LEDs are of 5 mm diameter):
- 10 white LEDs (already included)
- 8 red LEDs
- 8 green LEDs
- 8 blue LEDs
- 9 infrared LEDs
- 9 ultraviolet LEDs
• With the chosen LEDs, I calculated the resistors needed (see next step) and bought:
- 4 resistors 1 Ohm, 0.5 Watts
- 1 resistor 12 Ohm, 0.5 Watts
- 1 resistor 5.6 Ohm, 0.5 Watts
- 9 resistors 27 Ohm, 0.5 Watts
• A rotary switch with 12 positions. You may get another one with less positions or use a totally different switch altogether.
• Isolated wire
• A small piece of circuit board for the 9 27 Ohm resistors
For tools I used:
• A 6.5 mm steel drill
• A dremel
• A soldering iron and some solder
• A glue gun