I found an old broken bicycle flashlight and I immediately took it apart to try and see if there was any obvious reason for why it wasn't working. From the looks of it the PCB was probably water damaged so I decided to upgrade the flashlight a bit with two 1W led's and make a super bright flashlight out of it.
Step 1: Taking It Apart
This fairly standard flashlight contains three standard 5mm led's that has a small controller board to make it blink in different patterns. Since I didn't need any of that blinking stuff but rather wanted to make a powerful light instead I just removed all that stuff leaving me with an empty shell.
The leds were still working on this flashlight so I saved them for future projects.
Step 2: Preparing the Leds
These cheap 1W leds are quite powerful and require some kind of heat sink so they don't overheat. I had a piece of some aluminium rods that I cut down to like 1 cm length to be able to fit inside the led housing.
To attach the leds to the heat sink one could probably use thermal glue or thermal sticker to attach the leds but I had none of that so I soldered it straight on the heat sink.
The heat sink was a bit too big for my soldering station to quickly heat up but a bit too small for an oven so I just used a couple of things I found on my desk at that moment to build me a small heating device. I used the aluminium holder for a tealight drilled a small hole for the heat from another tealight and then placed the heat sink on that with the led on with some solder paste in between.
This was a bit tricky since the led floated on the liquid tin and started moving around before I manage to cool it down. but after a while I got a hang of it and it turned out quite well :-)
Step 3: Placing the Components
It was a snug fit to get the wires through but that's probably a good thing to keep the leds in place. I also used some electrical tape to make sure that no shorts could occur.
For the switch I had to use another switch that I also had lying around (bought it earlier for another project) since the switch that came with the light was a momentary switch and so the light was digitally controlled through the controller board. I had to modify the switch a but by cutting off a small piece but after that it fit perfectly.
Step 4: Result
The flaslight turned out great and is WAY brighter now than before. The only issue I have is probably that the light, without any focus or reflector spreads almost 360 degrees round, making it impractical for long distance lightening. But It does light up a room quite well. I've used it for quite a while now and it doesn't seem to overheat or anything like that. But I would like to switch out the batteries from the standard AAA batteries that it uses now to like a Lithium battery instead.