In this instructable, I will show how to mod this classic model of flashlight into a new LEDs flashlight. Basically replacing the old light bulb with a bunch of LEDs.
Step 1: Material
This is a pretty cheap instructable (provided you have the flashlight already!).
You'll just need:
-A bit of a styrofoam tray (or anything that could work as a frame for the LEDs but also that can be pierced, like wood, cardboard, plastics...);
-Some thin wire
And as tools:
Step 2: Assembling the LEDs
You just need to cut a circle of the white foam and drive the LEDs into it. There's one in the middle, six in the inner circle and 11 in the outer circle.
Make it in a way that pins with the same polarity are all in the same circle as shown on the circuit scheme. (Notice that in the circuit scheme there are more LEDs than I finally put).
Step 3: Wiring
I'm not changing anything in the flashlight except the lightbulb so the voltage provided remains the same, that is 3 volts (two batteries of 1,5V each). Each LED needs a bit more than that*, so we'll just need to connect them altogether in a shunt configuration (i.e. all positive pins together and all negative pins together). We won'to need any current limiting resistor as the intensity will be less than the maximum, because of the low voltage applied.
The simpler way to do it is as you can see in the pictures. Arrange them in circles, and then connect the circles with the same polarity. Then connect the circles to the battery terminals.
*The voltage will be less than required, and so it will be the light output. In case you want more voltage you'll need to hack the batteries system too. For example fitting 3 smaller batteries of 1,5V each. In that case you would need a current limiting resistor, but that's out of the scope of this instructable).
Step 4: Close and Enjoy
Now just close the lid in which you fitted the LEDs and be ready for the light!!
If you decide to do it, please try to do it cleaner than mine!! Consider mine as a first attempt to be improved.