On my instructable i will teach you on how to make your own rechargable flash light using some junk laying around.
it also has a blinking led that you can use as a signal light for your bike or anything else...

## Step 1: Step 1: Prepare Your Materials.

The materials that you need are:

1. super bright white led. 4pcs 5mm
2. super bright blue led blink 1pc 1cm.
3. resistors (the resistors will depend on the computation you have come up.)
4. junk plastics.
5. glue.
6. li-ion battery. or any battery that has high capacity.
7. crown plug female plug. (i got this from my broken MP4 player.it will depend on the male plug of the charger that  you will use.)
8. any tools that you might need.

## Step 2: Step 2: Compute for the Resistor Value.

here is the computation you have to use to get the right value for the resistor that you need.

R = (VS - VL) / I

R= resistor value
Vs=voltage supply
Vl= voltage to be supplied
I = ampere of the part you must supply.

## Step 3: Step 3: Putting the Parts Together.

here is the diagram of the parts.

I DESIGNED THIS BASED ON THE THINGS THAT I HAVE FOUND LAYING AROUND.

about the resistor led part. you can use only one resistor if you have 4 same leds on a parallel connection. if you will use different kinds  of led, each led must have their own resistor.

## Step 4: Step 4: Making the Case.

the casing of my flashlight come from junk plastics,
so i formed it on my own method that is shown here.

## Step 5: Step 5: Putting the Parts Inside.

after completing the casing, you can now put the parts inside the casing and solder them together. you can glue some of them to make sure that they will not be removed easily on the casing. use insulating materials to insulate 'near to short circuit' parts.

## Step 6: Step 6: Enclosing the Casing and Now You Are Finished.

i designed the case to be mounted by screws so if there is something wrong i can easily replace the damaged part of my designed circuit.

you can watch the video on how it works on my youtube account.

5 volt from usb + leaving on the charger too long = <a href="http://www.youtube.com/watch?v=lCFUGDcSuLw&amp;feature=related" rel="nofollow"><strong>Vent With Flame</strong></a><br /> <br /> Drop the voltage down to 4.2 and you can more safely charge the battery(though it does take a LITTLE longer).<br /> <br /> Given a PC usb port(limited to 500mAh), and a charging voltage of 4.2, ...<br /> a <a href="http://parts.digikey.sg/1/1/7057-res-1-8-ohm-1w-5-metal-oxide-rsf100jb-1r8.html" rel="nofollow">1.8 ohm resistor</a> should work wonders..., You should be able to safely charge for a number of hours without undue risk.<br /> <br /> Still, don't leave charging unattended...but a few hours SHOULD be ok.<br /> first couple of charges, monitor batter temperature.<br /> <br /> <br /> <br /> Hmm, Oh I see, maybe.<br /> <br /> If that blinking Blue LED can draw off the extra .8 volts..then you'd be golden.<br /> Worth hooking up the multimeter, and seeing what voltage the battery sees while charging, with the led blinking.<br />
this one didnt use any usb chargers, the resistor will depend on the charger that you will use that's why i presented the computations on this instructable, about the charging time, i didnt include that here because it will depend on your work on what charging time it will require.<br /> <br /> get it?<br /> <br /> my tip is just dont mess up with your work so you and your work can be safe,<br />
Mia Culpa.<br /> <br /> I failed to switch to the second image of step 6.<br /> The first image has the blurry plug labled as &quot;female plug from junk mp4 player&quot; and the blur sorta kinda looked like a mini-usb port, common to so many small electronics devices like cell phones and media players.<br /> <br /> After reading your comment, re-reading the 'ible, and switching over to the <strong>crystal clear</strong> second image for step 6... I now understand :-) tyhanks for not jumping down my throat :-)<br /> <br /> Keep up the great instructables.
about the female plug from junk mp4 that i used, its not a usb female port, it looks like a crown plug but a smaller one, and i don't know if it is a crown plug because i just recycled it,<br /> <br /> thanks by the way!!!<br />