Opened flashlight - Parts can be used?

[jonasa0601]

Hey, my dad sells lots of different things, and he got me this defective flashlight today. I took it apart to see what was inside. The flashlight had two lights two different places, so it had 2 buttons. One of the lights was 5 LEDs and the other had 21 LEDs. (Good quality i think!). The small circuitboard the 5 LEDs is connected to, also have a small red diode, and an input for the battery(So it can recharge). The small red light lights when the battery is fully charged, and maybe it could be used in a laser? Please help me, it's my first real "project" if this works
How can i find out the LEDs required voltages etc? The battery is "Li-Ion 3.7V 1000mAh" so the LEDs only need that?
Here's some pictures:
This strange black thing was inside, it is very light, and on the back it has some white tape?
http://img16.imageshack.us/img16/5669/billede0337.jpg
Link because image didn't resize..

Here's the circuitboard with 5 LEDs, the black thing is the input for charge, and the small red diode is on the back/side.

 

[Deleted member 8178]

Voltage and current for your white LEDs: 3.3V (ish), 20mA.

 

[jonasa0601]

Okay, can i just put a 3.7V battery on?

Can you answer other questions?

 

[Deleted member 8178]

You must use a resistor to limit the current. Look up on google for a LED calculator. You can use the red light if you want: 2V, 10-20mA.

 

[jonasa0601]

If i wanna test what voltage the diodes are at, should i get one of the things that you can slowly turn up the voltage? How can i on future items find out the needed voltage, without frying anything. ?

 

[laser83]

If i wanna test what voltage the diodes are at, should i get one of the things that you can slowly turn up the voltage? How can i on future items find out the needed voltage, without frying anything. ?

You'll need an adjustable power supply and not the PC kind. There are test kits that will help. http://stonetek.org/shop/index.php?main_page=product_info&cPath=71&products_id=223 of course it's not that simple, that's the fun part!

 

[jonasa0601]

That's what i thourd. :/
Where can i buy adjustable powersupply? There's no electronic store in my city.. Even though it has 60.000 people living there.

 

[jonasa0601]

Do you say i have to buy an adjustable power supply? I can only find some at >100$

The thing your linking too, is like some LEDs? I mean if you take the amount of Leds in a "chain" that overall takes the same amount power current etc. as the selected LD?

 

[jonasa0601]

Can someone say what price range an adjustable power supply cost? I've searched, but only rather expensive posts have been found. Anyone knows what the black thing i posted a pic of is? There was also a strong magnet inside the flashlight.?