Two laser pointers

[tom3000]

Button battery cells have an internal resistance that limits their current so the laser is not destroyed. A laser needs about 3V at about 40mA. Then the 4.5V worth of button battery cells have a total internal resistance of 37.5 ohms. Your 4.5V LM317 or 3 AA cells will burn the laser out.

dude, have you read what I said ?

if not then here it is again, THERE IS AN ADDITIONAL (current limiting) RESISTOR right behind the laser diode, there's no need for any other components (well at least for the laser pointers that I have)

 

[cannibal]

May I know where is the + and - in the laser so I can test without the switchs

I will be happy if you guys show me in the image that I attached

 

[audioguru]

I will be happy if you guys show me in the image that I attached

YOU took it apart, not us. So YOU should have marked which terminal polarity is which.

 

[cannibal]

I only removed the cover
I didn't cut anything !!

 

[audioguru]

I only removed the cover
I didn't cut anything !!

Then simply look at the polarity of the battery cells to see which wire of the laser is positive and which is negative. The on-off switch will be in series with one of them.

 

[Purple Rabbit]

3AAA method

Yep, i tried the 3AAA batt approach and it worked......until the laser burnt out! I would take audioguru's advice, unless you know the value of the resistor, the one on mine was blank and sealed into the plastic case so i had no way of finding its value.

 

[audioguru]

Yep, i tried the 3AAA batt approach and it worked......until the laser burnt out!

Hee, hee.
I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, I told you so, etc.

 

[tom3000]

Yep, i tried the 3AAA batt approach and it worked......until the laser burnt out! I would take audioguru's advice, unless you know the value of the resistor, the one on mine was blank and sealed into the plastic case so i had no way of finding its value.

mines are ~71 ohms surface mount

when one thinks about those laser diodes they actually do drop ~3V

(4.5 - 3) / 71 = ~21 mA which is just about right for a diode

 

[cannibal]

I found that the laser that I am using has internal resisitor

so I used my 5V power supply directly to it and it's working fine
and I tried to OFF,ON alot of time and everything seems ok