external powering of laser pointer

On: Tue, Jan 07, 03 07:25:02 PM

peter wrote:

i have a small bullet style laser pointer that runs of the usual watch type battaries and i need to be able to power it from two rechargable AAA size battaries... any guidence on the best way to get this going would be greatly received....and if it could be powered from say a small 9 volt wall wart then im made right...


Jean Dufrasne - Wed, Jan 08, 03 10:11:58 AM

Hello Peter, No problem to power your laser pointer with 2 batteries but don't forget, you can destroy instantly your diode if you give to much volt. In your case, never go higher than 3 volts. I destroy my diode one month ago using an AC/DC power supply. When 3 volts selected, it's supply 4.5 volts, my diode burns (now it's mode op. is multimode) in less than then minute. Very frustating at 2:00 AM ! So, be carefull ! See you. Jean

peter - Wed, Jan 08, 03 02:37:09 PM

thanks for the tip jean....i have tried using two rechargable AAA size but it doesnt work...but i havent burnt the diode out either cos i checked with the required battaries so im not sure whats happening....the AAA type are rated at 1.2 volts 250 mAH...any further input here would be greatly appreciated...thanks

John K - Thu, Jan 09, 03 04:55:48 AM

I'm figuring you’re using nicad rechargeable batteries so you would be getting 2.4 volts. That might not be enough voltage to work. The other thing is that you might have the batteries to the wrong polarity. I am currently using 3 "c" alkaline batteries that givies me about 4.5 volts with an infinator 200 brand cheepo laser pointer. 4.5 volts may be too high for some laser pointers, but two alkaline c cells should be alright.

peter - Thu, Jan 09, 03 01:30:44 PM

thanks for the feedback john...i called into an electronics shop today and they told me that the required battaries run at 1.2 volts so 3 in series amounts to 3.6...ultimatly i would love to just have it running from an adaptor so its working at its peak capacity continuously....by the way i would just like to point out that im not actually involved in holography...well i think im not...my interest was born out of the visuals in clubs so im experimenting with lenses prisms crystals and automation of various elements to create the most dynamic effects...just flashing the laser at a polygon crystal in a dark room is so engaging...i just cant leave the stuff alone....sorry to go on....am i on the right forum for what im doing....this is the first time i have used a forum....thanks for your support..

Tom B. - Sun, Jan 12, 03 04:15:39 AM

The pointers of this type that I've seen just use a single resistor to limit the current and so they are very sensitive to the battery voltage. If you want to run from a higher voltage, you will need an extra resistor. I've probably already lost you, but first you want to measure the current the pointer draws at 3.6V, then if say the current is 0.040 Amps and your wall wart supplies 9V, the resistor you need to absorb the difference is (9V - 3.6V)/0.040 = 130 Ohms. But it doesn't have to be too precise - battery voltages are not precise either. You will need to buy a borrow a multimeter and find resistors somewhere - maybe Radio Shack?.

Jack Figgis - Tue, Jan 14, 03 08:30:45 PM

If using a mains powered supply make sure it's current limited. If it's not and you raise the voltage too high you'll destroy the diode, it may still work a bit but it will either be really dim or have a series of dark bars aligned with the long axis of the beam. Also turn the power supply on and off with the diode disconnected. Any spike and you will destroy the diode. Jacko

Brandon L - Thu, Jan 16, 03 08:48:15 PM
Hello I am wondering i have a 5mw flat laser pointer tht i got from radio shack it runs off a 3 volt cr2025 battery i am wanting to know how to use an AAA batteries to power it THE HELP WOULD BE EPRICIATED

peter - Tue, Jan 21, 03 03:17:32 AM

thanks tom and jack for the feedback...i thought i might of blew the feedback declaring my use of the laser pointer but i do know what your talking about...i dont own a multi meter but you mean a little hand held vu meter device....ill buy one....i never even owned one but honest...im well slick with a soldering iron from wiring god knows how many patch bays in recording studios so im sure ill resolve this niggle with your valuable input and my soldering skills thanks...

peter - Tue, Jan 21, 03 03:28:15 AM

sorry to be a pain but i just have to ask...i have a digital camcorder with a still pic facility...the pixel count is nothing to celebrate so long as you dont zoom in...theres an effect section and one of the effects is a negative setting wich makes it look like a negative...when i take a pic with the effect switched in and print it like that...playing that result back through the same effect sorta re inverts it back to a normal looking pic...might it be possible to photograph a real negative in some way from a roll of camara film then apply this effect to the pic to make it look normal on a screen or have i had one joint to many this evening thanks again people..

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