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power supply for a laser pointer

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ozgur84

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Hello everybody,

I am new in forum and I am not an electronic engineer. I am a physicist. nowadays I am building a lab equipment including a laser pointer for my experiments. the picture ot the laser pointer is here


I only have one of this laser pointer and it should bear until I finish my experiments. That's why I want to protect it from any current and voltage ripples or any possible effects can cause failure. I am planning to use 2 AAA size battery and a switch. I also measured the current of laser pointer and 30.6mA current flows over the circuit when I connect it to a 3V battery source. I am planning to use a 0.1uF capacitor between the terminals of the batteries.

I am looking for a simple circuit to do the job. I searched in the forum and I saw some masterpiece examples, however, many of them is quite beyond my knowledge.

So, thank you all in advance
 
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Bionic-Badger

Bionic-Badger

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You should find out, from wherever/whomever you bought that module, whether it has a driver already inside the module. It sounds like you've already operated the laser, so it probably does.

Batteries won't need capacitors, as they are pure DC power sources and don't have any voltage ripple. You only get ripples when using a voltage converter of some sort, like a wall wart or DC-DC converter.
 
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ozgur84

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Bionic-Badger said:
You should find out, from wherever/whomever you bought that module, whether it has a driver already inside the module. It sounds like you've already operated the laser, so it probably does.

Batteries won't need capacitors, as they are pure DC power sources and don't have any voltage ripple. You only get ripples when using a voltage converter of some sort, like a wall wart or DC-DC converter.
Click to expand...

I unfortunately lack of this information. it is not a high grade laser pointer for scientific applications. but it is hard to find in a short notice...

What should i do if i want to limit the current ? can i use just a resistor like 3V/Xohm = 30.6 mA ? or do i need something more sophisticated?
 
Z

ZeroLaser

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I was in a similar situation that your were in a couple months back. here are a couple links that helped me.

you can either buy for a relatively cheap price from the following link:
http://laserpointerforums.com/f67/driver-specifications-compendium-78942.html

or you can take a crack at constructing one yourself...maybe a simple linear one. an explanation of how driver work and link to DIYs and schematics are contained below. Also,if you decide to make a linear driver, remember they have cooling issues.
http://laserpointerforums.com/f51/i-want-build-laser-thread-52972.html

http://laserpointerforums.com/f67/how-laser-diode-drivers-work-explanatory-thread-71513.html




ozgur84 said:
I unfortunately lack of this information. it is not a high grade laser pointer for scientific applications. but it is hard to find in a short notice...

What should i do if i want to limit the current ? can i use just a resistor like 3V/Xohm = 30.6 mA ? or do i need something more sophisticated?
Click to expand...
 
LarryDFW

LarryDFW

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ozgur84;

If you just want a wall power supply for the pointer,

just find a ~3 VDC switching supply and wire it thru your switch.

I have a couple, if you need one.

LarryDFW
 
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B

blasterman

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I'm assuming ozgur84 has a 'pointer module' with the usual driver stuffed in the back and spring mounted on the end. It doesn't sound like we're talking about a bare diode here.

As per what LarryDFW said, I have a couple green ' pointer modules' I bought off E-bay that have been running fine off a 5v and 6v switched wall adapters for over a dozen hours solid. Actually the 6v is switched and the 5v isn't. Only issue is I have to keep a small CPU fan on them or power drops a bit as the driver warms up. So far, this is a better functional statistic than I've had with actual green diode modules encased in those black heat sinks with 12volt supplies. I'd rather run them this way for sure for constant use.

I hate to say 'mine run OK so yours should as well', but my understanding is the driver typically mounted to pen based green diodes drivers should be able to handle 5v (of relatively clean voltage) with no issues. 3v should run cooler. Any voltage ripples or spikes that get passed down from a switched wall adapter would likely be filtered by the driver and converted to heat anyways.
 
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ozgur84

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blasterman said:
I'm assuming ozgur84 has a 'pointer module' with the usual driver stuffed in the back and spring mounted on the end. It doesn't sound like we're talking about a bare diode here.

As per what LarryDFW said, I have a couple green ' pointer modules' I bought off E-bay that have been running fine off a 5v and 6v switched wall adapters for over a dozen hours solid. Actually the 6v is switched and the 5v isn't. Only issue is I have to keep a small CPU fan on them or power drops a bit as the driver warms up. So far, this is a better functional statistic than I've had with actual green diode modules encased in those black heat sinks with 12volt supplies. I'd rather run them this way for sure for constant use.

I hate to say 'mine run OK so yours should as well', but my understanding is the driver typically mounted to pen based green diodes drivers should be able to handle 5v (of relatively clean voltage) with no issues. 3v should run cooler. Any voltage ripples or spikes that get passed down from a switched wall adapter would likely be filtered by the driver and converted to heat anyways.
Click to expand...

Last time I could not upload the picture of my laser pointer but I think this time I succeeded :)

this is not a laser diode but a module that's why I also assume that it has a inbuilt driver module inside as you also said...

I did not try 5V until now and I use the 2xAAA size batteries because it is a more consistent power source.

Until now it worked ok. but before I was curious whether there will be a problem or not due to the voltage drop or higher currents...It does not heat itself too

thanks to your answer and if I have some heating problem I can also use a cpu fan as you do...
 

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