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Calling all Tech Gurus - New 5mw Circuits from China

Keo2

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With the price of green-lasers dropping so low on the ebay lasers from China (I got this one for $4.50 with free shipping, impressive 10-day ship time to rural midwest USA too), I thought I'd get one recently to see how they are. The new ones no longer have an easy to adjust potentiometer on the circuit-board. So I was wondering if any of you electronics geniuses could take a gander at the circuit and see if there's a way to patch in a little pot or maybe even just a solder-bridge across an SMC resistor to take it out of the circuit to up-the-ante on these things.

Rather than risk ruining it to remove the works, I used a fine-blade x-acto saw to cut the barrel lengthwise for easy removal (will use friction-tape around it to restore the pressure-fit later).

Here's the overview of what you'll find inside. The little black-plastic saddle slides onto the circuit-board to hold it centered in the housing.

7023044243_c54ed7369d_b.jpg


An interesting finding, the threaded part to which the battery section screws into, is actually a pressure-fit threaded ring. Showing this because if you try to slide the works out through the battery-case end, it won't go unless this bit is slid out first.

7023044247_bb82ec51d7_d.jpg


Here's the top (switch side) of the PCB. (sorry about the blur, hand-held photography camera-shake) Diode to the left, battery-contact spring to the right (in case that's not obvious to everyone).

7023044251_ae626ced13_b_d.jpg


And the more interesting bottom of the PCB.

7023044253_dc3caebeab_b_d.jpg


So .... does anyone see a simple way to change these from 5-10mw (mine seems brighter than the sold-as 5mw), to the standard-issue pot-modded type that puts out 100mw or more? (if you'd like, feel free to markup and repost any photo showing where the mod needs to be made)

My 2-3 years old pot-modded lasers (still working strong) a purple and green one, are nice. My purple pot-modded one must have much less IR filtering, it can light a match quicker than anything, even if the match hasn't been blackened with a sharpie. The green one's beam still clearly visible in a day-lit room. I found that when showing the green one to someone that you have to make a light-saber sound when waving it around.
 





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You should do a bit more reading about pot modding.t
Basically you can't pot mod green lasers anymore. Green lasers that you find on Ebay are already putting the maximum amount of green light they possibly can. If you attempt to pot mod one of these newer green lasers you will most likely destroy it or cause unwanted modes to appear.

However some diode lasers on Ebay CAN be pushed a bit further but I wouldn't suggest messing with them unless you know what,current they are already running at.

Also just to let you know, only GREEN lasers output IR. They do this because they are pumped with an IR diode. Basically you shouldn't need to worry about IR unless your dealing with DPSS lasers. ( Diode Pumped Solid State, look it up)

I wouldn't recommend messing with that laser you have either. You will destroy it.
 
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He's got $4.50 in it. Why not?

I don't know which resistor you need to fry or replace or whatever, but you might search YouTube.

I'd love to get some of those if they are really 5mW!
 
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He's got $4.50 in it. Why not?
^It swings both ways. How much can you really expect from $4.50?

Looks like you typical comparator circuit. Drive transistor on the top, 1ohm sense resistor, lm358 op amp...

You can change the sense resistor or the divider resistors or perhaps the voltage reference. LOTS more trouble than it's worth.
 
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Why would "tech gurus" waste their time on such a useless application? Just but a better laser pointer. You'll probably end up burning that laser out anyway.
 
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Well you could use the crystals with a higher power diode as long as they have a good damage thresh hold
 

Jaseth

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My purple pot-modded one must have much less IR filtering, it can light a match quicker than anything, even if the match hasn't been blackened with a sharpie.
Violet lasers are not IR filtered. Only DPSS lasers need filtering.
Shorter wavelengths (violet from blu-ray drives being the shortest visible one I know of at 405nm) are more readily absorbed by light colour materials which explains why it is good for burning matches and white paper. The fact that is has very low visibility may also explain why it is more powerful than your expect.
The green one's beam still clearly visible in a day-lit room. I found that when showing the green one to someone that you have to make a light-saber sound when waving it around.
I hope you and your friends are wearing goggles when you are "waving it around" as well as for the burning.

only GREEN lasers output IR.
I assume you just worded this wrongly, but I want to clarify to anyone else reading the thread that there are several other DPSS lasers than green ones - the most common being 473nm, 589nm and 593nm. All of these should be IR filtered.

Well you could use the crystals with a higher power diode as long as they have a good damage thresh hold
I doubt the cheap crystals they use will be able to handle much power. Not enough to warrant a difficult and time consuming project such as realigning them anyway.

I recommend listening to Cyparagon and Bionic-Badger. Not just in this thread, but in general.
 
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^It swings both ways. How much can you really expect from $4.50?

Looks like you typical comparator circuit. Drive transistor on the top, 1ohm sense resistor, lm358 op amp...

You can change the sense resistor or the divider resistors or perhaps the voltage reference. LOTS more trouble than it's worth.

Nice post, you let him know why it is probably a waste of time, but you also gave him some pointers so he can give it a try. Lots of learning to be had from trying things that don't work!

+1
 

Keo2

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^It swings both ways. How much can you really expect from $4.50?

About the same 120-150mw I got from the last $8 laser pointer from 2-3 years ago and is still going strong? :)

Looks like you typical comparator circuit. Drive transistor on the top, 1ohm sense resistor, lm358 op amp...

You can change the sense resistor or the divider resistors or perhaps the voltage reference.

Which would you suggest to be the best one to fiddle-with? When first powered on it looks to be putting out about 50-80mw (quite impressive actually, looks to be about 1/2 to 3/4ths the power of my previously pot-modded burners), then slowly ramps down (in 5-10 seconds) to somewhere around 5-10mw. As it warms up it increases to about 15-25mw. (rough guesses on past experience with trying to deduce power-outputs from how fast they can light a match and beam-visibility in the relative brightness levels in the room, as reported by others, I'd say my guesstimates are pretty close)

If it could be kept at its starting power, that'd be great. It's just that ramp-down afterwards that lasts about 10-15 seconds, flickering as it's adjusting, that's annoying. Then it staying at about 5mw for awhile. Then after about 30-60 seconds it gets up to that 15-25mw (possibly more than that, rough guesstimate).

Considering how bright it is after full warm-up, I'm tempted to leave it ... but it's ONLY $4.50 worth of experimenting. Plus this could help lots of others who are unable to get better lasers through the mail if it works.

LOTS more trouble than it's worth.

Not if you live, as so many do, where you can't get lasers rated more than 5mw unless you build from scratch and this is your ONLY option. I'm also an amateur astronomer and wanted another higher-power one for when out stargazing and having to point out things (airspace permitting). Handing one to another person at the same time makes it much easier than saying "That one over there? Or over there? Wait, use my pointer...", handing it back and forth. Plus I really intended to adapt it for a rifle-sight (replacing the red module in my existing laser-sight) for daytime use, since it was so inexpensive and expendable if I screwed up something. Will get another one for that if this works. (invasive-species vermin problem here) That was the first reason I went ahead to see how the new ones are built for $4.50 these days. Would hate to have to depend on it for humanely shooting vermin when it's stuck in that intermediate very low 5mw area. Quite possible that would happen a lot considering how a laser-sight on a rifle is used -- intermittently but sometimes powered-on/off often.
 

Jaseth

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635 nm lasers don't output IR. They're diode based ones...
Thanks for pointing that out. I was aware that the ones currently being built by hobbyists use a diode, but I could have sworn I saw a 635nm DPSS on CNI a couple of months ago. Here's one that claims to be DPSS anyway 635nm 200mw Red DPSS Laser - China 635nm 200mw Red DPSS Laser Supplier,Factory - Xinland International Limited
Then again it also claims to have a 'Beam detergency' of 2mrad. I guess it's good for cleaning :wtf:
 
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About the same 120-150mw I got from the last $8 laser pointer from 2-3 years ago and is still going strong? :)

And with what duty cycle?

Not if you live, as so many do, where you can't get lasers rated more than 5mw unless you build from scratch and this is your ONLY option.

Then those people can find a laser pointer that already has a pot attached and fiddle with it directly. Reverse-engineering some driver on a $4.50 laser pointer just so that you can solder another pot--that itself is probably worth a significant fraction of the laser pointer's cost anyway--it just seems like polishing a turd.
 

Keo2

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And with what duty cycle?



Then those people can find a laser pointer that already has a pot attached and fiddle with it directly. Reverse-engineering some driver on a $4.50 laser pointer just so that you can solder another pot--that itself is probably worth a significant fraction of the laser pointer's cost anyway--it just seems like polishing a turd.

Then it appears I've come to the wrong place. This clearly appears to be a front for laser RE-sellers (who buy all their stuff from China in the first place) to con people out of their money.

Silly me. I thought perhaps this was a forum where people freely exchanged ideas to help one another and to further the education of humanity, not just a front to make money for con-artists.

I guess I was wrong.
 
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Then it appears I've come to the wrong place. This clearly appears to be a front for laser RE-sellers (who buy all their stuff from China in the first place) to con people out of their money.

Silly me. I thought perhaps this was a forum where people freely exchanged ideas to help one another and to further the education of humanity, not just a front to make money for con-artists.

I guess I was wrong.

That is not true, there are just a lot of people here who frown on pot modding greens for good reason.

However, Cyparagon gave you a complete answer. Why not try his suggestions and ignore the people you don't agree with?

You will be very hard-pressed to find a better laser forum out there.

No matter where you go, you will find some people who you get along with and others that you don't. Learn to cultivate the relationships with the people who you get along with and try to avoid the ones you don't.

Don't be a baby about it! :)

P.S. Your comment about "This clearly appears to be a front for laser RE-sellers (who buy all their stuff from China in the first place) to con people out of their money." is shockingly ignorant. Really, you should be embarrassed for yourself. Go to the buy sell and trade section, or the do it yourself and see that people here are building their OWN DESIGNS of drivers, using raw diodes and even machining their own hosts. Your statement isn't even remotely correct.
 
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