Slight overdrive on a generic pointer working so far...

I bought this from lazerpoint.com a few years ago. It was labeled as 100mW and I liked the green shell instead of the standard black rubber grip these pointers usually come in. I spent almost thirty bucks and was pretty let down. I didn't know lasers then like I do now so laser scams weren't something I had dealt with before; lesson learned! This thing can't be more than 50mW. I have no power meter, but this laser was pathetic. Literally nothing compared to a 405nm wicked laser nano and those are supposed to be 75mW. I put this laser down in disappointment and just yesterday picked it back up with an idea. Instead of two AAA batteries, I used one rechargeable 10440 3.7v cell and a dummy cell. That extra .7v really made a difference! Noticably brighter (beam and dot both) and it even gets SLIGHTLY warm. I love my result, but how bad do you guys think this is for the laser? Thank you for looking and I hope for some good input on this!

It's hard to say - apparently there is not much of a constant current driver in there. I suppose there must be something that boosts the voltage to get a 405 nm laser working, but somehow it doesnt regulate, very odd.

As for how bad it is for the laser diode: it's driven harder than designed for,that is always a risk.

Btw, how do you know this laser was not over 50 mW? 405 nm light is deceptively difficult to see. I have one that does about 200 mW and the beam or even dot is noting to speak of - sort of like a cat toy... unless you hit something fluorescent and you see a -very- bright dot (blue on paper, various colors on other items).

Benm said:

It's hard to say - apparently there is not much of a constant current driver in there. I suppose there must be something that boosts the voltage to get a 405 nm laser working, but somehow it doesnt regulate, very odd.

As for how bad it is for the laser diode: it's driven harder than designed for,that is always a risk.

Btw, how do you know this laser was not over 50 mW? 405 nm light is deceptively difficult to see. I have one that does about 200 mW and the beam or even dot is noting to speak of - sort of like a cat toy... unless you hit something fluorescent and you see a -very- bright dot (blue on paper, various colors on other items).

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I could definitely be wrong! 405nm is so hard to make assumptions about when only using your eyes. But an old friend had the 75mW 405nm nano from wicked lasers and it was noticeably brighter and stronger than my laser. I guess that made me assume it was for sure below 75mW. I have a 200mW 405nm pointer from Sanwu and it's also brighter than this laser by far. That's all I have to go off of D:

That battery fully charged is more like 4.2 VDC than 3.7. You might be shortening the life of the diode considerably. It doesn't seem to regulate current as well as it should, but many cheap 532nm don't either.

paul1598419 said:

That battery fully charged is more like 4.2 VDC than 3.7. You might be shortening the life of the diode considerably. It doesn't seem to regulate current as well as it should, but many cheap 532nm don't either.

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Hmm it'll be interesting to see if this laser will actually hold up. It's heavier than majority of the pen style lasers like it so maybe it has a decent component or two in it. I don't have the highest hopes though since 405nm diodes have this thing they like to do to me. They work so good I think I have a better unit than most & next thing I know they die -___- I'll take fault for when this one dies since I'm driving it hard, but idk why I have such bad luck with other violet lasers!

paul1598419 said:

That battery fully charged is more like 4.2 VDC than 3.7. You might be shortening the life of the diode considerably. It doesn't seem to regulate current as well as it should, but many cheap 532nm don't either.

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So if this laser could regulate current appropriately does that mean my battery swap wouldn't have made the laser stronger?

As long as the battery voltage didn't drop below the necessary minimum input for the driver to apply Vf to the diode. For some boost drivers, 3 VDC is too low for Vf for the diode.

I reckon there must be some sort of boost mode power supply in there, even two fully charged alkaline cells combined only give 3.0, maybe 3.2 volts, which is too little to power up a 405 nm laser diode.

As alkaline cells sort of go from 1.5 volts when fresh to about 1.0 when mostly depleted it should work anywhere between at least 2 and 3 volts input voltage. This would be a boost mode converter, which has a diode between input and output. So even if it's doing nothing at all with 4.2 volts output plus about 0.3 volt diode drop (assuming it's a skottkey), there shoul be no way for this lithium cell to forcibly drive the diode.

I have no idea what driver circuit is in there, but it surely seems to be a poorly designed one.

Benm said:

I reckon there must be some sort of boost mode power supply in there, even two fully charged alkaline cells combined only give 3.0, maybe 3.2 volts, which is too little to power up a 405 nm laser diode.

As alkaline cells sort of go from 1.5 volts when fresh to about 1.0 when mostly depleted it should work anywhere between at least 2 and 3 volts input voltage. This would be a boost mode converter, which has a diode between input and output. So even if it's doing nothing at all with 4.2 volts output plus about 0.3 volt diode drop (assuming it's a skottkey), there shoul be no way for this lithium cell to forcibly drive the diode.

I have no idea what driver circuit is in there, but it surely seems to be a poorly designed one.

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Yeah being from lazerpoint.com I'm sure everything is as cheap as it could be inside this laser. I was stupid and paid extra for good shipping but other than that it's still just a cheap generic Chinese pointer. Can't expect too much I suppose!

It's more a matter of bad design than of being cheap really.

A decent constant current source takes about 2 transistors and 2 resistors to build, just a few pennies worth of components. It could actually be cheaper than whatever they have constructed in there.

The problem is R&D cost more than component cost, even for mass produced items.

It sadly is a problem with many chinese suppliers, even ones that do large volumes. They could pay a proper electrical engineer $1000 to work for 2 days and find ways to improve the product without adding cost, but they often just opt not to.

The reasoning behind this is that they are far away from the consumer and will not get into any problem if their products all fail in 3 months or something like that. These items are so cheap you'll probably not even put in the effort to reclaim your money, and if you do it'll take you a lot of work through paypal or credit card companies to reclaim that couple of dollars.

You could, however, try, as credit card companies will probably rather give you back your $10 or so without investigating further, spending 5 minutes on the matter is more expensive to them. Same thing goes for insurances and such, as long as your claim is small they're unlikely to spend any time looking into the validity as that costs more than the claimed amount.