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ArcticMyst Security by Avery

How to use 50mA+ driver with <40mA laser

Cheater

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As the title stated, I think I need to find a way to change the output properties of a driver, so it meets my laser. Let me explain.

I have these simple and cheap diodes: search for number 590519565 in the AliExpress site.
In case the product page is not there anymore, here are some pictures and properties:

1598397238044.png 1598397273739.png

Operating voltage: 3V (I have 3V diode in my possession, but when necessary, I can order and use the 5V diode !!)
Laser wavelength: 650nm (Red)
Copper Head Diameter is 6mm
Light power: <5mW
Operating Current: <40mA
Operating temperature: -36 ~ 65
Shell Material: Brass

For a project, I want to control (and if possibly: dim) the lasers, so I have found a driver that supports TTL.
Laser driver on AliExpress: search for number 32917078037 in the AliExpress site.

1598397748925.png

Specifications of the driver:

Voltage: 5V
Current: 50-300mA (Can only drive power at 20-200mw, less than 10mW will burn the pipe)
Suitable laser Diode: 50-300mW 660nm 780nm 808nm 850nm 980nm
Tips: if you do not need TTL function, you need to short circuit power"+",and TTL"+"
Size: 2x1cm/0.79x0.39inch


However, the documentation clearly states that output power is at LEAST 20mW (or at least 50mA).
Now this is too much for the laser because it wants 40mA or lower.

Main question: Is there a way to achieve to get 40mA or lower with this driver, by adding electrical components to the output of the driver? If so, how? If only components are mentioned, I don't know how to wire them, because my knowledge level with this is rather low.

Alternatively, if anyone knows a (cheap) driver that supports TTL and a can hook up that laser diode I specified, I'm happy too.
 





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You can use a resistor in parallel with the laser diode, NOT in series but in parallel to essentially waste 10mA because your driver is going to adjust to maintain 50mA.
 
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I dont think you need a driver with these as they are intended to run of 3V using the onboard resistor seen in the pictures. If your TTL source can drive 40mA directly then just add a 56-62 ohm resistor in series with the laser, if it is 5V TTL. If the TTL source can't supply 40mA, then also use a transistor to drive the laser.
 
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Cheater

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So you say, I can drive such a laser with only an arduino or so? That would be great ofcourse, since that reduces the complexity of my project. I need to control around 12 lasers individually.
However, I hooked them up to a 3V power supply, and the laser is now fainted, so I don't think it can be powered directly without a proper driver.
 
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Operating voltage is clearly stated to be 3V, and that it will draw less than 40mA. Verify that that you actually supply 3V. If the laser break at the rated supply then you need to contact the seller.
 

Cheater

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Funny that you ask. I'm building a light-show in a small garden.
In the soil, 12 pvc tubes of 50mm arise a bit above ground-level. Via a pipe system underground, mist/fog (real water mist) is transported and pushed out of the 50mm openings. The openings have custom made valves on top of them, to open or close the pipe outlet. Also the valve can be rotated, and a small mirror is attached to the valve. In the pipe, 1 (or 2) lasers will be fitted, along with 2 RGB leds. The mirror will redirect the laser, which will be visible within the area where the mist/fog is. The show is completed with a 10 meter RGB led strip with individual programmable leds and 5 wall lights that are also individually controlled in brightness. The show is build around aquanura, a show from the Efteling here in The Netherlands.
 
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Buffo

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I applaud your ambition, but given how much other light you will have in your planned garden show I am concerned that 5 mw of red is not going to be nearly enough.

Also, using water-mist fog is going to make things worse, as the fog dissipates very quickly. And without some scattering medium those 5 mw red beams are going to be completely invisible, even if your garden is completely dark (which it won't be with all the extra illumination provided by the planned RGB LED strip lighting, LEDs in the tubes, and wall-mounted lights). You will be far better off with a true hazer using either mineral oil or glycol-based haze fluid.

I suggest you perform a test at night in your garden. Lay out a few meters of your strip lights on the ground and turn them on. Then turn on one of your wall - mounted lights. (If you haven't mounted them yet, just set one on a chair nearby and power it up.) Now put your water-haze generator in a bowl of water and turn it on. When all of that is running, shine the beam from a <5 mw red laser pointer around the yard and see how visible the beam is. Also note how the water-mist fog doesn't travel very far from the bowl of water... Then you can decide if this is close enough to the plan you had in mind.

Adam
 

Cheater

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Hi Adam,

Thank you for your reaction. You think along well which really helps me.

Since I did not any testing (yet), with the laser in the fog/mist, and after reading your message, it was time to actually DO a test with the 5mW laser. I made a video about the visual test, and I'll see if I can share it with you here.

You are right about certain things, but also you've made some assumptions which I counter.
The mist production DOES carry far and stays in the air, but it depends on the conditions. I do not use those silly small 1 or 3-head foggers which you place in a fishbowl (or so) indoor. My experience is: On a sunny day, in the sun, the water-mist evaporates very quickly and after a few seconds the mist that came out, is already gone. Nothing builds up. However, in the evening, when it's a bit colder and when not much wind exists, the mist stays and actually builds up in the area. First at floor level (because it's heavier, like normal mist in the open fields in the morning), but when it builds up, it quickly builds up as high up to a meter in my kitchen which is around 2.5 meter by 2.5 meter in a minute with only one 10-head fogger. I have two of them and may expand to 3 when the mist is not generated quickly enough. So I'm fine with this fogger and I don't need a hazer.

About the visibility of the 5mW red beams, you are correct. It really isn't enough powerfull to be of any meaning. Only 30'ish centimeter of beam is visible which is really not enough. This is the result of the fog so very dense, that the laser will be blocked by those many water droplets in the air and the 5mW beam is too weak to punch through that fog. I could have known, but my experience with lasers are scarce and limited to only toy-lasers.

So, this test is a succes for me. The outcome was not what I hoped for, but now I know, I need a more powerfull laser which is still quite small because I need to fit it in a very small housing. The 5mw laser you see above were ideal for this, but they are of no use now I've tested them.

Any advise on a laser (color doesn't really matter, although it needs to be visible for the eye ;) ) which is a bit more powerfull and still very small in footprint? Oh and please it must be cheap, since I need 12 of them. If possible, I really want to ONLY fit the diode in the housing, because of the fog + electronics. The electronics will be placed where the fog does not reach.
 

Cheater

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I did some quick searching, and found a Dutch website (may not be the cheapest) but since it lays out various laser diodes, it's my initial reference to search for a diode that is suitable for me.

It's a Dutch website, so enable the auto-translate if necessary. (I needed to add some spaces because otherwise I couldn't post a link)
www. laserkopen. com/c-40_102.html

What mili-wattage do you advise me to search for? I don't need a diode to light up the clouds, but strong enough to be make a nice 'wow' when I execute/play the show.
 

Cheater

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They advise me this laser:
www. laserkopen. com/c-40_102-p-10155.html

Only because they don't have a 50mW (or so) red laser.
I hope I won't burn things with 100mW because that is really not what I want. It must be safe to have this laser in a show, and don't burn plants.

1598795617717.png

Specsheet:
1598795628583.png
 

Buffo

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Thanks for sharing the results of your fog test. Although I'll caution you that the water fog performance in your kitchen (where the air is still) will not reflect the performance in your garden (where there will likely be some wind).

Regarding the visibility of different laser colors, red is the worst. The peak of human color vision is around 550 nm (bright green) when in brightly lit conditions, but as the light level fades away the color peak begins to shift towards the blue end of the spectrum. Still, even in complete darkness you'll almost always find that any green laser will appear brighter than the same amount of power in either red or blue.

So if apparent brightness is your primary goal, then stick with green diodes (520 nm). ;)

The 100 mw red diodes you posted will appear much brighter than the 5 mw units you had originally selected. And no, they shouldn't damage any plants. However, you wouldn't want to get hit in the eye with the beam. Just make sure they are directed in a safe direction and you should be fine.

The real question is, "how much power do you need", but the answer depends on many factors: how much fog you will have, the angle that you will be viewing the beam, and how much other light will be present in the garden. 100 mw of red *might* be just enough if everything is very dark and the fog density is perfect. 100 mw of green will look much brighter though. (approximately 4 to 5 times brighter, in fact)

I think before you start building your display you might want to purchase a few individual diodes of varying power and wavelength and then do some tests to see just how visible they are in your garden at night with the other lights running. I'd hate for you to build the whole display only to discover that the lasers are too weak to be seen. Have a look at DTR's Laser Shop for some idea on pricing.

Adam
 




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