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Question regarding driver and wiring config for my application

defdwight

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Hi guys, I've been reading several threads on here regarding wiring and driving multiple lasers and wanted to see if anyone could help guide me on my specific application. I have been tasked with designing and building a custom light piece for a band using lasers but unfortunately my circuit design expertise does not span into the area of lasers. Any help is greatly appreciated!

Basically, this piece will have 8 green lasers shooting into a spinning prism to effectively scatter the beams around in 360 degrees. It will only be on for one song in each show, and only for about 30 seconds or so. I have already mocked up a prototype fixture and experimented with differing angles and so forth. The concept works and I'm at the point of building out the rest of the fixture and wiring it all to run off a 12v battery. I'm not 100% confident on what I should do regarding the laser driver circuit though, which is where I need assistance.

I do not have a datasheet for the lasers I am using unfortunately. All of these modules were pulled out of "Star Night Laser Dancers" (only the green lasers). However, I do observe in the Laser Dancers driver circuit that they are running at 3.1v-3.3v and using an ammeter I measured the current for each laser module to be at 145mA-150mA. Since I do not have physical room in this fixture to run a separate driver for each laser, I need to run multiples on a given driver. I feel like given the "typical" LD forward voltage of around 1.5v-2v (which I can only assume since I can't determine what LDs these are and therefore have no datasheet), I won't be able to run all 8 on a single driver due to power supply voltage limitations. So I am leaning towards 2 drivers powering 4 lasers each.

Based on what I have read here, it looks like I should wire the lasers in series. Can anyone provide some guidance on driver selection and wiring? As it stands now, my 12v battery will be running into a 5A adjustable buck converter. Max safe voltage output setting will be 9v given the 12v input. Is the buck converter overkill for voltage regulation? Should I just run the drivers off the battery? I'm very green to this, which is why I ask.

If I'm understanding what I've been reading correctly, I'd need the driver to get around 8v-9v and regulate current at 0.6A for 4 of these lasers to operate at 150mA. Is this a correct assumption?

Again, any help is GREATLY appreciated. Thanks so much in advance.
 

paul1598419

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According to Kirchoff's laws, the current through any series will be the same for each diode in the series. So, though you need to add the Vf for all the lasers, the current will be the same as if you were driving one diode. This is a bad idea. That is because lasers are an eyesight hazard and you run the risk of blinding people if you don't know exactly what you are doing. I know there is a WOW factor for using lasers in shows, but they are tightly regulated in the USA.
 

diachi

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According to Kirchoff's laws, the current through any series will be the same for each diode in the series. So, though you need to add the Vf for all the lasers, the current will be the same as if you were driving one diode. This is a bad idea. That is because lasers are an eyesight hazard and you run the risk of blinding people if you don't know exactly what you are doing. I know there is a WOW factor for using lasers in shows, but they are tightly regulated in the USA.

^^This. Hire a professional, or spend the time and money on getting trained yourself.
 
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