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building a 5W laser with a Laser that comes with a 12V PSU

Mannitu78

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hello,
id love to post a link here but im not allowed yet. Ive spotted a 5W Laserdiode inc. a big black heasink with fan and driverboard is already attached, a 12V Powersupply also comes with it. For sure you are familiar with this lasers, they are sold for this carving/burning/cutting machines. However i want to build it into a handheld laser but the driverboard confuses me a little bit. I understand the pins for "12v" which is for the PSU and "5volt fan" and "LD output" which are all obvious. But there is a 4th slot with 2 pins for "0-5V TTL"? What is this for?

Because id like to use batteries, must i connect them into the slot for the 12V PSU? And if so, i only have 3,7V Batteries, so i could only create 11,1V or 14,8V, i guess 4 Batteries resulting in 14,8 Volts would be ok?
 



RedCowboy

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Many of those drivers will operate well outside of the listed 12v, I expect 3 x 18650 in series would do just fine.
The TTL is transistor to transistor logic so you can modulate it via PWM but you can usually leave it unconnected and it will work at full brightness.
 
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Mannitu78

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one more thing, i just figuered out that i got 2 unused battery-packs for handheld akku-drillers here. It would be nice if i could just use them, because they are already in a nice black casing...one is 18V and one is 14,4 Volts. What would happen if i put the 14,4V on the driver? can it also handle higher voltage?
 

RedCowboy

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I can't guarantee anything but you could test it with a dummy load........however you could also blow it.

If it's rated at 12v input then I would say your safe with 3 x 18650's in series because even though they float fully charged at 4.2v each ( 12.6 for 3 in series ) they will sag under load and those power supply's will typically regulate at less than 12vin and do have some leeway over but how far over you can go I don't know, depends on how they were set up......12.6 floating I would not worry about ...........but 14.4v or 18v I can't say, probably not a good idea to try the 18v pack but the 14.4v I bet will work ( A lot of 12v stuff sold to the US will be used on automobile battery power which is 13.8-14.4v when running ) and with a 5w diode to drive you will have some battery sag under load so you might get away with the 14.4 pack but AT YOUR OWN RISK.........If you look at this Chinese driver you will see it says 12v ( 9-18vin ) so you could buy this driver or take a chance with yours betting it's similar which it may be but I can't guarantee it.

You could open your pack and make it close to 12v by removing some cells, what are they ? NiHM ? NiCd ? if so they are 1.2v each cell so 10 cells in series will give you 12v

You could also make a simple linear current regulator if not using your laser for a CNC but I would turn the 18v into 9v by rewiring it series parallel if making a linear current regulator ( closer to your needs to waste less power ) now if you want to repurpose the driver 12.6v is likely fine, I have some 12v Chinese drivers running on 3x18650's and they are quite happy, I have also tested them and seen that they regulate with as little as 7.5vin but I can't guarantee what yours will do, also you need to supply enough current from your pack for your 5W laser, probably best to aim for 12vin or step down to 12vin, you can buy a switching type dc to dc cheap on ebay to use on the input side of your driver but don't drive your laser with the cheap dc to dc or you will pop it as they spike on start up.
 
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