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Powering 2 lasers from 1 power supply

ivanpianobcn

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May 11, 2014
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Hi there.

I'm trying to power different 50mw lasers (2 at the moment, but I want to power 9).

As you know, Pc power supply gives you 3.3, 5, and 12 volts. In my power supply I have 5 orange wires, that supply 3.3 volts.

If I connect one laser directly to the power supply, (orange wire to positive and black wire to negative), it works well, but when I connect a second laser the same way, using another of the orange and black wires, the intensity of both lasers is much dimmer, and they switch on and off very quickly.

I guess there's a problem with the current each laser is receiving, but I don't understand why, because the power supply is capable of giving 12 ampers in total on the 3.3 volts circuit.

Any ideas?

Thank you all
 

Cyparagon

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Measure the voltage input to the first laser, before, and after connecting the second laser. If it drops, you know it's a power supply issue.

ATX PSUs typically need a medium load to be stable on some rails. The standard fix for this is putting a power resistor on the 5V rail. 4.7ohm 10W or something like that should work. An Automotive halogen lamp should work, too.
 

xirrious

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Aye a multimeter will tell you what is wrong. PSU's are cheap though for low power ones which is all you need for some lasers. That is odd I'd agree. Cyparagon as usup gave solid advice. I'd get another psu if I was you. They should all put out current according to specs regardless of what's connected to other rails .. think what this would do to you PC if your psu dropped it's output when your gpu connected to it revved up and dropped power to say your cpu.. bad news. Get a new power supply.
 

Benm

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I'd agree with that - don't use PC power supplies for this application. They can work but a prone to a host of problems under such loads which sometimes could even damage your lasers.

If you want a nice compact switching mains supply, look on ebay. You can find switching supplies with 3.3, 5 or 12 volt output at 10-20 watt output levels for $10 or so.
 

ivanpianobcn

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May 11, 2014
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Measure the voltage input to the first laser, before, and after connecting the second laser. If it drops, you know it's a power supply issue.

ATX PSUs typically need a medium load to be stable on some rails. The standard fix for this is putting a power resistor on the 5V rail. 4.7ohm 10W or something like that should work. An Automotive halogen lamp should work, too.
Thank you all for your help and advises.
Cyparagon you were right on! I added a fan to the 12 volts rail, and I'm powering the arduino and a camera with the 5 volt rail, and it works well now.

For the moment, I'm going to keep this PSU powering all the lasers, fan, and arduino stuff, but I'll look into other solutions.

What I'm seeing now, is that after 10 minutes of being everything on, the lasers are getting a bit hot, and become less bright. I guess if I just use the fan (maybe more than one?) cooling the lasers, everything should be alright. Any thoughts here?


For those that are curious about what I'm doing:
A laser harp, with a camera, and each beam has its own laser.

Thank you all again
;)
 

victorx10

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May 27, 2014
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Powering infrared Line Laser using USB port
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Hi,

I have a line laser which has following specs!!!

Aliexpress.com : Buy 780nm 60mw 5V IR Infrared Laser Line Module 120 degree from Reliable laser line module suppliers on Emma Technology Co., Ltd.

5V DC or 3.3V preferred!!
Working current must be < 200mA

How can power this laser using USB cable or USB port

I know USB has 5V DC (max current is 500mA)

I want to know how to convert it so that i can power the laser??!!! Thansk in advance for help!!
 




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