How to wire multiple laser diodes

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cgc210
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How to wire multiple laser diodes

Trying to wire 50(resisted) 650nm, 5mw red laser diodes. Need help with serial/parallel configuration & volts/mA source. Would like to use as low of a portable (battery) voltage source as possible, not over 9 volts if can.

Previously wired 40(same) 10 rows of 4 in serial/parallel array. Everything works, however some are very bright & some not so bright. Can anyone school me on how to do this correctly for maximum brilliance. Powered the 40 with a 15 volt, 4 amp wall wart.

Grateful for any help TY much

cgc210

Photon Master
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I’m really interested in lasers myself. I’m curious to know what you’re building? I knew a guy who could assemble multiple lasers using some kind of mirrors or prisms to combine the beams. He said he could build me a 40 watt blue laser rifle for like $2,500 but it was too steep.

Lightbringer
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“Hey, just what you see, pal.”

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Sunnysunsun
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I think you need them in series to have a chance at having a similar brightness. Maybe use a cheap boost driver from aliexpress. Lasers are very sensitive to voltage changes, and wiring them in series will keep current the same.

Photon Master
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I also saw a video on YouTube made by StyroPyro where be aligned red, green, and blue beams to make a white laser. It was really cool and it made me wonder if someone will do something similar to make a true white laser flashlight

cgc210
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Sunnysunsun
Thank you very much for replying.
Presently I have a 40 diodes connected in an array of 4 in series of 10 sets, that are then paralleled together . The array is powered by a 12 volt, 1 amp wall wart. All light up but I notice that when the unit is turned on many diodes are very bright and some are not so bright. After a while many of the bright diodes have dimmed. The only resistors being used are the ones that the laser diode is equipped with. This is a little confusing for me. Obviously the diodes are protected by the resistor, but I don’t know if additional resistors should be added to even the distribution of current.
Any thing you might be able help with would be appreciated. You are correct lasers are very sensitive (the cheaper they the more sensitive they seem) as I have learned. Fortunately, they are also inexpensive. Again, I would appreciate any input you can offer.

PS I have many LED drivers. Do you know if an LED driver can be used with laser diodes?

Thank you cgc210

cgc210

cgc210
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PM
Thank you very much for replying
I am putting together a laser wand. You are so very right, $2,500 definitely raises one’s eyebrows and kind’ve makes you cough a little. After working with LEDs I have recently been asked to make the wand. One of the problems I have found is that I thought the resistors on the laser diodes would even the current among the individual diodes. The 40 diode wand that I put together works, but I think it should perform better. When the wand is powered many of the diodes light brightly and some not so bright. After about 5 – 10 mins some the brightly lit diodes begin dimming.
The wand array: 40 diodes
4 connected in series
10 sets paralleled
12 volt, 1 amp DC transformer

I am open to any constructive help and sure would appreciate it.

Thank you very much cgc210

cgc210

clientequator
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Laser diodes are similar to leds basically, and they are current devices not voltage devices, so you need to drive them with a constant current source.

Many flashlights here use 3 or 4 led in parallel with no current sharing circuit so it is actually very bad practice to do, but it is helped a bit because the leds used are quite well binned and they are quite durable, but you will not see any ‘professional’ product doing parallel led without very carefully binning (such as in 2s2p emitter like xhp70), or proper current sharing circuit.

I do not know what you mean by your ‘resisted’ laser diode. If you are using raw diode and they are all the same, you can wire them in series and run them with constant current circuit. It may be possible to use a big resistor for each parallel string. If your diode are going dim after a while, they may also be overheating. Laser diode usually much more fragile than led and need much more accurate current control for brightness, and voltage control to prevent damage to diode.

cgc210
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clientequator
Thank you very much for replying. This is my first experience with laser diodes, but have much LED experience and as you say LED & lasers are similar. I suspected as much and sort've guided myself with my LED knowledge.

By "resisted" I mean the laser diodes arrived with resistors already installed on them. The 5 volt diodes have a SMD 910 resistor & the 3 volt diodes have a 330 SMD resistor on them. The problem is that I don't know how to calculate any "resistance" inclusive of the existing resistance they came with. Any additional input you may have would be much welcomed.

Thank you cgc210

cgc210

Lightbringer
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If we’re talking plain laser diodes, they all individually need to be run via a driver, because there’s a narrow range between lasing at all and cooking itself. Each driver likely has a connection for a feedback diode to sample the output and drive it correctly.

If we’re talking laser drivers, they should all be run in parallel, so that each one can minister to its own diode correctly.

Sticking ‘em in series means that one which draws 100mA and another which draws 110mA will end up starving the hungrier one. And being that they’re nonlinear loads, the individual voltages across each driver will vary quite a bit.

Stick ‘em in parallel.

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cgc210
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Lightbringer
Thanks for replying. I want to be sure that I understand, are you saying to connect each laser diode to it’s own driver? Or, can one driver run several diodes (hopefully more). Also these laser diodes came already with a resister. The resister is problematical in that I don’t know how to calculate the resister in parallel with the diodes.
Thank you cgc210

cgc210

Lightbringer
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You talking about these little doodads?

If so, they have their drivers built-in. Just connect all reds together and all blacks together.

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cgc210
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Those are the ones. They have their won resistors how much protection is provided. Do you just continue adding voltage & (current) based on the requirements of the number of diodes?

cgc210

Lightbringer
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They shouldn’t be just resistors inside, but some kind of actual driving/regulating circuitry.

You gotta check what you bought. Some might be 3V, others 5V, etc.

Or, just plop ‘em in series and keep hiking the volts ‘til they’re “bright enough” without going pouf.

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cgc210
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It would indeed be nice if either the 3V or 5V diodes came with more than just the resistors, but that is how they came. My concern is getting/keeping the lasers bright enough and getting/keeping the voltage/current balanced throughout the array.
Thank you very much for the input.

cgc210

cgc210

Lightbringer
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Yep. Check where you got ‘em from, see if they list any voltages, etc.

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Sunnysunsun
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40*5mw= 200mW. You could just use a >200mW one? Do keep in mind that anything above 5mW will cause blindness.

cgc210
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I’m guessing from some the replies I have received, all of which I am very grateful for , that some do not know that laser diodes are also sold with only a resistor attached AND NO CIRCUITRY. Anyhow I probably should have asked for help with configuring laser diodes that come with just a resistor. It was suggested that I wire the diodes in series until I obtain the brightness level desired. With 50 laser lights this would amount to alot of voltage.
My hope is to find a way to configure the 50 laser diodes most efficiently for brightness and volts/amps HELP

cgc210

Lightbringer
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The really cheapcrap ones meant for “keychain lasers” powered from button-cells do have just a resistor. That’s well specced-out from the characteristics of the button-cells and the additional resistor. Try using it from 3 AA cslls vs 3 teeny little 1.5V button cells and the LD will go pouf fairly quickly.

Same reason a bunch of 5mm LEDs can be crowbarred right across a trio of AAA cells and be only mildly overdriven, but hit it with a regulated 4.5V supply (or even 3 AAs) and they croke pretty much instantly.

The ones I got (like in the pic) are the more common type, and are meant for 5V supplies, ie, regulated. They’re used for robotics projects and the like.

That’s why I suggested going to the listing itself and see what they’re meant for and how they’re meant to be used.

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cgc210
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LB
I really appreciate the time you’ve taken with this. I was under the impression that Amazon sellers were a notch above ebay & AliExpress. Clearly I was mistaken – there not, in fact they’re often the same seller. I have not been able to get anything other than we just sell the product. I’m not new to online buying just laser configurations.
I thought that arraying the diodes first in serial then parallel (because they were already resisted) would give me a fairly even distribution of the volts & amps like an LED array I once put together did. In that arrangement the LEDS were connected first in serial then a resistor was added to each serial line and then the serial lines were connected in parallel. The LD array is not performing like the LEDs did.
Do you have any thoughts or knowledge on doing the same to these LDs that came pre-installed with resistors. Can additional resistance be added to the LDs. Would this even out the brightness among the diodes or cause some other problem. Or, should the pre-installed resistors be stripped from the diodes then configure them as explained above like the LED array, with me adding a resistor on each serial line of the LDs.
Hopefully I haven’t confused things. If you need additional explanation don’t hesitate to ask.

cgc210

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Dunno offhand. Sometimes you just have to play with them.

Or send one to The Big Clive to play with and do a video. LOL

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Photon Master
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Sunnysunsun wrote:
40*5mw= 200mW. You could just use a >200mW one? Do keep in mind that anything above 5mW will cause blindness.

Yes please be careful. I wear wraparound red laser goggles even when I’m putting batteries in a green or blue laser. Even accidentally passing your hand through the beam is extremely unpleasant

cgc210
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Sunnysunsun
Thank you for the advice. Even when the info is or should be known a well intended reminder is ALWAYS helpful. I picked up a pair of red laser protective glasses, but don’t always use them, your reminder has made me more mindful of using them.

The laser diodes are arranged so that a wide area is exposed. One 200mw diode would not give the broad exposure needed.

I’m still tinkering with the volts/amps – trying to get uniform and max brilliance without destroying any. I welcome any & all help. I’ve configured them in series & parallel and series/parallel also. Using rechargeable batteries requires too many batteries to obtain the voltage required. In parallel I can get the uniformity but not the higher brilliance.

A particular issue I’m having with the parallel array is the LDs I’m using have pre-installed resistors. While I understand what a 330 SMD resistor does, I think additional resistance may be required to even out the additional current needed to increase and even out the brilliance of the diodes. I think this is the problem with the serial/parallel array also. The cheap LDs online do not come with info, nor can I find a source of info that talks about additional current and/or just how much more current can be supplied. I don’t have the knowledge to achieve this.I’ll probably return to a serial/parallel array & play with the amps until I, hopefully, achieve the desired results.

With the serial configuration I will have to go with an adjustable AC/DC and just crank the voltage up until the LDs get bright enough. I apologize for the volume of info, my hope is that you or another BLF member may be able to offer input.

Thanks again, very much cgc210

cgc210

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What would be really amazing is if you could combine a bunch of high powered blue beams and shine them through a frequency doubling crystal to make a powerful green beam.

I have a 1 watt green laser and although it doesn’t burn like a blue, the beam looks absolutely spectacular