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How do I turn a lazer diod on/off quickly?

LaserLearner

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Dec 5, 2023
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Hello, I am new to this so be patient. Several years ago I assembled a simple red lazer (5v, 650nm) array to aid in healing sore muscles and joints etc. It works great. Wanted something a little more powerful to penetrate deeper into tissue so I purchased similar 980nm diodes and a $6 pulse generator with the idea that I would limit any heat buildup etc. when using the lazer. I hooked them together and the diode is defineatley pulsing but the intensity is very low. The pulse generator has both TTL and Pwr/Gnd connection points. My diodes are not TTL as up until this now I only needed to understand + /-. Would a TTL diode connected to the TTL connection on the pulse generator solve the problem? Any suggestions?

Thanks.
 





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Aug 31, 2016
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Hello, I am new to this so be patient. Several years ago I assembled a simple red lazer (5v, 650nm) array to aid in healing sore muscles and joints etc. It works great. Wanted something a little more powerful to penetrate deeper into tissue so I purchased similar 980nm diodes and a $6 pulse generator with the idea that I would limit any heat buildup etc. when using the lazer. I hooked them together and the diode is defineatley pulsing but the intensity is very low. The pulse generator has both TTL and Pwr/Gnd connection points. My diodes are not TTL as up until this now I only needed to understand + /-. Would a TTL diode connected to the TTL connection on the pulse generator solve the problem? Any suggestions?

Thanks.
You need a constant current driver with PWM/TTL input to run the diode. What current are the diodes rated for? What frequency are you trying to pulse them at?
 
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You say it's working so I assume you have a driver with TTL imputs between your laser diode array and your pulse generator, so Increase the pulse width on your generator.
 
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You say it's working so I assume you have a driver with TTL imputs between your laser diode array and your pulse generator, so Increase the pulse width on your generator.
It sounded to me like he hooked the diode right to the PWM generator. The 3.3v or 5v output would probably run a diode just not with any real power.
 

LaserLearner

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Thanks for the quick response. Here is what I am working with:

5pcs Focusable 980nm 30mW IR Dot Laser Diode Module

Parameters:

Size:12x35mm
Wavelength:980nm
Output Power: 30mW
Working Voltage: 3-5V
Focusable: Yes
Laser shape: Dot (Rectangle to Oval)

1701804497089.jpeg

1701806342521.jpeg

And I am using an old 5v cell phone charger for a power supply. Not sure what the frequency or duty cycle would be right now - was going to build it an test for heat etc.
 
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So your 980nm lasers are going to run continuously and you were only using the PWM to limit heat, if so why not put them is small aluminum finned sinks ( which they really don't need @ 30mw ) and you can use a wall wart supply and lm317 linears to drive the lasers to 30mw which won't make much waste heat.



Or you could use these with the drivers built in.


Or you could use the lasers you have and these drivers, you will only need like 80ma to get 30mw and these are adjustable up to 600ma..... however I wouldn't run them all in parallel off 1 driver, use a driver for each and power with your 5V supply.

 
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LaserLearner

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I wanted the laser to pulse to control heat buildup in my joints as the laser dissipates energy. Not sure if these generate enough heat to be a concern, but if it was easy, it seemed like a reasonable precaution. The laser powers up fine connected directly to the power supply. When connected to the PWM they do pulse, but w very low intensity. If I purchased the lasers with TTL drivers will they work better with the pulse generator? Will the ones I have work connected at PWM if I use a larger power supply?

Thanks.
 
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This pic matches yours and the description matches. Is this what you bought ?


The way they say 3-5V input makes me think these laser modules have basic driver boards inside.
You need drivers that will take a TTL input to use your PWM

You can unscrew the back half and take a pic of what's inside, then post it here.

Really you could just connect your 5V to the lasers, they don't output very much anyway.

Yes the other laser modules with the 3rd wire will take your PWM signal.
Laser module Red wire is positive and black is negative as well as your PWM negative ( both negatives connect to the black wire ) then connect your PWM positive ( output ) to the laser module yellow wire.

Set your PWM between 1-15000 so maybe 5000 or 10000 and then you simply adjust the pulse width expressed as a % to control how long its on and off during each cycle.
 
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kecked

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There isn’t enough power to create a heat problem. Pulsing them isn’t going to increase the peak power so if you desire more juice you need more diodes or bigger diodes. You need to calculate the amount of energy absorbed which is very complex in living tissue. Since this is IR also be careful of reflections. It you hit something reflective you can with that level of power harm your eyes. I have no idea how or why this works so I’m just speaking about the lasers. I do agree if you are worried about heat I. The lasers the self get metal heat sinks.
 

LaserLearner

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It looks like I could replace the simple drivers with these and convert the diodes I have to TTL:

ebay: 635nm 650nm 808nm 980nm TTL Laser Diode Driver Board 5V Supply Supply 50-300mA​


1701882364591.jpeg


(I'm not allowed to post links until I have more activity on forum)

Slightly cheaper than new diodes (but more labor intensive:)). Would these work? I intend to use 3 in an array, is the 5v phone charger enough power?

Thanks.
 
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Probably, what's the output on the 5V charger, should be printed on it.
 




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