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can i replace Nichia NDB7A75 with a Sharp GH04C05B9G

GravityRZ

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Hello,

i have a 5v buck driver(4.5amps max) for the NDB7A75, can it also power the GH04C05B9G

i noticed the NDB7A75 uses around 4.3-4.7 volt to operate and the GH04C05B9G needs 4.8-5.6 volts

i figur that the NDB7A75 is probably a bit overdriven bij the driver while the GH04C05B9G stays in a save voltage range

i used to work on flashlights but these laser leds are another ballgame thus the reason i need help

thanks
 



RedCowboy

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GravityRZ

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thanks but my worries are more on the voltage levels i did not measure but does a 5v buck driver give out exactly 5v. i have heared these drivers blow up when there is no load connected so i am a bit reluctant to measure it
 

RedCowboy

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No that's not how it works, the driver limits the current to your max setting of say 4.5A and can output up to 5V if it's needed.
The laser diode will draw the voltage it draws at the current limit.
A nubm44 will draw about 4.5V @ 4.5A, it will never use the full 5V the driver is capable of unless you set the current limit higher.

I just checked my Sharp GH04C05B9G and it draws 4.8V @ 4.0A which is really pushing it, you are better off to stay @ 3.5A and it draws 4.7V
If you try to drive it @ 4.5A you will kill it.....well I killed one and another does the same @ 3.5A so these really look like 3.5A is where we want to be.
 
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GravityRZ

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ok. clear. so if i use a driver which can do 4.5 amps it will probably try to get that (and fry the diode)
this is the driver i am talking about

i need to buy my stuff from china since all the stuff from the usa has very high shipping rates

can not post a link to aliexpress but if you search for 3.5W NDB7A75 high-power blue light drive circuit then you see it.
is it any good?
 

RedCowboy

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I don't know what driver from China that you are talking about however I bought some of these from China and they work well, also they are only 4 dollars which is really nice, they are 3 mode ( 1A ) ( 3.5A ) and ( 3.5A flashing )


 

GravityRZ

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thanks. those look like the sames ones but a lot cheaper. amazinly that i searched ebay but did not find those. thanks again for the help
 

Alaskan

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Robert, I went to ebay and looked at that driver, but I'm not sure what the maximum input voltage is to the driver, do you have that info? Are these hard wired to the current? No way to change?
 
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GravityRZ

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according to the info it needs at least 2x 18650 to operate (5.8-12 volts input) they also advice not to use 3x 18650 because the driver can get out of control if one of the 18650's has a high resistance

for portable usage i better go with 2x 18650's protected
 

RedCowboy

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It says input is 5.8V - 12V ......no there is no pot to adjust.

The strobe function is cool and the 1.0A ( low ) function is fast pulsed where you don't notice unless you move the beam around like making circles/shapes on a wall then you will see the dashes, it's actually pretty cool. On high it's a solid 3.5A steady on so non pulsed in high mode, you can tell it has a ramp up, maybe a 1/10 of a second which is good, these were no doubt made for laser diodes and if you solder to the diode you can use the case pin for your Vin.......it also brags about the reverse polatity protecting being robust.
 
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Alaskan

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I saw the voltage range but unless they say "input voltage 5.8 to 12 VDC" I feel like I need more clarity, they used the word outputs, which was weird to me. Maybe I know too much, the driver will have voltage drop or loss so the output voltage must be lower than the input voltage, thus the specification is wanky. If this driver can output 12 VDC, I would expect a maximum input voltage to be between 13 and 14 volts, but they don't tell us, so what is the minimum input voltage to produce the constant current required for the diode to produce full output power? Without knowing the drivers dropout voltage, I cannot know ahead of time.

I am interested in the pulse mode, I'd like to push the limits of a diode in pulse mode, but then also need current adjustment. Would be nice to also have a way to adjust the pulse repetition rate as well as pulse width.
 
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RedCowboy

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They output up to 5V as needed to maintain 3.5A on high, that's the current limit 3.5A, what they are saying is the input can range from 5.8 to 12v so dropout is 5.8v as far as your batteries are concerned.......for 4 dollars I bought half a dozen and I have one driving a 7A75 build, I like it.


You can use a driver and a cheap digital PWM will let you set cyclic and pulse width, if you set cyclic rate at 20K and PW @ 10% then you will get 20,000 cycles a second with the laser on for 10% and off for 90% of each cycle, your driver will still limit the current.......the PWM itself I listed will output 5-30ma so you can connect it to a small speaker and hear the frequency change as you adjust your cycles and the volume will go up and down with your pulse width as far as what we hear....your driver will have a response range for the PWM but the SXD is only 1kHz and ACS5500 says low rate so try a Chinese driver or make your own.


The driver below is good at 20KHz

If you are going to try and push past max CW current you will need a short PW.



 
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Alaskan

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I bought 12 too :) but from another seller, the link you provided indicates out of stock, for now. Maybe they just need to update the listing. I found them even cheaper from another seller.

Yep, I need a lot of control to pulse a diode higher than normal CW current, and adjustments for both pulse width and repetition rate. Have you seen a driver like that which can be run off of Li-ion batteries?
 
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Alaskan

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Aha, cheap, simple. Thanks!
 

Lifetime17

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No that's not how it works, the driver limits the current to your max setting of say 4.5A and can output up to 5V if it's needed.
The laser diode will draw the voltage it draws at the current limit.
A nubm44 will draw about 4.5V @ 4.5A, it will never use the full 5V the driver is capable of unless you set the current limit higher.

I just checked my Sharp GH04C05B9G and it draws 4.8V @ 4.0A which is really pushing it, you are better off to stay @ 3.5A and it draws 4.7V
If you try to drive it @ 4.5A you will kill it.....well I killed one and another does the same @ 3.5A so these really look like 3.5A is where we want to be.
Hi,
Red is correct thats way to much amps for the sharp405nm diode. That diode is comfortable at 1.6/1.8 tops. I built a few of these in host for customers.
Rich:)

081FC60F-A476-458D-8B18-0DA17EE61870_1_201_a.jpeg
 

RedCowboy

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Hey Rich, he was talking about the sharp 5W which actually runs at 3.5A and has divergence like a nubm44 with a G2
I bought some for 35.00 and tested them, I prefer the 7A75 but I am glad to see other companies making these.

 




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