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Sharp 473nm 55mW Laser Build

CynicalBrad

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USPS has really been messing up pretty pretty badly lately. I understand they have budgetary issues but misdelivering packages and routing them way out to the middle of nowhere does not help that. Had a package recently that came from two states away make a nice 2000 mile detour to Ohio and back. I guess I am lucky that my local office will actually try to deliver bulky packages. My old post office would fill out the dreaded pink forms before they started their route in the morning until our neighbors collaborated to get a few people replaced. They ran a moderate business from home and a missed delivery meant very upset customers when deadlines couldn't be met. And I agree with dtr on their insurance being costly. I personally feel that when they accept the package, it should put them under contract to safely and finally deliver it seeing as they were paid to do so. They should also be held responsible for lost packages seeing as they are the ones responsible for losing them in the first place.
 

paul1598419

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The good news is that my driver showed up in my tracking updates after I reported it to the toll free number. I got it and finished my build. YEAY! These 473nm diodes have such a high Vf that to keep it regulating at 275 mA it pulls ~1.1 amps from a fully charged Li-ion battery. As the voltage drops, it pulls even more current.
 

paul1598419

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Be careful of your run times. That Nano Boost driver runs very hot with this diode set to 275 mA. I'd hate to see you lose it.
 
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CynicalBrad

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Just how high is the Vf on these? +8.0v? I might need to check my build's current draw considering I am using ni-mh aaa cells.. I know I am getting 75mW after lens losses with a 3 element lens but it would not surprise me if my cells can't carry the load that well. Part of why I set mine to 200mA, my green build that I gutted for this was set at 300mA and would drop in output after 5 minutes of use. Nothing bad but a near 20% drop.
 

DTR

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Be careful of your run times. That Nano Boost driver runs very hot with this diode set to 275 mA. I'd hate to see you lose it.
I have not run one for more than a minute but just to note the nano does have thermal protection so the driver will not take any damage it will just shut off to cool down if it gets too hot. Pulling over 1A at the start of a battery charge cycle the efficiency numbers show a drop of around 1.9W as waste heat. Take the SXD for example it drops around 3.5W when running a M140 set to 1.8A and can run continuously. Those are fresh battery numbers and both do get higher as the batteries run through their charge cycle.

I don't remember the exact temp Lazeerer said the components can safely do before damage but it was very hot. The weakest link is the max temp of the solder paste to keep it from softening up and the thermal protection is set to keep from getting even close to that. The driver can sustain a continuous tem that is higher than would be comfortable to touch without issue.

Anyway just want to point out the drivers thermal protection will keep the driver from being damaged and if he said it ran three minutes without the thermal protection going off we know it can at least run that long.

The temp of the diode should be the main consideration in determining the duty cycle you want to keep your build as it is configured. The driver just might impose a duty cycle that is lower than the max of the diode.:beer:
 

astralist

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@Paul:
Assuming the Vf = 7V @275mA and freshly charged li ion = 4.2V
Total efficiency = 0.275 x 7 / (4.2 x 1.1)
Total efficiency = 41.67%

Unless my calculation was wrong, that is some inefficient driver you are using! :can:


@DTR and others:
The usual silicon thermal protection (thermal shutdown) in power management IC like this goes off at 130~165°C with about 20~40°C thermal hysteresis (meaning the driver will continue to work if it cooled for 20-40°C)

Those value are depends on the manufacturer and model number,
for example an SXD driver has a 165°C thermal shutdown with 35° hysteresis according to the datasheet of the IC,
Which is pretty high compared to the other IC which usually at 150°C only
 
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DTR

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I don't have a 473nm right now to check but have a BDR-209 with nano that is set to 520mA. @ 4.2V it is pulling 1030mA. Out is 520mA and forward is around 6.2V there.
4.2V x 1.05A=4.32W
6.2V x 0.520A=3.22W
3.22W/4.32W= 0.745

74% efficiency.

I will have to check when I get another 473nm built to see if it changes a lot with that diode due to the higher forward.
 

astralist

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It is actually makes sense if there is a big efficiency drop since 7V maybe an edge of its boosting capability.
Also, high temperature usually lowering the efficiency as well,
so even if it's jaw dropping ~40% it's quite normal in this case.
 

paul1598419

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Yes, at 275 mA Vf measured 7.1 VDC. It concerned me as I noticed the driver was drawing what I thought was a lot of current to maintain that regulation: 1.1 amps. It works but the Vf on this diode is very high. It hadn't concerned me at all until I got mine built and started noticing this. I'm glad to hear that the driver has thermal shutdown as this should protect it from damage. I wasn't sure about that when I posted, so I just reported what I found.
 
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DTR

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Built a 505nm today with the nano which that diode has about 0.3V lower voltage drop than the 473nm diode @ 275mA on the ones tested . With 4.2V it was drawing 520mA from the power supply.

4.2V x 520mA = 2.18W

6.6V x 275mA = 1.82W

1.82W / 2.18W = 83% Efficiency
 

paul1598419

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I don't remember what the Vf for that particular version of these 505nm diodes were. I can tell you for certain that the Vf for the 477nm diode I used was 7.1 VDC at 275 mA. As I recall there are three versions of the 505nm diode and two have different pin out diagrams. One is case positive and the other is case neutral. I spent the better part of a day measuring everything about this 477nm build I made so I could explain in detail what I was seeing.
 

paul1598419

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Might get them by Wednesday or Thursday. I plan on dropping everything to measure these first.
 




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