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NJG-18, multimode boost driver for 445nm.. and possibly 650nm

SHIN

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Re: 3 mode driver for 445nm, one Li-ion

Hi. qumefox.

You are right.

I think this driver is not advisable for the starter but trial-and-error or challenge is also needed to DIYer.;)
Although this driver is a success-story, but I have much more fail-stories.

SHIN
 



Fivos

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Re: 3 mode driver for 445nm, one Li-ion

Fuck fuck holy fuck this driver explode in my face. I almost killed my self!!! My house also almost caugth fire!!! Fucking driver. I don't know what i did wrong i made the connections as you told me and when i powered it for long hour,, bam!!!! A huge cracking sound like exploding mini dynamite. Wtf, how that happened???
 

Fivos

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Re: 3 mode driver for 445nm, one Li-ion

I found the inductor some inches away!!!
 

qumefox

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Re: 3 mode driver for 445nm, one Li-ion

My guess you had something shorted that shouldn't have been. Though to be honest, I find your story a little hard to believe. I've been in the electronics repair business for over a decade now. There is VERY little on one of these drivers that will really 'blow up'. The only possible culprit I can spot is the 100uf 6v SMD cap by the inductor. Did you have the polarity backwards? Were you trying to drive a load that was wanting more than 6v?

You also might want to consider toning down your language just a wee bit.
 

Fivos

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Re: 3 mode driver for 445nm, one Li-ion

You know this thing almost leave me a scar in the face.It explode close to me.. I had my school books close and they almost caught fire..The driver had been still powered because I run out of the room.I threw a box to disconnect the wires..It exploded I don't know what you say..I took a picture the dead driver though. Sorry for the quality my camera was focused in infinity...And sorry I was so nervous,, I was too shocked....Here is the picture..
<script src='http://img181.imageshack.us/shareable/?i=07112010196.jpg&p=tl' type='text/javascript'></script><noscript></noscript>
 

qumefox

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Re: 3 mode driver for 445nm, one Li-ion

All I can see is a huge blurry pic. Resize to 800x600 and try again. heh
 

SHIN

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Re: 3 mode driver for 445nm, one Li-ion

Good news!

I built another one with this 3-mode driver yesterday.
The power at high mode showed max. 1880mW and then was stable at 1700-1750.
This time I used a small heatsink for 5-pin chip that seemed like flexdrive's.

And I built A140 with 2-parallel flexdrives at 1807mA and the power was 1970mW.
The power was stable after 3-4 sec. at about 1850mW.

SHIN

edit] I forgot one thing.
This 2nd 3-mode and the parallel v5 are both with 445-G-2 lens.
 
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Xtrm2Rick

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Re: 3 mode driver for 445nm, one Li-ion

Good news!

I built another one with this 3-mode driver yesterday.
The power at high mode showed max. 1880mW and then was stable at 1700-1750.
This time I used a small heatsink for 5-pin chip that seemed like flexdrive's.

And I built A140 with 2-parallel flexdrives at 1807mA and the power was 1970mW.
The power was stable after 3-4 sec. at about 1850mW.

SHIN
Sounds really promising, i just might have to order a few more A140's and some of these drivers to test it :D always fun to test drivers.

just wish my package with all my flashlights will arrive finaly so i can make heatsinks for them and put some lasers in them D:
 

ReNNo

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Re: 3 mode driver for 445nm, one Li-ion

I finished my first 445nm build that uses this cheap driver. (DX version that includes strobe modes)

Current settings are: low-23mA (visible beam), med-220mA, high-1000mA.
Laser is stable but I'm worried about input current.

Battery voltage is about 3.9V and input currents are:
low-200mA, med-1150mA, high- 3400mA.

Isn't it too much?
I'll try to recharge battery and measure input currents again.
 

SHIN

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Re: 3 mode driver for 445nm, one Li-ion

Congratulation on your 1st 445nm, Renno.
Do you have a LPM?

My 2nd 3-mode one(5-pin chip heatsinked) shows:
100mW-400mW-1750mW(max. 1880mW)
The current at Li-ion battery is:
140mA-620mA-3200mA

My parallel v5(1807mA at LD) drains:
4.1 - 4.2A

I think this 3-mode driver is worthy of DIY.

SHIN
 

ReNNo

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Re: 3 mode driver for 445nm, one Li-ion

Problem solved.
Internal resistance of DMM that I used was high and voltage drop on DMM was about 1.5V that resulted low voltage on driver (under 2.5V).

I recharged batteries and now I'm using another DMM that makes 0.5V voltage drop and current is about 1550mA for high mode. Without DMM current must be noticeably lower than 1.5A.
This driver looks like very efficient driver for its price.
Only thing that worried me was "voltage spikes". And I solved this problem by soldering one tantal cap (330uF) and two SMD caps (3.3 and 10uF) directly on diode. Now I can turn on laser without fear :)

And one question.
How can I accurately measure input current?

EDIT:
@SHIN
Thanks, I'll post review soon.
No, I don't have LPM and I really want to see 1000mW+ output power on LPM :)

EDIT2:
Another DMM that has lower internal resistance seems like defective.
Sometimes it shows 1.5A input current and sometimes shows 2A.
Input current of 1.5A looks too good to be true, It's most likely 2A.
But even if it's 2A there is 0.5V voltage drop on DMM. Without DMM current must be lower than 2A. And it sound good for its price.
I'm still looking for accurate method to measure input current..
 

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qumefox

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Re: 3 mode driver for 445nm, one Li-ion

You can measure battery draw current the same way as you measure the current draw of the diode. With a 1 ohm resistor in series and measure across it with a voltmeter
 

ReNNo

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Re: 3 mode driver for 445nm, one Li-ion

Sure I tried that but voltage drop on 1ohm resistor is too big and driver gets low voltage and current increases.
Imagine if battery is 4.2V and current draw from battery is 1A. 1ohm resistor will make 1V voltage drop and driver gets only 3.2V. Boost driver always works that way to maintain same output voltage and current. When input voltage is lower then boost driver consumes more current "to generate" constant voltage on output.

I tried with 0.33ohm resistor but even this resistance make about 0.7V voltage drop and current increases.
 

qumefox

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Re: 3 mode driver for 445nm, one Li-ion

Your options are limited then without an adjustable power supply because there are really only two ways to measure current draw. With a shunt (measuring the voltage drop across a series resistor) or via inductive means.. which doesn't work very well for low voltage low current applications like we have here.

My suggestion is to either get an adjustable power supply that shows you current draw to run the driver off of, or use one and set the input voltage high enough that the voltage after the shunt is where you want it.. which is what the current readout on the power supply is doing anyway.
 

ReNNo

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Re: 3 mode driver for 445nm, one Li-ion

I don't have access to professional voltage adjustable supply, can I use LM317 to adjust input voltage?
 

Pontiacg5

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Re: 3 mode driver for 445nm, one Li-ion

I believe an LM317 is only good for around an amp and a half or so, I'm not sure if that's enough for what your trying to do.

An LM138 is good for 5 amps though, and I believe it works the exact same way as an LM317. Google has plenty of variable voltage LM317 based power supplies schematics.
 




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