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

qumefox

qumefox

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Re: NJG-18, multimode boost driver for 445nm

Bet that gets hot quick. I don't know. I think i'm probably the only one, but I don't really like high power builds in tiny hosts.. Duty cycle is just too crappy, and if it accidentally gets turned on in your pocket or something, it could kill itself before you ever even realize it was on, especially if its in something insulated like a coat pocket. Also, bet the battery life is pretty short at those currents too. heh.

But that aside, it does look pretty. :D I have one of those flashlights floating around somewhere as well, though mine's an old style twist on. It doesn't have a clicky.
 





A

anselm

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Re: NJG-18, multimode boost driver for 445nm

So lemme get this straight: These drivers are capable of powering a 445nm diode
off one single Li-Ion cell (4.5V output from 3~4V input)?
They can actually boost the voltage (a bit)?

Awfully nice little laser there, DTR! As always :gj:
 
rhd

rhd

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Re: NJG-18, multimode boost driver for 445nm

I think I am doing something massively wrong, or perhaps missing a step here. I ordered from the American source listed mid-way in this thread.

- My board came with the capacitor already bridged (the "fix")
- I disabled the "modes" by bridging the negative and that particular leg of the IC
- For what its worth though, my continuity test on my meter already seemed to think they were bridged.

Anyway, I can't get over 320mA with a single 18650 li-ion. Doesn't seem to matter what brand.

I've tried a couple test-loads. 4 diodes, 5 diodes, 3 diodes - that doesn't seem to matter.

Am I missing something simple here? Or did I somehow miss a "mod" step somewhere along the line in this thread?
 
DTR

DTR

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Re: NJG-18, multimode boost driver for 445nm

rhd said:
I think I am doing something massively wrong, or perhaps missing a step here. I ordered from the American source listed mid-way in this thread.

- My board came with the capacitor already bridged (the "fix")
- I disabled the "modes" by bridging the negative and that particular leg of the IC
- For what its worth though, my continuity test on my meter already seemed to think they were bridged.

Anyway, I can't get over 320mA with a single 18650 li-ion. Doesn't seem to matter what brand.

I've tried a couple test-loads. 4 diodes, 5 diodes, 3 diodes - that doesn't seem to matter.

Am I missing something simple here? Or did I somehow miss a "mod" step somewhere along the line in this thread?
Click to expand...

I have several set up and running great that did not have the fix soldered and I just added the negative and positive wires in the regular spot. On the ones bought from the US seller they probably had the positive and negative wire already soldered. Then I just hooked the battery and the diode's negative side to the driver negative output. Here is a shot. This set up is the same thing as bridging the case pin and the negative pin on the diode and not running a negative input into the driver. It comes on with no modes and runs full power. I have had no problems setting up this driver this way but have had issues with any of the other ways.:D

p1014926.jpg
 
rhd

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Re: NJG-18, multimode boost driver for 445nm

Hey DTR - thanks for the advice.

I had the whole (-) lead as a continuous source thing figured out, and I'm pretty sure I'm wired up correctly to the driver.

In your shot, is that 1x 18650 powering it?

Also, what's your test load? It looks like just two diodes?
 
DTR

DTR

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Re: NJG-18, multimode boost driver for 445nm

rhd said:
Hey DTR - thanks for the advice.

I had the whole (-) lead as a continuous source thing figured out, and I'm pretty sure I'm wired up correctly to the driver.

In your shot, is that 1x 18650 powering it?

Also, what's your test load? It looks like just two diodes?
Click to expand...

I am power it from my bench supply set to 4.2V to simulate a fully charged single Li-Ion. As for the test load it is from flaminpryo and It has six diodes.:beer:
 
LarryDFW

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

ReNNo said:
And one question.
How can I accurately measure input current?
Click to expand...

This is the Ammeter Shunt I use:
imageMKA_5_150.jpg

You still need a good rms voltmeter to capture the waveform.

LarryDFW
 
LarryDFW

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

ReNNo said:
And one question.
How can I accurately measure input current?
Click to expand...

This is the Ammeter Shunt I use:
imageMKA_5_150.jpg

You still need a good RMS voltmeter to capture the waveform.

LarryDFW
 
rhd

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Re: NJG-18, multimode boost driver for 445nm

Well guys, I don't know what I'm doing wrong :(

Off one li-ion cell, I should see more than 400mA max current right? Serious clarification point here, lol. Because I just tried the second driver, and I'm hitting the same wall.

Were there any resistor mods required? Anything like that? (I didn't see any in the thread)

Cheers
 
rhd

rhd

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Re: NJG-18, multimode boost driver for 445nm

Wow - nobody will ever guess what the issue here was -

An alligator clip wire. For some reason, when I use an alligator clip wire to connect the 18650 to this driver, I get around 500mA max. If I use an alligator clip for just one terminal, then around 750mA. And if I use regular wire, 1000mA as expected.

I don't understand this - the same wires have no impact if I use them between the driver's output and my meter. But for some reason, when used on the battery side, they impact the driver's output. Odd.
 
BShanahan14rulz

BShanahan14rulz

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Re: NJG-18, multimode boost driver for 445nm

battery has to supply a lot of current. Higher currents don't like wimpy wires.
 
DTR

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Re: NJG-18, multimode boost driver for 445nm

^^^^^This driver pulls almost 3A to put out 1.4A.:)
 
A

anselm

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Re: NJG-18, multimode boost driver for 445nm

BShanahan14rulz said:
Higher currents don't like wimpy wires.
Click to expand...
Neither do they like crocodile's teeth.:D
They love soldered connections though!

The current is higher on the battery side, due to the driver needing to boost voltage.
But 3A for that little bit of boosting?
Sounds like a terribly inefficient design!
 
Last edited:
rhd

rhd

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Re: NJG-18, multimode boost driver for 445nm

These are hefty alligator wires. Like 3 to 4 x the thickness of Flaminpyro wire.

An interesting note though (related note) - I was testing the resistance values, and they were 0.7 ohm. That's pretty substantial (I think). You certainly wouldn't want to string together the reference resistors while tinkering with a DDL driver, with alligator wires.
 
BShanahan14rulz

BShanahan14rulz

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Re: NJG-18, multimode boost driver for 445nm

anselm has a point too. Physically speaking, the contact between the aligator clips and a wire will be less area than the area of the cross-section of the wire by quite a bit. This is one of the bottlenecks that causes resistance.

If it does pull 3A, you people should stick to 18650 cells.
 
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