New - "A better 1W budget boost driver" - AK-007

[rhd]

I'm no believer of the philosophy the LED drivers are kryptonite to our precious LDs. We've heard the mantra that "LEDs can take a lot more abuse" - true indeed - but irrelevant to an extent. A truck can take a lot more abuse than a two-door convertible, but that doesn't mean the gas they run on is any less refined.

We've had some fun with the NJG-18, but it has an annoying quality - it's shape. It's not a huge driver, but it's circular, and doesn't fit the Rayfoss/OdicForce DIY housings. At the same time, I hate hate hate the $15 "1W 445 drivers" that are sold all over ebay, olike, etc - they never hit 1W, and, well, they're $15+.

So after ordering every LED driver that even looked remotely capable of use for our 445s, I present the AK-007.
$3.10 - AK-007 0.8~1.5V 3-Mode Circuit Board for Flashlights (11.9mm) - Flashlight Parts and Tools

It's about $3 from DealExtreme, and is absolutely tiny. In fact, it's just under 12mm, which makes it the tiniest bit smaller than an aixiz module. In fact, you could probably almost hide it inside an aixiz entirely.

Before I go any further, I should also mention that what you can't see in these photos, is a 10uF ceramic cap protecting the diode. Here's my "module" built. The copper wrap is just to expand the width ever so slightly for a snug fit in the host:

Here it is before insertion, minus lens:

And after insertion:

The neat part? It's a very consistent driver from my testing thus far. Using 1x 16340 Lithium Ion, I'm getting a peak of just over 1,000mW output.

It also seems to work well for 405nm 12x diodes:

Compared to the $15 boost drivers for 445 that in reality achieve <900mW, this is a no-brainer.
No pot for controlling current, but for a driver with such a small footprint, I wouldn't expect it.

 

[Mohrenberg]

This is great!

I bought 10 of them for $24.81 shipped!

 

[rhd]

Also - modes are bypassed if you just take the negative feed directly instead of from the driver.

 

[Bionic-Badger]

Pretty interesting how it maintains nearly exactly 1W of output, which would require boosting to 4.5V and ~900mA, for a driver that is made for 0.8-1.5V input and LEDs that only need 3V and 300mA. I wonder what the long-term performance is and what it's scaling curves really are?

 

[rhd]

The way I designed that module build, the entire IC is basically arctic silvered to the aixiz module. Like any new driver, we need feedback from more than one person. But so far, it's working well on my end.

 

[Johnyz]

Being a driver designer myself, the only thing I can say now is: GOSH DARN DX RUINING ME BEFORE I EVEN START!

 

[rhd]

Updated OP with 12x diode LPM - seems to work well for 405s too:

 

[JaiNobeZ]

Sorry if i'm stating the obvious, but this looks like a pulsed driver. In which case the average power is a lot lower... or am i missing something?

Also, what are the modes?

 

[scopeguy20]

Now I'm really interested, is it pulsed and if so, XHz?

 

[rhd]

Nope, it's not pulsed.

It has one mode that is a 9 hz "pulse", but I would hardly consider that a pulsed driver for our purposes here. It's a slow enough pulse that you can see it without and movement of the laser. Basically, it's the pulse you would expect from any LED flashlight driver. And that's only on ONE mode (there are three, High-Low-Pulse)

Having said that, the pulse is a lot smoother than the pulse on the NJG-18. IE, it doesn't appear as "broken". In fact, it would surprise me if the 10uF cap is responsible for basically smoothing out the pulse mode. Having said that, I've used caps on all my NJG-18 builds, yet they have a very distinctly sharp on/off in pulse mode.

Again though, the modes are optional.

 

[JaiNobeZ]

Oh right. I only just began to understand the power readings. ...This hobby makes me feel stupid sometimes... haha

In which case, why does it have that ramping up time? Am i correct in my understanding that it's taking 50 seconds to reach maximum power? And isn't there a clear problem with that in a host this small?

Or, once again, am i horribly misinterpretting?

Also, i love the idea of a driver with a pulse mode. Been wanting a pulsed laser for a while. If all comes out favourable, i may use this in a build sometime.

 

[anselm]

Holy crap, this is a great find!!
Would you be able to measure the current it draws from the single LiIon, pretty please?

why does it have that ramping up time?

Imma take a wild guess and say that power "development" is the LPM gettings its act together,
not the driver...

 

[rhd]

Imma take a wild guess and say that power "development" is the LPM gettings its act together,
not the driver...

I'm not entirely sure whether it's the LPM circuitry getting "going" or just the thermopile heating up. I assume that latter.

 

[3zuli]

cool. did you measure the output current? is there any pot?
I'll order few pcs and test them with my o-scope

 

[JaiNobeZ]

Ok, so the curve is not a property of the driver? Sounding good so far. Does it need heatsinking? And what's the Ampage on the low-power mode? (Tell me if these are stupid questions)

Slightly off-topic. Do you find the Rayfoss torch hosts always have really smudgey output windows?

 

[123splat]

Rhd,
Where did you put the 10 mike ceramic, on the driver, on the LD pins, or what (I'm assumming that it was a SMD). Did you replace the LED leads, or use what came on the driver? I plan to use one in a Guidesman host with a seperate heatsink for the driver. So, new leads for the LD and... hot from the guidesman sw to driver and Black (neg) from the case pin on the LD to the outter ring on the big board of the driver (to still have modes), or to the black LED lead connection (to bypass modes??)?
Sorry to bombard you with such stupid, elementery, questions, but, I ordered three from DX and I figure that it'll take say an eon or two to get them and the this thread will have gone off and left me before i get the drivers... So, I'm trying to ask everything that I can think of while the thread is still hot. Thanks,
Splat