Hi first post on this site so be gentle with me

I am using a Duo with a 14 Led array and one of Biffs single focus Led's

Having read thru various sites including this one I figure you could replace the array with a single Cree, the question is can you?

1/ Can you run a Cree of a standard Duo battery pack (4* AA)?

2/ Which Cree do I use R,P,Q....3,4,5?

3/ Do I need a heat sink?

As you can see new to this please help

Michiel

(I'm assuming you were planning on making a replacement for the 14-LED unit, not trying to modify that unit with a Cree instead of the 5mm LEDs..)

You seem to be asking some pretty good questions for someone new to this.

1) You can't run a Cree directly from 4xAA

You could connect it with a resistor in series (which would waste a fair fraction of the energy, and give you one power level).

You could use a simple switching 'buck' converter with a single power setting (buck converters convert from higher to lower voltages, generally at decent efficiency).

You could use a more advanced buck converter with multiple power settings.

It really depends how much you're looking at spending, and how flexible you want the result to be.

2/ In practice, there don't seem to be many R2s around even now. Since Q5s (about the most efficient available) aren't significantly more expensive than P4s (about the least efficient available), it probably makes sense to go for a Q5 even in the practical difference in efficiency/brightness isn't huge.
Personally, I tend towards Seouls myself. Though maybe fractionally less efficient than the best Crees, they do seem to be consistently a more mainstream white compared to many of the Crees (or at least, compared to many of the Crees available to buy as bare diodes)

3/ A lot depends on the power level(s) you're thinking of running at. If you were running around a Watt, you could probably get away with a few square inches of thin aluminium sheet, which might well be feasible in the space available.

What voltage do you need? You could reconfigure the cells you have in the box to get something closer to the desired voltage, which might save the need for a controller.

Mark

It's not so much a question of voltage as of current.

LEDs are highly sensitive to slight changes in voltage, and those sensitivities are different between LEDs of the same type, between the same LED cold and warm, and between the same LED new and used.
That means that realistically, LEDs should be used with either a current-regulating controller, or at the very least, a series resistor.

It is possible to direct-drive LEDs in certain circumstances, but of those I can think of, I'm not sure (m)any of those circumstances would apply in this case.

Practically speaking, simple controllers aren't expensive.
For example, though it would need a small component changing to select the drive current, there is a single-level buck converter
http://www.kaidomain.com/ProductDetails.aspx?ProductId=1640
available for only a few dollars.
In fact, it would need the component changing anyway, since as sold, it's set up for a current a little too high for it to be reliable (1Amp rather than the claimed 750mA).

I run both a cree q5 and an ssc p4 in my duo with great success, check the "inside the duo" post. these guys are a good source of parts- http://www.dealextreme.com/products.dx/category.917

The main problem with dealextreme (and kaidomain) is that they can be a bit thin on information.

There are loads of drivers on the sites (maybe even too much choice), but often little information on real specs, efficiency, etc.

Well thanks to all your replys and several days on the interweb I think I know what to do now, ish....

Great pics on the Inside a duo thread, did you need to use a buck before the driver Agrophobic or was it the SKU4725 which seems to do both?

I noticed that you have just stripped out the interior, do you think that removing the LED array would give me enough space to fit a Q5 with that driver/buck?

I used the sku10421, no need for a buck when running from 4 AAs in the duo.
Yeah, the site can be a bit thin on info on the drivers but other users posts on there are handy. sku3256 is good too if you dont want the modes.
i stripped out the interior to give me space for new switching and optics, if you are happy to run with the duo switch and no optics then there should be space, not much room for heatsinks though, i eventually replaced my reflector with a heatsink as well as the alluminium plate i mounted the leds on. it still gets hot in the workshop but stays cool underground.
candlepower forums has some good info too.

OK so I got all my bits now, and its time to play.

I plan to mount the Cree and driver on an Aluminium plate that is the same shape as the LED insert and then take the power supply from the 2 pin 'socket' at the back.

Now comes the problem, I have very little idea about electronics and cant figure out which is the input or output on the SKU7425 driver that I have bought 

Can any one out there help

I'm in the process of collecting the components to install a single SSC P4 in a Duo. I'll be interested to see how yours goes as I should be able to start mine in a few weeks. I don't know about the DX drivers and I've heard one or two things about them not being 100% user friendly so I've opted for a bFlex Buck driver. 10 times the cost but looks like it could power some serious LEDs. I'm planning on completly emptying the guts of the Duo and starting from scratch. I'm a little worried bout getting a big enough heat sink in which is why I'm not doing the same as you.
Eventually plan to add another P4/P7 or a bank of 14 high power LEDs to give a low consumption lighting/non retina burning option.
Good luck and keep us all posted.

By the way, check out the www.candlepowerforum.com, a lot of drivers etc get mentioned on there and I think the guy who runs DX is on too.

The input goes to the rings on the back of the board, + to centre, -ve to outer ring.
the output comes from the red and black wires coming off the board. red to + of led and black to -ve. (red wire is common with battery +ve connection.)

Thanks to all with your help with this project
Have had time over xmas to work in the cellar and the results are!!!!
Well would paste them up but cant figure out how, so in words...

Took out the 14 led array and the spare bulbs, wont need them any way

Cut down the small bulb holder to allow the insert, base plate to lie flat,

open up the small bulb to reveal positive and negative in a ready made holder.

Solder on wires to base of driver from bulb base

solder on Cree to attached red and black wires

stick Cree on to base plate

Cut down reflectctor to fit

Reassemble

Notes  I used the array as a template to make the base plate from 4 mill alumininium plate, I hope this is enough to act as a heat sink

I will try to post some pics soon and help others to do the same, light is fantastic! poss too good for the yorkshire scrattling we tend to do!

Have a great new year year

And to you and yours.
Judging by the heatsinking i had to do on mine, which involved two alluminium plates the size of the front glass of the duo and filling with heatsink compound, i think you need more than just one the size of the 14 led pcb. unless you dont run the led at full power.
Mine still reches 80 degrees on the heatsink in the workshop but is much cooler underground. the led will handle 150 degrees absolute maximum but you lose brightness as it gets hotter so you reach a point where you are better running at lower power to get more brightness unless you can get rid of the heat. this was always my main concern with using a duo headset. i'm planning on getting a friendly cnc engineer to machine me an alluminium block with holes to take the optics, leds and drivers.
let us know how you get on anyway.
p.s. yes its too bright for most skye caves too but you can always dim it down.

I got back from my x-mas 500 mile family seeing expedition the other day and found all the components I'd ordered waiting for me on the door step. Brushing the presents aside I began....
I started with an old Duo (twin halogen) and mercilessly stripped out the interior (with help from the 'inside Duo' post). By far the hardest part of the operation was getting rid of all the little plastic lugs and fixings to leave the inside hollow.
I butchered my girlfriend's army mess tin to get the ally I needed. A couple of hours of fileing later and I had a perfectly formed back plate to mount the LED on. On the back of the ally plate I fixed a number of copper coins to suck the heat away. I used a silicone heatproof adheasive for this. I drilled a 5mm hole for the wires to pass through and a 3mm hole for the low battery warning LED.

I glued the main LED (Seoul P4, 3.2v 1000mA, 240lm) into place on the front of the plate and mounted the optics (10.5deg).





The Driver circuit, a bFlex Buck converter, I glued to the back of the plate and wired the various bits together.
The switch was hard. I tried to copy the rod and cam idea but gave up due the complex nature of the build and I wanted a simple solution. Currently I have a standard, small SPST MOM push to make switch resin'd to the inside of the Duo where the original rotator switch came out. Currently not waterproof but I need to add a rubber cap and a bit of silicone sealant.



After a bit of tidying I had to resolder a few conections as I had initially used cheep wire. A quick trip to Maplins later for good wire and I spent most of the morning de-soldering and re-soldering all the wiring.

The Duo's original reflector got chopped to accomodate the optics. Quite a slow job but its now an exact fit and gives a nice dim, wide splash as well as the powerful spot.

Driver from http://www.taskled.com/bflex.html, ?23.52
P4 + Optics from http://www.led-tech.de/en/High-Power-LEDs-Seoul/-3.5W-Seoul-LEDs-c_121_78.html, ?16.98
Wire, red LED and tools from http://www.maplin.co.uk/

Assembled unit


With light on


You can see the low power warning light in this one


I'm currently doing some runtime tests and trying to work out the different trip points for the battery warning lights. I will post the results when I get them along with some photos of it in action somewhere.
All in all I'm quite chuffed with how this went. My soldering needs to improve! The next conversion will be and FX. I love the Duo but its a pain in the arse to fit out with a switch. It took me ten minutes to adapt an FX switch to do the job.
Reliability is my main concern. If it is too complicated or contains too many fabricated components then something is bound to fail. I would like to build something that will be bomb proof, like the original, just better.

Apologies for the naff cushions!

Looking good Pete. i like the warning light idea.
can you tell me what current the driver is drawing from the batteries? this will give you a good idea of run times.
mine draws approx 650ma and gives 5 hours on full brightness from 4 duracell 2650mah.
I know what you mean about keeping it simple to give you reliability. mine is still going strong after several trips underground and a good soaking and bashing so i wont be opening it again unless i really have to.

I've just picked up a multimeter for the first time ever so it may take me a while to figure out what I'm checking as I'm self taught in the last few weeks (any advise welcome). I have 4 different drive levels on the BFlex driver, max being 1000mA which I am currently set on.
I've done things the old fashioned way. Please correct me if I'm wrong but here goes...

LED: 3.8v at 1000mA  V*A= W  3.8*1 = 3.8W

Batteries, 4 NiMH 2650mAh, 4.8v
Driver, 85% efficiency

To deliver 1A the driver needs to draw 1.176A

Batteries: 4.8v*1.176A = 5.64W

At 1.176A batts run for 2.25h      2.25h*5.64W = 12.7Wh

So at full power: 12.7Wh / 3.8W = 3.34h  or  3h 20min

I found a little download program called LED Pro 2.12 and putting the same info in gives me 2h 51min so I'm not sure that is right. I'm sure my mistake is in the efficiency. Have I factored it in correctly?

Runtime test is a bit more conclusive, 1000mA full power:
At 3h 30min light drops to 2nd power setting
At 4h very dim but still useful
At 4h 30min LED goes out

Using the same calc I work out that the light will run for 8h 18min on the next lowest setting, 490mA 3.14v. Currently doing an actual runtime test on this setting, light should die at 11:30 tonight.

I just received the 3 x Seoul P7 LEDs and full current (2.8A) drivers which I bought for a Christmas holidays project. So it will have to be a Winter months project now. Needless to say, I'm not going to try and mount them in a Duo headset. My plan is to build some photography lights. The LEDs are mounted on aluminium disks, but I believe I will need to attach these to a substantial head sink still. Not sure if I can waterproof it and still let the heat escape from the box. Anyone know how waterproof the actual LED modules are if I mount them on a heat sink on the outside of a box?

Heat should radiate from the box sealed or not. The Duo with P4 I have warms up nicely but never gets above a comfotable touch temperature as heat radiates quickly into the atmosphere. I know that 3 P7s will give way more but if your heat sink is big enough it should cope fine. Doubt LEDs will last long in damp environment on outside.