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Thread: Picasso Light

  1. #1
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    ... and if we just ... Picasso Light



    Here is my first ever attempt at building a DIY LED light. After reading all of the back threads from probably the last three years here plus many other associated references, I felt like I had a reasonable idea of the sort of light I wanted to build.

    First of all it had to be simple; I have no machine facilities apart from a drill stand. I also felt like I wanted to keep it reasonably cheap in terms of components – I didn’t want to be buying expensive drivers like the Taskled ones (great as they obviously are) and finding I had made an error in judgement due to my inexperience with designing and building lights.

    I initially ordered one of the MTE SSC P7 flashlights from DealExtreme along with various other associated items such as 18650 Li-ion batteries and a charger, just to get a feel for what might be possible with the modern LEDs. I needed a new flashlight anyway and I figured the batteries would come in useful as well when I decided to build my own light.

    After much deliberation I eventually decided to build the “Easy DIY” light first conceived by Citizen Kane:

    Easy DIY

    The details of the build were well documented by CK, the case was easily available in the UK from Maplins and well, even Troutie had been moved to build one! What better recommendation could you have than that?

    To cut a long story short I posted my initial thoughts on this thread:

    Does This Make Sense?

    With the excellent advice offered there especially from tamen00, I decided upon a 4 XP-G design wired in a 2S2P configuration using the Kaidomain driver known as“kennan” which would give a 500 mA supply current to each LED. This would give me 778 lumens from the 4 XP-Gs which I thought may be on the high side for road work but then again, what the heck! This is one time when more is more isn’t it? Using two 18650 2500 mAh batteries in series would give me a potential runtime I calculated, of around 2 hours 10 minutes before dropping out of regulation – more than enough for my purposes.

    With the immanent release of the new XP-G I felt like the Hammond case was perfect for four XP-Gs in a row with the 10mm optics from Carclo. With delivery times from the other side of the world taking weeks I decided to order 8 XP-Gs from Cutters along with the Carclo 10417 Tight Narrow optics and the driver boards from Kaidomain just in case I wanted to build the Easy DIY version as well.

    I was intending to build the light for road work (heresy, I know) which is why I went for all tight optics. Now that winter was approaching all of my night riding was on narrow, unlit, country roads in the UK (more of which later).

    During the wait I set-to actually designing the whole thing in a CAD package I have and playing about with various options including exploring DIY battery case designs as well. During that process I started to consider different configurations of things including my own case and eventually came up with the cube design which I thought was actually quite cool. Inspired by odtexas’ brilliant bench saw, finning technique, I was also intending to experiment with this also (did I mention I have a bench saw?). Coincidentally I had done some cutting of aluminium angle in the past for something completely unrelated, so had an aluminium saw blade already as well.

    With further experimentation with the designs I eventually came up with the idea using channel section for the body over a base where I could fix the all the components to. This seemed like a good option as it meant I could easily open up the case and get at the components if I wanted to modify or fix them.

    Anyway here are the final details:

    Light Source:

    4 XP-G R5 on 10mm MCPCB wired 2S2P driven at 500 mA yielding a theoretical 778 lumens

    Optics:

    Carclo 10mm XP range 10417 Tight Narrow

    Housing:

    30mm x 3mm aluminium channel section with another piece of same cut down to angle section for base/back plate. 5mm thick slug glued to base with Arctic Alumina thermal adhesive. 2mm Lexan faceplate. I also created a ‘T’ slide for the Cateye mounting bracket which is fixed to the back plate with epoxy adhesive. I haven’t fixed the cover to the baseplate permanently yet as I am still deciding if I want to modify the construction.



    Mounting bracket is a Cateye SP10 Flex Tight bracket which I just happen to have lying around from an old broken rear light. I really like the way this works though because it can be swivelled in both relevant plains to adjust the light direction very easily and fixes to all sizes of handlebar without any rubber shims that most other designs seem to need.



    I tried to achieve a brushed aluminium finish using what we here in the UK call Wet & Dry paper. It didn’t come out too bad for a first attempt which hopefully you can see in the pictures.

    Power Source:

    2 x 18650 (2500 mAh) Trustfire Li-ion cells run in series to give a nominal 7.4V. Connects to light via 12V dc plug and socket on light. I constructed a “Dynamite” style battery holder which works really well and allows me easy access to the batteries for charging in a standard DX charger.



    Regulator:

    Kaidomain “Highly Efficient” driver generally referred to as kennan:
    http://www.kaidomain.com/ProductDeta...ProductId=1640

    Performance:

    I hade my first ride with the light on the road on Tuesday evening. My initial impression was slight disappointment as although the amount of light output was literally a quantum leap from the Hope Vision 1 I had been using, the spread seemed a bit wide with not enough throw for the fast, road riding I was doing. After my usual two hour training ride I returned home and kept the light running to see what the actual total runtime would be. The light started to dim at 2 hours 15 minutes and I kept it running for another 15 minutes before removing the batteries and measuring the voltage at 3.21V and 3.18V.

    Last night I scheduled my first ever off-road night ride and right from the off it was apparent that this was what the light was born for. Plenty of light and more than enough throw for the slower off-road speeds we were riding at. With an accompanying tighter head-mounted light this combination was more than adequate for all but the fastest descents.



    Modifications

    I have noticed that in use the light does not get very warm at all even though the outer casing isn’t fixed yet. It might well be that I was a bit conservative running the LEDs at 500 mA and will probably up this to 700 mA. This will provide a useful boost to 1056 lumens solely for off-road use but this will also reduce the runtime down to about 90 minutes so I might have to up the battery pack a bit maybe to 3 cells which is no problem as this driver can handle up to 18V.

    On reflection I think that box section would give a better overall finish to the light and I have decided that I would have preferred to have the mounting on the bottom of the light rather than the back. This would make the light sit up slightly higher and make tightening the Cateye bracket easier.

    One thing that has happened on a couple of occasions is that the plug from the power lead has caused a bad connection both on and off road, causing the light to go off. The plug has not come out of the socket just come loose. It may well be that the plug and the socket which were sourced from different suppliers may not be an ideal fit. With the proposed shift in mounting bracket that I highlighted above I would probably dispense with the connecting socket altogether, preferring to bring the power cable straight out of the back plate as many builders here do already.

    Conclusion:

    I have been very pleased with the outcome of this light in so many ways. The sheer pleasure of designing and building a light of this power which would shame most of the commercial offerings on the market for a fraction of the cost is something you can’t put a price on. Also the ability to tailor the package to exactly meets your needs is also something very difficult to achieve with commercial lights unless money is no object.

    I will probably make the modifications outlined above and keep this light solely for off-road use. I am already planning a tighter beamed light for my roadie jaunts and also to double as a headlight off-road (yes, I’m hooked). I already have orders for two versions of the Picasso light from my friends as well so I should be busy over the coming weeks!

    I would like to thank everyone who has contributed to making this forum such an interesting and informative place. Not just those who have helped me directly, but I have taken inspiration and encouragement from almost every post here in one way or another.

    Oh yeah, if you hadn’t worked out my pretentious light name by now, here’s an extract from Wikipedia:

    Pablo Diego José Francisco de Paula Juan Nepomuceno María de los Remedios Cipriano de la Santísima Trinidad Ruiz y Picasso (25 October 1881 – 8 April 1973) was a Spanish painter, draughtsman, and sculptor. He is one of the most recognized figures in 20th-century art. He is best known for co-founding the Cubist movement and for the wide variety of styles embodied in his work. Among his most famous works are the proto-Cubist Les Demoiselles d'Avignon (1907) and Guernica (1937), his portrayal of the German bombing of Guernica during the Spanish Civil War.

    Regards,

    OTH

    (with apologies for the length of post and the crap beamshot – no manual setting on my compact camera)
    Attached Thumbnails Attached Thumbnails Picasso Light-pict0167.jpg  

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    Picasso Light-pict0151.jpg  

    Picasso Light-pict0161.jpg  

    Last edited by OverTheHill; 11-06-2009 at 03:09 PM.

  2. #2
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    Very nice and awesome write up! Can't wait to see the next versions!

  3. #3
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    for some reason I cant see any pics :S

  4. #4
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    Don't know what happened there guys, they were there and then they weren't!

    Have uploaded the images again.

    Regards,

    OTH

  5. #5
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    looking good that mate

  6. #6
    lumen junkie
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    Also could be a Borg light...looks good on the bike. I just ordered a bunch of the cateye mounts. They have the spacers in stock now.

  7. #7
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    I like the low and forward mounting position of your light. I have not seen that particular mount before.

    JZ
    It's not about speed, it's about lack of control.

  8. #8
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    The write up is looking good. The Cubist play on name is very cool as well, but Borg would be a good way to go.

    Once you build your first light.
    [SIZE="4"]Resistance is futile................[/SIZE]

  9. #9
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    Thanks for the positive feedback guys.

    Apologies to the board again for the image foul-up, I still don't know what happened. I previewed the post before submitting and they were there and they were still there after I posted. It wasn't until I checked out rigsy's post a few hours later that I realised something was amiss. Hopefully some of the board members who may have been put off by the lengthy post with no pics will take the time to revisit.

    odtexas,

    Resistance is futile because these lights pull you in like a tractor beam! Next step is to maybe get organised and do some tasty finning on the case that you have pioneered so successfully. I did try cutting off a length of section with my benchsaw but when it flew past my ear at 100 mph and was lost in the darker recesses of my garage I thought better of it and took to the hacksaw!

    Regards,

    OTH

  10. #10
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    Very smart looking light there! Like the story about it flying past your ear at 100mph!! Been there dont that, scared the living daylights out of me!

    Could you post up more on your battery pack please. I have been trying to that sort for a while and yet to come up with a good working solution.

    Thanks

  11. #11
    One Gear
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    Yes, more detail on the battery please. I like the mount too. I've been looking to do something like that to get the battery weight spread across the frame and shorten the wire in the process.

    If your pictures were too big, then the upload will fail. But there should have been an error message. You can always post the photos somewhere else and link to them.

  12. #12
    lumen junkie
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  13. #13
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    Quote Originally Posted by OverTheHill
    I did try cutting off a length of section with my benchsaw but when it flew past my ear at 100 mph and was lost in the darker recesses of my garage I thought better of it and took to the hacksaw!
    As a woodworker who has witnessed some ugly accidents, it gives me the shakes every time I hear something like that Were you cutting through the channel in one shot? Best to make shallow cuts through one wall of the channel at a time, so in the case of your U-channel, 3 cuts. And when cutting the fins it's better to work with a long piece and then cut it to length after the fins are done. Be safe.

    And, once again, nice light!

    JZ
    It's not about speed, it's about lack of control.

  14. #14
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    Quote Originally Posted by JimZinVT
    As a woodworker who has witnessed some ugly accidents, it gives me the shakes every time I hear something like that Were you cutting through the channel in one shot? Best to make shallow cuts through one wall of the channel at a time, so in the case of your U-channel, 3 cuts. And when cutting the fins it's better to work with a long piece and then cut it to length after the fins are done. Be safe.

    And, once again, nice light!

    JZ
    Yeah I hear what you are saying. I am always wary using the bench saw because it is such a powerful piece of machinery. I did have thick working gloves on and eye protectors and also had the presence of mind to keep out of line of the blade. Luckily all I have to show for it is an amusing story!

    As requested further details of the battery pack. I based my design on this post on CPF which is why I referred to it as the “Dynamite” battery pack:

    http://www.candlepowerforums.com/vb/...d.php?t=243369

    One thing I didn’t really like about the original design was the copper end caps and the way he has a contact strip for the positive lead to the copper cap at that end. I felt over time the contact might possibly deteriorate and lead to a short.

    I therefore decided to make a more permanent contact at the +ve end by using an inset cap with a contact fixed to it. I made the contact from an Allen bolt that I ground the head down to about 2mm on a grinding wheel. I then bolted the contact through the inset cap and fixed it with a nut. This then gave me a post to fix the +ve lead to and then another nut on top to lock that into place. I didn't buy the inset cap by the way it was just something I had lying around. It is actually a disposable end cap which comes on a large roll of PTFE water pipe to stop dirt getting in the end on site. You might have to do some hunting around if you want to employ this method or come up with something else.

    At the –ve end I used a cut down spring contact from a battery case and soldered the –ve lead to it and ran the positive lead to the other end. I also fixed a cable tie to give some strain relief before it exits the end cap. I have been meaning to silicone this in place which will also seal the exit hole for the lead but you could also use a rubber grommet. I hope this is all reasonably clear from the pictures I posted.

    The main body is made from 22mm plastic overflow pipe which is the standard size here in the UK and an almost perfect inside diameter for 18650 batteries. Any slack is taken up by the tension provided by the –ve spring contact if you get the length of tube just right (150mm in my case). The outer sheath is a length of old 25mm inner tube I had and is quite a tight fit. The nice thing about this is it holds the plastic end caps solidly in place and is easily rolled back from the +ve end to gain access to the batteries. I obtained the plastic end caps at a local DIY store (B&Q for those based in the UK). They are described as 22mm chair ferrules which (surprise, surprise) are meant for going on the bottom of metal chair legs

    The frame mount is this one from DealExtreme:

    http://www.dealextreme.com/details.dx/sku.12000

    It has two different radiuses (radii?) on the rubber block, the smaller for the battery side and the larger for the frame so again near perfect for the job and it comes with the Velcro (hook ‘n loop) straps. I only use one of these for my 2 x 18650 but you might need 2 mounts if you intend to make one for 3 or more batteries. Another thing I considered is that Blackburn (road) pumps (of which I have a number) have frame mounts which seem to fit the 22mm pipe exactly. It is a bit tighter fit with the rubber sheath in place but still an option you might want to consider. You could then mount the battery pack down at the bottle cage for instance as an alternative.

    I hope I have covered everything and that what I have written makes sense with the pictures. If there is anything you don’t understand, please come back to me or if you can think of an improvement to the design, by all means let me know. One thing I still don’t really like is the external +ve wire – it offends my design sensibilities! I have been toying with the idea of creating a battery pack from metal tubing and using the tube as the earth just like a flashlight. You could also have screw-on end caps which would be another really nice feature. Just something else to add to the list!

    Regards,

    OTH
    Attached Thumbnails Attached Thumbnails Picasso Light-pict0186.jpg  

    Picasso Light-pict0187.jpg  

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    Picasso Light-pict0189.jpg  


  15. #15
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    My first attempt at a holder for 18650 cells was along the lines of the dynamite. I found that the cells would lose contact with each other when riding through really rough sections. A stiffer spring probably would have solved that but I ditched that holder and now have made a few 5 cell round holders. They have worked perfectly.

  16. #16
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    Quote Originally Posted by Vancbiker
    My first attempt at a holder for 18650 cells was along the lines of the dynamite. I found that the cells would lose contact with each other when riding through really rough sections. A stiffer spring probably would have solved that but I ditched that holder and now have made a few 5 cell round holders. They have worked perfectly.
    I think your 5 cell holder is one of the coolest DIY jobs I have seen and I have bookmarked your post detailing it. If I ever get any machining capabilities I will definitely have a go at making something similar.

    My version of the dynamite holder does not suffer from contact problems you describe for maybe one or two reasons: 1) The ID of the plastic overflow pipe is a very close fit with 18650 batteries leaving very little room for them to move about 2) The insert cap modification that I employ compresses the -ve contact spring quite a bit and the inner tube sheath holds it all in place quite nicely.

    If you shake the holder in your hand off the bike you can't feel the batteries move at all. Admittedly I am only using 2 batteries and I don't think the dynamite holder would be suitable for 5 x 18650 batteries without some form of modification. Your cartridge approach is much more appropriate.

    Regards,

    OTH

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