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Power savings, you say? .............. 
Can't wait to see how this turns out, I hope it at least saves power.
I'm back Spice orange FTW!no, I played mine so much the joystick is loosepalmertech wrote:The actual analog, or the cap? I may have an extra cap somewhere around here...
And I can't sell it, it is my only one not torn to pieces.
I wanted the controller to play with (on the system) I'm backKurt_
Message subject: So like, SMD LED's!
Folder: Sent messages
So what MCD rating / luminous flux did those LED's you used have? I gotta make an 850 nit backlight for a 5" LCD and it's gotta be damn bright, so I'm hoping to one-up you. No, I kid. But seriously, what's the rating?
Also, 3M samples ship to worldwide, I'm sure the UK is no problem.
daftmike
Message subject: Re: So like, SMD LED's!
Folder: Inbox
the leds i used in my psone screen, were very ordinary plcc-2 leds, 600mcd and a beam angle of 120°, and are about 1.8 lumens each at 20mA.
I don't know the exact efficiency of the psone screen light guide, polariser, diffuser etc., but it's certainly not more than about 4% (a fairly educated guess) so my screen sent ~ 1.44 lumens out the front and is therefore 170nits or thereabouts in brightness. which seems about right compared to the ccfl screen (a four led mod can't be much more than 40nits!)
(nits translates to lumens/m^2, psone screen area = 8.4x10^-3 m^2)
So if you want your screen to be at least 850 nits you'll need it more than 5 times brighter than mine.
There isn't room for many more leds so i suggest using more efficient ones.
I have experience with luxeon rebel leds, they are great, i was going to use them for my screen but couldn't really justify the expence at the time. (top-binned rebel pwc1-0100 parts cost about 7 euros each in small quantities, my leds cost 20 cents)
The only thing i will say is that the rebel package is a bit difficult to work with by hand it's something like 4.5mm x 3mm and the pads are tiny, but that comes with the territory.
Anyway they are fantasticlly efficient, about 100lm/W at 350mA (the ones i used are ~25lm/W @ 20mA) they're about the same size as the leds i used so if you had 20 in the same configuration, 10 on top, 10 underneath and drove them conservatively at 30mA (they're rated to 700mA with adequate heatsinking) you should end up with a display of about 900nits brightness.
If you only used 10 in total you could drive them with twice the current for about the same brightness but there might be heatsinking issues etc.
of course you may know all this already, in which case i apologise, i tend to type a lot.
ps. thanks for the heads-up about the 3M samples, i'll see if i can get a couple of sheets and do some testing.
Kurt_
Message subject: Re: So like, SMD LED's!
Folder: Sent messages
That helps me out quite a bit. LEDs aren't my forte. I can my hands on some PLCC-2 2500 mcd LEDs off of eBay. 50 for $20 shipped to my door. If I'm correct, that'd already make it four times brighter than your screen. With the 3M stuff, we'll see, I got it today.
daftmike
Message subject: Re: So like, SMD LED's!
Folder: Inbox
leds sort of are my forte, (i did some r&d for philips during my degree) unfortunately, i can say with absolute certainty that ebay seller is lying about his leds. there is no way they can make 2500mcd, maybe a tenth of that.
you really need to get leds from a reliable source, it's a shame but almost all hong kong/chinese sellers on ebay are blatantly lying about their mcd figures, because candela is a function of beam angle it's really easy to fudge the numbers and stick a nought or two on the end.
you could feasibly fit twice the number of leds i did in the same space, but then you risk losing output due to excess heat so it likely won't be twice as bright, unfortunately you get what you pay for when it comes to leds, and the cutting edge is pretty expensive.
Kurt_
Message subject: Re: So like, SMD LED's!
Folder: Sent messages
The problem is it's not for me, it's for my University's solar car LCD, so $20-$25 is about as expensive as I can go. Any recommendations?
daftmike
Message subject: Re: So like, SMD LED's!
Folder: Inbox
ok, 850 nits might be slightly out of reach then
although this auction for 10 luxeon rebel 70s looks promising
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :IT&ih=010
they aren't the top bin but if you used 5 on top, 5 on bottom and drove them at 60mA you should get very near 850 nits. regardless it would be BRIGHT!!
otherwise go for those ebay plcc-2s and pack as many in as you can, i reckon you could fit 20 each top and bottom, with a 3M sheet or 2 you should get a nice result.
Kurt_
Message subject: Re: So like, SMD LED's!
Folder: Sent messages
What's the difference between PLCC-2, 4, and 6?
And what's the highest brightness I can expect out of them, to avoid scammage?
Also, those luxeon's are rapage. They go from led to BALL OF LIGHT. If only they weren't so expensive...
If you don't mind, can you give me your opinion on the following?
http://search.digikey.com/scripts/DkSea ... -1329-1-ND
$1.23 each, 1350 mcd. I can get like 16 maybe.
http://search.digikey.com/scripts/DkSea ... -1361-1-ND
$0.86 each, PLCC-2. I could get around 20.
daftmike
Message subject: Re: So like, SMD LED's!
Folder: Inbox
plcc is the name of the chip package, the difference between 2,4,6 etc. is the number of pins and the package size.
avoid ebay. the majority of sellers have no documentation to back up their ludicrous luminosity claims. i would be sceptical of a 120° led with more than 500mcd if it wasn't a decent brand name (edison, kingbright, tru-opto, osram, nichia etc.) or didn't have good datasheets.
a good tip would be to look for a luminous flux rating in Lumens(lm) rather than luminous intensity in candelas(cd) as lumen output gives a better idea of the amount of light an led produces and most if not all dodgy leds won't have a luminous flux rating.
power leds are fantastic fun, i have a couple the new multi-core cree mc-e that put out about 1000lm that's approaching car headlight territory.
luxeon really pioneered power leds in such a small package when they came out a year or so ago, i've played with them a bit in the past and they're so versatile, you can stick them anywhere so to speak
i've actually just bought 20 more from that auction with a view to making a new backlight
good job on finding those leds, they're a little expensive(even considering how good they are) but both excellent quality, i really like the osrams and if i had your budget i would go for them.
a quick calc shows you should get more than 300nits on a 5" screen with 16 of those osrams at 30mA and the leds in that second link are almost identical specs to the ones i used in my psone screen.
Kurt_
Message subject: Re: So like, SMD LED's!
Folder: Sent messages
300 nits? Thanks a bunch, that'd be fabulous. Because with the added 3M films, I'm POTENTIALLY looking at a 165% brightness INCREASE with all the 3M films I have. They all look extremely high quality. That;s around 600 nits, which I'm sure will be fine, since power consumption will be cut in half still.
Daftmike
plcc is the name of the chip package, the difference between 2,4,6 etc. is the number of pins and the package size.
avoid ebay. the majority of sellers have no documentation to back up their ludicrous luminosity claims. i would be sceptical of a 120° led with more than 500mcd if it wasn't a decent brand name (edison, kingbright, tru-opto, osram, nichia etc.) or didn't have good datasheets.
a good tip would be to look for a luminous flux rating in Lumens(lm) rather than luminous intensity in candelas(cd) as lumen output gives a better idea of the amount of light an led produces and most if not all dodgy leds won't have a luminous flux rating.
power leds are fantastic fun, i have a couple the new multi-core cree mc-e that put out about 1000lm that's approaching car headlight territory
luxeon really pioneered power leds in such a small package when they came out a year or so ago, i've played with them a bit in the past and they're so versatile, you can stick them anywhere so to speak
i've actually just bought 20 more from that auction with a view to making a new backlight
good job on finding those leds, they're a little expensive(even considering how good they are) but both excellent quality, i really like the osrams and if i had your budget i would go for them.
a quick calc shows you should get more than 300nits on a 5" screen with 16 of those osrams at 30mA and the leds in that second link are almost identical specs to the ones i used in my psone screen.
