The flexible PCBs are insanely expensive in small quantities. If you're doing this on a curve like the Daft Punk helmets, I'd suggest single-line or dual-line PCBs with a vertically oriented row of LEDs plus a driver for 8 or 16 as applicable; SPI or I2C between. Not good if you want to be able to see through the LED matrix from behind, though. Hand-soldering the LEDs into an array is not so bad - use a wooden jig with a CAM-drilled hole matrix to get the spacing perfect even in a hand-built array. Red LEDs run about a nickel each in quantity.
Some commonly available flexible RGB LED strips have LEDs roughly every 16mm, if that's close-packed enough for you, and they are cuttable into groups of three. Some trace-cutting and soldering is required to drive them individually, though. A 5-meter strip (300 LEDs) is about $30 shipped from Hong Kong. RGB takes 3X the I/O, however, for 360 LEDs worth. * Drew Van Zandt Artisan's Asylum Craft Lead, Electronics & Robotics Cam # US2010035593 (M:Liam Hopkins R: Bastian Rotgeld) Domain Coordinator, MA-003-D. Masquerade aVST * On Sat, Jan 21, 2012 at 2:59 AM, Tom Metro <[email protected]>wrote: > Nuno Sucena Almeida wrote: > > ...if you want to avoid too much soldering, consider using a led > > matrix, instead of individual LEDs. > > That was my first thought as well. It'll give you a perfectly consistent > LED spacing. But in addition to it not conforming to the curve, and that > these types of matrix modules are a tad bulky, you would still have some > soldering challenges. You'll still have a bunch of pins (12 for example) > on each module and you'll have to mount it to perf board or sections of > rigid PCB. You could, for example, put each display on its own PCB > segment, and join the segments with some solid wire jumpers, which would > act as a hinge. > > Another possibility is to use flexible LED strips, like these: > > http://www.google.com/products?as_q=flexible+led+strips&num=100&scoring=p&as_epq=&as_oq=&as_eq=&price1=&price2=&as_occt=any&show=dd&safe=active > > You'd presumably use as many strips as you want rows in your display. > > But they have two problems. One is that they typically don't have a > dense enough spacing to make an effective display. The other is that > they are typically wired in series, so you'd have to hack it by cutting > traces and tacking on wires, which would be a mess. > > The ideal solution would be to create a custom display board using the > same flexible PCB substrate used for the flexible strips. Incorporate > the matrix driver onto the board. Use SMD LEDs and attach them with > solder paste and baking in the oven, rather than individual soldering. > > Though not a quickie project. > > Also, consider using RGB LEDs so you can create even more effects. > > -Tom > _______________________________________________ > Hardwarehacking mailing list > [email protected] > http://lists.blu.org/mailman/listinfo/hardwarehacking >
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