I'm building a UV lightbox and I'm curious what size people think would be the most useful. Right now I'm considering an exposure area of either 6x8 or 8x10 inches.
The latter box offers 67% more working area- but it would be significantly more expensive. I'm just not sure if it would actually be useful for the types of projects most people do at home.
I'm using UV LED's for this project. I've done numerous tests using a variety of UV LED's and all of them have worked reasonably well. LED's in the 390nm wavelength seem to work best. Arranged tightly enough I get very nice, even, consistent exposure on all of the different presensitized boards I tested. The LED's themselves are not expensive in quantity, and even the cheapies from Hong Kong available on eBay worked fine during my testing. (I tested all the LED's before use- every so often I had one that was noticeably darker than the others and I tossed it).
The problem? The PCB I need to mount the LED's gets expensive fast. In protype quantities it's about $55 per board for two 6x8 boards (it's a double sided lightbox). That cost jumps to $75 for an 8x10 board (plus the cost of additional LED's). Those costs drop dramatically in quantity so I'd rather design a board and controller people could make in quantity- hence my question- 6x8 or 8x10?
I estimate I can drive about 640 LED's using a 12 volt (13.6 really), 4 amp power supply I have handy. 4 LED's x 3.4V drop = 13.6 volts. 4 amp = 160 sets of 4 (at 25ma per set). That gives me a maximum of about 300 LED's per side- enough for either size. 6x8 would require about 140 LED's per side and the 8x10 would require about 240 per side. (If my math is off please let me know- I'm more than a little tired at the moment).
Any thoughts?
Has anyone else done any testing of UV LED's for lightbox use? If so what were your results? What model LED did you use? Output? Size? Wavelength? Voltage drop? Viewing angle? What resists did you test it on?
The latter box offers 67% more working area- but it would be significantly more expensive. I'm just not sure if it would actually be useful for the types of projects most people do at home.
I'm using UV LED's for this project. I've done numerous tests using a variety of UV LED's and all of them have worked reasonably well. LED's in the 390nm wavelength seem to work best. Arranged tightly enough I get very nice, even, consistent exposure on all of the different presensitized boards I tested. The LED's themselves are not expensive in quantity, and even the cheapies from Hong Kong available on eBay worked fine during my testing. (I tested all the LED's before use- every so often I had one that was noticeably darker than the others and I tossed it).
The problem? The PCB I need to mount the LED's gets expensive fast. In protype quantities it's about $55 per board for two 6x8 boards (it's a double sided lightbox). That cost jumps to $75 for an 8x10 board (plus the cost of additional LED's). Those costs drop dramatically in quantity so I'd rather design a board and controller people could make in quantity- hence my question- 6x8 or 8x10?
I estimate I can drive about 640 LED's using a 12 volt (13.6 really), 4 amp power supply I have handy. 4 LED's x 3.4V drop = 13.6 volts. 4 amp = 160 sets of 4 (at 25ma per set). That gives me a maximum of about 300 LED's per side- enough for either size. 6x8 would require about 140 LED's per side and the 8x10 would require about 240 per side. (If my math is off please let me know- I'm more than a little tired at the moment).
Any thoughts?
Has anyone else done any testing of UV LED's for lightbox use? If so what were your results? What model LED did you use? Output? Size? Wavelength? Voltage drop? Viewing angle? What resists did you test it on?