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MaxM brightness level comparisons?
I'm having trouble getting a feel for the brightness level of the MaxM, but I was looking at using one as a lamp. Let's suppose I put it in a darkened room on my desk, pointed at the ceiling. At full power, how bright does that seem compared to more normal lighting sources?
Given the mcd rating, and assuming it's the same dispersion angle as regular BlinkM, an on-line calculator suggests I'm in the neighborhood of a 100W incandescent bulb's light output. But the spec sheet says max power draw is 5.5v * 250mA, and Wikipedia tells me that the lumens/watt level for LEDs is only like 5x incandescent, not 70x.
From that, I think I'm looking at "bright reading lamp" rather than "normal room lamp", but I'd love to hear what people actually experience.
Thanks!
Given the mcd rating, and assuming it's the same dispersion angle as regular BlinkM, an on-line calculator suggests I'm in the neighborhood of a 100W incandescent bulb's light output. But the spec sheet says max power draw is 5.5v * 250mA, and Wikipedia tells me that the lumens/watt level for LEDs is only like 5x incandescent, not 70x.
From that, I think I'm looking at "bright reading lamp" rather than "normal room lamp", but I'd love to hear what people actually experience.
Thanks!
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Inappropriate?The "mcd rating" is in millicandelas. A candela is a measurement that depends on the viewing angle. I just picked up a MaxM today and I noticed (with some sadness) that the blaster's LEDs are extremely directional. The shape of the LED acts as a lens, so nearly all of the light comes out in one direction. This means it has a high luminous intensity (in the same ballpark as a 100W bulb), but a low luminous flux, since the light is emitted only at a narrow angle.
So, if you're looking right down at these from the top, you'd say they were bright, but they're not going to light up a room.
Fortunately, it appears the master board can power up to 2A of LEDs, so if you're willing to do some more work on your own, you can assemble some LEDs/resistors of your own, and use them instead of the LEDs on the blaster. -
Inappropriate?From what I can tell the MaxM board can do at least 2A per channel and probably could go to 4A/channel (dont know about trace widths though - would have to watch that). at 24V you could drive some significant loads with a MaxM.
I have driven 1.2A of RGB leds through it (400mA/channel) at 12V and it's a lot of light, though even with 6A of leds on there you're not close to a 100W light bulb in total output. It would be rather expensive as well, don't forget. Assuming a luminous efficacy of 2% for incandescent and a very optimistic 22% for an RGB led, you'd need to drive 9W of LEDs to get the same light output. I drove 14W of LED with it at 12V and can tell you it wasn't close. I'd say you'd need probably 35-45W of LED on average to do the job. Maybe a little less with some specialty leds like luxeon but you'd need some experience to drive luxeon correctly using a MaxM... -
Inappropriate?Luxeon, Crees, and similar LEDs need a constant-current power supply to run them at their brightest. This is because they exhibit this nasty thermal runaway problem (they get hot, draw more current, get hotter, etc. until fzzzt!)
I believe you should be able to run a Luxeon at half-current with MaxM, but I've not tried it yet.
And yeah, getting comparable light output numbers that make sense between incandescents and LEDs is hard. Even commercial LED incandescent-replacement bulbs that advertise a given light output seem off.
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