Hi all, I just took pictures with my LED-light attached to a powered USB-Hub. I have them in a public album but don't know how to get the thumbnails in the post. So here is what you can do:
-Click on my name on the left to get to my profile.
-Click on the albums thumbnail on the right side of the page.
This is the order of the pictures left to right:
1. LED-Light only to give a short glimpse on the lamp. When I picked the lamp up at an electronics store, I was fairly impressed by the array of LEDs.
2. Picture taken of the lamp over the reader, the lamp not powered. Desk lighting was on and still I had to use flash to get a good exposure without shake.
3. Picture taken without flash, just to show how shaky the picture got (so exposure time was very long)
4. I tried to capture the glare at the bottom of the screen (a really bad angle of the lamp for reading) just to show how bright the lamp is
5. Lamp angled so that the brightest spots get on the frame of the reader. The frame doesn't reflect the light so mirror like so that it's not blinding. Actually I found it pretty good and much better than the dim desk light (which has a low wattage) for reading.
Pictures 4 and 5 were taken without any light in the room. So it really was pitch black, reader only lit by the 8LED-lamp.
The 8LEDs make for pretty even distribution. My single LED lamp always showed vignetting so that the brightest spot had to be moved around depending on where I was just reading (top, middle, bottom).
The single LED lamp also had a bright spot, but when angled to a convenient point on the frame, you would only get light on half the screen.
Next step would be a housing for the batteries and USB-connector. Attaching some sort of clip to the housing so it can be used with the readers' cover. I plan on permanently attaching the goosneck to the housing so I won't strain the connector and put a power switch to the circuit. If someone has a similar light and the option for a USB-Battery-adaptor (I found a brand called Revolt), the I think the whole thing could be made by just using a factory USB-Battery adaptor and the LED, utilizing the connector as the switch.
Battery durability:
If you take for example 4 AAA bats. with 1200 mAH you would get 4800 mAH at a voltage (using rechargable batteries) of 4.8V.
The lamp uses 150 mA (max). This gets us to 32 hours. As the voltage drops while using the batteries, there would be a time where the lamp just shuts down as the LEDs have a breakthrough voltage (I don't know where that is).
But lets say due to power drain the voltage drops below the breakthrough voltag after 1/3 of the time, you would still get 10 hours of continuous light.
Ok, sorry for the long post (and any typos)
