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Reader Booklight
Thought you would be interested in seeing the booklight I’ve built for my Sony Reader. It is the result of about a dozen attempts and I now am using it regularly to read in bed. Along the way I tried several commercial booklights; all of which came with baggage that presented problems. This light overcomes a few of them.+
1. It uses 3 Light Emitting Diodes (LEDs) each operating at its rated current (i.e. 20 milliampers). This current is adjustable (still testing to find the best operating parameters). While 2 LEDs can provide adequate light I added a third for experimental margin. The LEDs are recessed in a housing at the top of arm positioned above the Reader. They are recessed in order to eliminate reflections of the LEDs on the reading surface. The shape of the box helps focus the light on the reading surface.
2. It uses 4 Nickel Metal-Hydride batteries of the AAA size. While it is possible to use much smaller batteries, even button sizes, I chose these in order to have a reservoir of power. The reason will become apparent as you read on. I chose rechargeable type batteries for long term economy.
3. In order to charge the batteries, I am using solar cells. Since solar power is not at its best every day here in New England the extra capacity of the batteries carry me over during the cloudy days when my solar charger is not able to generate enough power. One of the tests that I am presently conducting is to see how many days the solar-charged batteries will hold out. Most recently the batteries were still going strong after 15 days during which I used the Reader in bed for 1 to 2 hours every night. Unfortunately I had to interrupt that test so a new test is in progress..
4. In addition to the solar charging facility, my booklight incorporates a 30-minute timeout. That is, I turn the light on when I begin reading and it automatically goes out after 30 minutes. The reason for this is that often I will fall asleep before turning the light off and the timeout avoids depleting the batteries unnecessarily. The timeout period is also under test to determine its most convenient length. I find that having to turn the light back on every 30-minutes acceptable because it involves simply depressing a momentary button on the side of the assembly.
5. The light assembly is removeable during the day. It also incorporates a plug-in receptable that permits connecting to the solar charger. This way I can take the Reader with me during the day while the sun is charging its batteries.
My experiments continue. At the moment I’m working on a circuit for charging the cheaper alkaline batteries; a solar charger that doesn’t have to be repositioned during the day; a more compact and elegant assembly and etc.
One of the attached photographs shows the light attached to the Reader (it slides into the turned down flap of the Reader’s leather case). The second photograph shows the light assembly alone and the solar charger. The plug at the end of the charger cord inserts into a receptacle on the light assembly.
Joe Maina
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