Introduction: LED Booklight
A small LED lamp, designed to slide in the back of a book or magazine. Powered by a battery salvaged from an empty Polaroid film cartridge.
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Step 1: Parts List
I got the idea after being given a few batteries, removed from a cartridge of Polaroid film after all the photos were used. Its a 6V battery, and, considering its short life in the camera, should provide power for a while. I came up with the idea after tinkering for a while, trying to think of a way to use the thin packaging of the battery. Sliding the paperclips on to the battery seemed like a good way to make contact, and I just kind of went from there...
I made a few versions; one that could be taken apart, using Molex connectors, and another one, that can be folded up. Both versions are described here
Here's what you need:
- Battery, removed from empty cartridge of Polaroid film
- High efficiency white LED (5 mm diameteter)
- 220 ohm resistor
- 4 (large) paperclips
- 2 small pieces of stripboard (3 holes x 14 holes)
- LED lamp holder
- Strip of ribbon wire (harvested from old radio etc.) or 2 connector wires
- Assorted Lego parts: axle, pins, connectors. See photo.
- 2 Molex connectors (male and female ends), if making this kind.
First, I quickly set up the LED and resistor in some breadboard, to determine which contact was which. With the contacts facing up and at the top, the positive is on the right.
Step 2: Make the Base
Cut the outer part off of 2 of the paperclips, and bend them at the curve to form a right angle. Solder these to the outer edge of the other 2 paperclips. Put them in a clamp and heat the paperclips with a lighter, and apply solder to the seam.
Use a paperclip to slightly enlarge the holes in a pieces of stripboard, in the middle row, 3 holes in from each edge.
Slide the stripboard over the upright parts of the paperclip contacts. Slide this onto the polaroid battery to check the alignment, then carefully remove it to a piece of regular cardboard for soldering. Solder the stripboard to the paperclips.
If using the Molex connectors (if not, proceed to next step):
Trim the end of the paperclips so that about 1/4" or so remains. Place the female ends of the connectors on the paperclip ends and solder in place.
Step 3: Make Lamp Top
Insert the LED into the holder, and replace the stopper. Slide the LED leads into holes in the stripboard, making sure the negative lead is on the left. Add the resistor to the left of the LED, with one end in the same track as the negative LED lead. Solder both components in place. Trim excess of the leads.
If using Molex connectors:
Solder scrap pieces of paperclip (or connector wire) into male ends of connectors. Place these into the female ends on the base; slide the other piece of stripboard onto the male connectors, then solder into place. Add the resistor and LED as desribed above, making sure the resistor and LED are in the same tracks as the posiitve and negative connectors. Solder components in place.
If you're making this version, you're done!
Step 4: Make Support
Connect Lego parts as shown.
Use epoxy to glue the Lego support to the base, then glue the lamp top to the support.
Step 5: Connect Wire
After glue has set, strip both ends of ribbon wire (or hookup wire). Place the ends in the appropriate tracks of the lamp top, to connect with resistor and LED. Make sure ribbon wire is appropriate length, then plce wires in holes of the base, to connect to the paperclip contacts, and solder.
Reinforce joints and connections with glue, to make the lamp sturdier (especially at the base, where the paperclips are soldered to the stripboard on the base).
Voila. To use the lamp, just slide it onto the battery, so the paperclips touch the contacts.
While I like the simplicity of the first version I made (using only paperlips), the one with the Lego support is the most functional. It can be folded up, and its a bit taller, and can be adjusted, so can provide more even illumination to the page.