Intro: LED Backlit Glass Whiteboard
I have a tiny desk in my room and what little space is available tends to get used up quickly. This can create a bit of a problem when it comes time for homework. Between whatever was already on the desk, my laptop, and my notes from class, I have no space left over for a notebook in which to do calculations. I figured a whiteboard would help, but as a broke student, I couldn't afford one. My friends and family are aware of my strange DIY junk hoarding habits and as a result tend to give me their electronic detritus. Recently this old behemoth of a printer entered my possession. I immediately saw the potential in the scanner bed for solving my whiteboard problem.
Space saved, junk repurposed, plus, it makes calculus and physics homework look all scifi snazzy!
Step 1: Scavenge Scanner Bed
I began this build by first harvesting the glass scanner bed, along with the metal track along which it slid. I figured I could use the track to make the whiteboard movable, although I eventually threw out that idea, left the whole unit stationary on the wall and used the metal hardware to magnetically attach dry erase markers and various reference papers to the board.
Step 2: Cut and Drill Plastic
Fortunately for me (since I'm a terrible planner), the metal hardware to which the glass was attached had gaps in it which corresponded almost perfectly to the sizes and shape of the switch I wanted to add as well as the necessary mounting holes.
I drilled through one of these gaps on either side of the plastic. The resultant holes would later be used to hang the whole board on the wall with nails. I also hacked open a switch sized whole in the center of the board. Knowing that one side of the terrible cut would be against the wall and the other side hidden behind metal gave me some peace of mind since, as you can see from the pictures, I'm not exactly precise with my rotary tool and my cut lives up to the term "hacking".
Step 3: Create Battery Mounting Bracket and Marker Holder
Next I created a pair of upward facing hooks out of Sugru across which I could hang a dry erase marker. I don't have any really great pictures of them unfortunately, but you can kind of see one (in blue) near the switch hole.
During the 24 hours that I left the Sugru to dry, I did the math on the LED circuit and decided on the physical layout of the lights. I chose the top and the side of the glass because that was where I could best hide LEDs. The top is obviously opaque, but what may not be clear from the pictures is that there is an opaque strip running down one side of the glass as well, perfect for hiding wires and LEDs
I had originally wanted 4 LEDs running along the top and 4 along the side, but at 3 V an LED, that would have required a 24 V power supply. . I realized that since 2*9 V would give me 18 V, my best bet would be mounting 2 9 Vs and using only six LEDs; 3 on top and 3 on the sides.
Once I knew my power requirements, I could make a battery mounting system. I have a pretty large supply of old brass mounting brackets lying about. A little bit of searching followed by a little bit of bending was all I needed to find two pieces of brass that I could screw into the plastic to hold the batteries in place. In order to get power out of the batteries the way I had them held in place, I cut a 9 V battery connector in half and attached the positive lead to one battery and the negative lead to the other, allowing me to maintain the 18 V series necessary, and keeping the batteries oriented in such a way that they laid flush against the wall.
Step 4: Create Circuit
I next did a test layout of the circuit so I could be sure that it would work and so I could be sure that I would ultimately be happy with the light pattern given off by the LEDs. Once I was happy with all of that I added in the switch and tested again. Satisfied that it all worked, I soldered it all together, hid the wires, hot glued all of the components in place and mounted it to the wall.
All in all I love the project and use it every night while doing homework. Not only does it save me desk space, but I feel all sciency while doing it!