Introduction: Automatic Drawer Lights
My computer desk is in the back corner of a large living room. The room only has one ceiling light in the very middle of the room. When ever I need to look though a drawer in my computer desk I have to grab a flash light to see what I am trying to get. I have finally said enough is an enough. So now I am here to share my fix for my problem. My plan is to have a led light come on as soon as the drawer is opened. I also wanted to use as may harvested parts as I could. So stay tuned and see what I have came up with.
Step 1: Getting the Parts for the Project.
OK so like I said in the intro I want to used as many reused parts as I can. At my job I work on forklifts. And it seams like every week we get one in that has broken LED tail lights. Most of the time all that is broken is the lens. Well at my job if the lens is missing a piece or even just cracked they want it replaced. They just toss the old ones in the trash. I asked them and they said if I really wanted them I could take them. So as of now I have 3 saved up for a project. We will need some wire for this thing to work. I saved a wiring harness that we replaced with a new one from work. We will also be needing 1 switch per drawer. My desk has 3 drawers that I want to light up. So I need 3 switches. For how I am using them I need switches that are normally closed when the button is not being pushed. The forklifts I work on have micro switch's in them also. They use them for seeing if the e brake is on or if some one is sitting in the seat. We are always replacing worn out seats. The new seats come with a new switch so I save the switches out of the old seats. Now we need something to power this all with. The lights I am using are set up for 12 volts. I had a wall wart with a power port that I had saved from something. So I am going to use that. I also decided to add connectors to my LEDs so I can remove one if it gets damaged or quits. I also want to be able to remove the LED easily if something happens so I decided to use Velcro as well.
Step 2: Needed Tools
Hes is the list of tools that I used for my project.
Wire strippers and crimper
Pen or Marker
Scroll Saw or Hack Saw
File or sand paper
Step 3: Getting the Lights Ready
OK so now the first step on getting the circuit board out of the plastic housing. You need to remove the lens first but in my case the lens was already fully broken off. The next thing to do is get the back plastic off. This will require a soldering iron. I could not get the holders for the pins to release so I just desolder them to get the plastic off. Now that the circuit board is free you need to check the traces and see where you can cut at. On the lights that I am using where the pins are soldered on at they are labeled tail, turn, gnd, brake, and rev. For this project we are using the reverse lights (rev). So we will need to trace the rev and ground (gnd) pins. On my lights the rev pin follows the top edge of the board so it was easy to follow. The ground pin follows the bottom edge with a few spots where it joins all the ground together. It is also easy to trace. So now I know where all the traces go I made a few lines of where it would be safe to cut. Now to cut the circuit board I used me scroll saw with a fine tooth metal blade on it. Now with the cuts done we can put the parts we do not need to the side and save them for another project that I am already planing. Now the parts with the reverse leds on them need to have the traces very carefully sanded to expose a surface we can solder to. Now with the traces exposed we can solder the short leads with plugs on them. I also went ahead and added the Velcro to the back of them. Now the lights are prepared for when we need them.
Step 4: Adding the Lights, Switches and Wiring to the Desk
OK so first thing we need to do on this step is pull out all of the desk drawers. Now take some small strips of Velcro and put them in the desk close to where the edge of the drawer would be if closed. Now add Velcro to the micro switches and place them in the desk. The reason for using the Velcro is so you can adjust the switches tell you find that perfect spot where they work the best with the drawer. Now I added Velcro to the back of the lights and mounted them where I wanted them to be. With the location of the switch and lights set you can now measure the light of wire you need to go from the positive of the light to the switch. After cutting the wire to length I soldered them to the micro switches. I soldered them to the normally closed (NC2) terminal one the switch This also would be a good time to add the connecters to the end of the wires. With all the wires solder to the NC2 terminal on the switch place them back in the desk. Now here it gets a little harder. We now need to connect all the switches and power lead together. We will be using the common (C1) terminal of the switch this time. I went to the farthest away switch and soldered a wire to it. Then to the middle switch. Take the wire from the first and take a new wire and solder them both to the middle switch. Same thing for the last switch but this time we need about 4 foot long lead of wire for the positive power in. Now for the negative lead. Here we do pretty much the same thing but instead of hooking to a switch we are hooking to the negative lead of the LED. We also will be using spade connectors instead of soldering since we soldered leads to the leds for removal. Now all the wiring is done you need to staple the wires up out of the way. This way the drawers do not catch on them when you open or close them.
Step 5: Adding Power and Finishing Up the Project
For this step we need the wall wart, power plug, solder and a soldering iron. I started by removing the leads on my power port. I then checked my wall wart for its polarity. Mine has a center positive. So this means when I solder my power port to the wires going to my leds I need to make sure my positive wire is soldered to the center pin on my power port. So next we solder the wires to are power port. After that is done it is time to plug in are wall wart and test our lights. Now pull out each drawer and see if you lights come one. On the switches I used I hear a click every time I open or close my drawer. That is how I know they are working. Well I hope you enjoyed my instructable. Thanks for looking.