Introduction: DC LED Night Light
First off, these pictures (had these for the longest time) should be the last you'll have to see of my stupid 3.2 MP camera (gave it to my little brother)... upped to 5.2 MP :)
Here's the deal...
Need a light to brighten the dark hallway above the stairs so you can navigate safely into the bathroom without tumbling headlong down those stairs? We did and the store bought versions with the bulbs didn't last long (especially since my sister likes to tear the light out of the socket and throw them). Hence, I figured out a more robust night light that costs practically nothing.
2. Heat gun (or other form of high temp. flameless heat)
3. Hot glue gun
4. Flat head screw driver
5. Vice (I didn't have one, so I "improvised")
6. Soldering Iron
8. Drill w/ bits
1. Small electrical wire
3. DC wall wart supply
5. Electrical tape
6. Film canisters
7. White LED
8. Resistor (value depends on output of supply)
Warning: Electricity can hurt, maim, and kill... but then again, so can other things. You are held responsible for your own actions (unless you're a minor, then your parents/legal guardians are held responsible). Objects in this Instructable become hot and can burn. That being said, let's get started.
Step 1: Let's "Trash" It
We need to take the supply apart, but first we need to test the "true" voltage being supplied. The wart I had said the output was 4.5V (you can barely make it out in the first picture), but when I tested the output, it was at 9V (which would definitely fry the 4V LED). I suggest unplugging the wart and keep it attached to the multimeter until the transformer is drained of its juice.
Now that we know the output, we can take it apart. There are several ways to go about this.
1. You could put the supply into a vice and squeeze it until the seams break.
2. You could use a hack saw to carefully cut your way into the supply.
3. Or you could do it the unsafe way, by melting the seams using an old soldering iron (technically wood burning) that the tip has been murdered from neglect.
Yes, I went with choice number 3 (not the wisest idea, but it worked and was fast). If you choose to also do this version, I beg of you to take proper precautions beforehand (vented area, goggles, etc). Melt only deep enough around the entire supply to give you enough leverage to use the screw driver to pop the cover off the rest of the way.
Step 2: Prepare the Cover and Circuit
Now that we're inside, we need to figure out how we want to hook up our circuit and where everything will be located.
First, we'll make a hole for the LED using a drill (or in my case an iron). I made mine near the top/center.
Second, the hole for the switch using the same method. Made mine near the bottom/center.
1. Solder the resistor onto one of the legs of the LED (doesn't matter which one, as long as the current goes through it).
2. Solder the resistor to a wire.
3. Solder the wire to the switch.
That's it for the circuit until the next step...
Step 3: Rest of the Circuit and Case Fit
Now we can trim the DC supply wires down to the length we need (about 3 inches) and bare the ends (make sure they don't touch).
Depending on which side of the LED is positive (shorter element in LED) and which is negative (larger element in LED), solder the DC supply's wires onto/into the circuit accordingly (Negative goes to the negative side, positive to the positive side). In my case, I soldered the positive to the switch and the negative to the LED. Wrap the wires up with some tape.
Get your hot glue gun and glue the pieces into the holes we've made in the cover. Let it harden. Put a dab of hot glue over the LED to help diffuse the light.
Now we get to put the puzzle back together again. Carefully fold the wires into the case (leave absolutely no wires outside the case) and press the cover back onto the base. In my case I had a small gap, but it doesn't matter cause it's going to be "welded" shut soon...
Step 4: Finish It Up
Warning toxic fumes may be emitted. Do this only in a well ventilated area.
Take the film canister and cut long strips out of it. Using your heat gun (or flameless heat gun), melt the strips into the sides of the supply (see pictures).
Once all the sides have been plastic "welded" shut, you can add an extra protection layer using electrical tape.
Now go plug it in and hit the switch. It's a robust night light (you can also use it for a 10 second flashlight. More time if you use a larger supply voltage).
The two things I'd change about it later is:
1. More LED's (I only had one white LED at the time)
2. A stronger switch like a toggle (sister bit the other one off. Can still turn on and off using a toothpick, but unable to reattach switch without taking it apart. Lucky for her it wasn't a bulb night light)
Once again I apologize for the pictures, but these are the last Instructable pictures (I have 3-4 pictures for the forums still) taken using my bad camera. I did try to focus in on the smaller details using my pinhole lens (which worked well to some degree).