You know how you open the fridge and the lights are just on? That's cool and I want that in a lot of other useful places - Like my tool chest. So now I have it and I'm going to show you how to do it too!
This project covers adding LED lights to each drawer of a tool chest—so that it will automatically turn on when the door is opened, and turn off when it's closed. The tool chest I have are Craftsman tool chest. All the dimensions I'll mention are related to a standard Craftsman tool chest.
I have some basic projects tools so the only cost for this project was the material cost. I needed LED Lights, Battery Packs and a switch to turn things off and on. This project cost me about $30 in new materials your mileage may vary depending on your tools and deals you can find on the parts. We'll cover all the parts and pieces in the next step.
The mystery of the fridge lights being on or off when the door is closed is solved in this project. Quick Note, this Instructable isn't as long as it looks. Some steps are just extra information and you can skip the mini physics lesson and skip right to building!
Enough about the why, lets get into the how!
Step 1: Things You Have, Things You Dont
There are some things you may already have and some things you would need. I also used a 3D printer to print some custom brackets; I'll supply the file and dimensions I used if you have one.
Things you may have (basic project tool pack):
Scissors, Tape, Soldering Iron, Solder, helping hands soldering station, electrical tape, wire cutters, some wire (anything will work here, I used leftover wire from another project), needle-nose pliers, caliper.
If you don't a caliper, you can get a good digital one from amazon or Ebay for like $10. I highly recommend one for projects like this to have an easy to read caliper.
Things you probably don't have:
These are the LED Light strip I used. ($8 Amazon Prime)
You could always get some waterproof ones also (for not much more)
Microswitch aka limit switch. ($10 for qnty 20). I installed my lights on 10 drawers but you can never have too many of these for other projects.
LED Light strip Easy Connectors (Optional - $6 for 10, cut in half will make the 20 needed for 10 drawers)
Battery holder. The battery holder you pick will really be a function of how long do you want to go between changing batteries. Since we will be cutting this to roughly 18 inch segments for each drawer, the amp draw is low. I picked these 6xAA holders but there are other options here (including using rechargeable packs). More on this later.
Regarding 3D printing part the brackets If you don't have a 3D printer don't buy one just for this project, buy one because they are awesome. But, if you're not going to get one (you should) just use Moldable plastic instead of buying a 3D printer (which you should).
Step 2: LED Light Strips - Tool Chest So Bright I Gotta Wear Shades
The key here is the low cost, low power consuming and easy to use LED Light strips.
If you haven't used these things before you have been missing out. These things are pretty cheap and can be installed in a wide range of uses. I've installed these lights in my kitchen for under cabinet lighting, in my car for lighting up hard to see spots, and outside (weather proof version) for mood lighting for parties. Once you make a project with these kits you'll be hooked on them.
First thing to know is that the majority of the ones you can buy online are able to be cut into small segments at the indicated marks (typically 3 or 4 inches apart).
For this project I bought a 16 ft strip (standard size) and cut them into 9 inch segments. Doing this gave me 20+ 9 inch segments. I used one 9 inch segment on each side of each drawer resulting in 2 segments for each drawer. This works out to 18 LED lights in each drawer.
Once cut at the noted location, you can use the wire clips you buy, or solder wire directly onto the strips. The first time I used these I used the clips I bought online. They tend to suffer from movement over time and will eventually become a bad connection. I know it seems intimidating but soldering them isn't that hard, just take your time and make sure you have a good connection. I'm not a soldering expert but luckily there are some good instructables by other authors on that subject. If you need some assistance, I'll wait why you go read one of those. Go ahead; I'll be here when you get back.....
Alright, when you have all your sections cut up we can move onto a mini physics lesson, wiring and testing.
Step 3: 1.21 GigaWatts!
No not really. You won't be traveling in time, so you don't need that much.
There are two concepts you don't need to know, but here is some info in case you’re curious. The two concepts are Voltage (V) and milliAmpere hour (mAh). I'm going to make a lot of assumptions, so don't get to nit picky here. This isn't a physics lesson as much as a high level overview. I'll keep the math very simple, or you can just skip to the next step if you don't care lol.
Voltage is the electrical force required to run a circuit. You can think of this in terms of mechanical force like this, to lift a 100lb weight you have to supply a 100 lb force. To run a 12V circuit, you need to supply 12 Volts. It can get deeper than that, but let's keep it simple shall we?
An Ampere (commonly called Amp) is how much current is required for operating, and an Amp Hour is how long you can supply that amperage. Think of it like this, if you have a 10 cups of water and it has a hole it in that leaks 1 cup an hour it would take 10 hours to empty. The 10 Cups here would be your potential miliAmp hours from your batteries and the leak (cups per hour) would be your milliamp hour draw from your circuit. Same thing with amps, if you have a 700 milliamp battery (typical AA battery is something like 2500 milliamps) and your circuit draws 100 milliamps per hour, you could run your circuit for 7 hours 700 / 100 = 7. And yes 0.7 Amps = 700 milliamps.
Let's chat batteries for a second. The light strips are rated for 12V. A single AA battery is 1.5V. My Battery packs are wired in Series (that means the V- of one battery goes to the V+ of the next), so to determine the voltage for the pack multiple your number of batteries by 1.5V. For 12 volts, you need 8 AA and that's starting to get a little big. For this project I used 6xAA which results in 9V. The LED strips can operate at 9V (I think that's the minimum) they are just slightly dimmer than if it was 12V supply.
Updated (thanks to Galah for the correction):
When connected in series Amperage does not add like it does for Voltage. Each battery is roughly 2500 milliamps hour and when connected in series the amperage hour remains constant as the increase in number of batteries is going towards boosting the Voltage.
The light strips I bought were 12V and 20 Watts. I'm only using 9V so i'll use 9 instead of 12 in my calculation. To calculate amps use Amp = Watt / Voltage. 20/9 = 2.22 Amps for the entire light string. I cut mine into 20 pieces (and used two per door, so i have 10 final sections). That results in 2.2 / 10 = 0.222 amps or 222 milliamps for each drawer.
My AA batteries are estimate to have about 2500 mAh and the theoretical draw is 222 milliamps. Some simple math and I estimate that I can run the lights for roughly 10 continuous hours without replacing a battery (2500 mAh / 222mA = 10 Hours roughly). I used my multimeter to measure a few drawers and I found my consumption closer to 150 milliamps. Various light strips will be different so will different batteries but when I use tools my drawers are open only a few mins at a time so I expect the batteries to last a pretty long time.
Bottom line, battery packs are cheap and provide plenty of time running these lights. Moving on...
Step 4: Wiring and Testing
The wiring for this project is pretty straight forward. We are dealing with low voltage so any low voltage wire is fine. Big Box Stores sell low voltage 2 wire landscape wire which works great, or any other project wire you have will be fine too. I prefer solid core wire instead of braided wire for a few different reasons but the most important here is how easy it is to solder. The wire selection isn't that important do to the small length and low voltage. Your best friend at this step is testing, testing and retesting. Every time you solder something test for conductivity. Before you wrap anything up for good, make sure it works. Test, test and retest.
The wiring schematic might look scary but it's actually very simple. The battery pack has a V+ and V- (common, ground, neutral.... whatever you want to call it for this purpose). Those names for V- aren't truly interchangeable but for the purpose of this Instructable we can use them that way since the idea is that they are just for completing the circuit to the battery. I'm not a "sparky" (Electrical Engineer) so i'll let them point out the minutiae difference to me in the comments.
First, you need to measure the distance fro the desired location of the LED to the Switch. Measure along the inside of the perimeter wall of your drawer. You should be measuring where you want to run your wire and where it will be easier to hide it. You'll need to cut this much wire for each LED plus 1 - 2 inches for wire stripping and to make installation easy. Once you have those sections cut, strip the wire on each side.
One side of the wire should be soldered to the V+ and V- of the LED strip directly (note the picture of what this should look like). Make sure you note which wire is on the V+ and which is on the V-. It's helpful if the wire you use is two different colors or is someway marked. Do this for both LED segments for your drawer.
Cut some wire for running your battery pack from the switch all the way to the front of the drawer (straight down the middle of the drawer). The reason for this is to give you plenty of slack for replacing the batteries at some point in the future without disrupting anything. Solder the wire to your battery pack and note the V+ and V- connections.
Take the V+ wire from both LED's and the V+ wire from the battery pack and solder together.
Take the V- wire from the battery and solder on a female wire connector.
Take Both the V- from the LEDs and solder them together into a separate female wire connection.
At this point put batteries into the battery holder, and touch the two female connections together to test all soldered connections. Test, test and retest. You should get light, if you don't recheck all connections. Once you are satisfied with your pretty spectacular solder job, electrical tape (or heat shrink if your fancy) all solder exposed joints to prevent a short circuit or shock later. After this check for conductivity again, touch the V- sides together to complete the circuit and verify you didn't mess anything up.
Time to add some smarts to the light. Moving on to the magic in the tool chest.
Step 5: Don't Limit Yourself, Limit the Light
You may or may not know about micro / limit switches. You run into this switch all day long without realizing it. A typical application is to know if some movement has occurred. This could be your car door opening (to make the lights turn on), a position valve in power plant control, or any number of applications. This is the secret switch helping to automate all sorts of things. These switches are often used for their high reliability, quick switching and high tolerance precision for applications like ours here. This switch is the perfect application here for our tool chest. BTW, for more information check out this instructable about all types of limit switches and applications. If you don't care about more detailed information on the switch skip down to the bold part that talks about the using it.
There are 4 main parts to the switch we care about here: Rocker Arm, Common Leg, NC Leg and NO leg.
I'll start with the part where people are like what??!?!? NO and NC. This stands for Normally Open and Normally Closed, and while the name sounds weird is very descriptive of what it does.
Normally simply means the at rest position. If you put the switch on your table just sitting there doing nothing, that's the normal position. Closed is a Closed circuit and open is an open circuit. A closed circuit allows current to flow, an open one does not.
So when connected to the NC (Normally Closed) we have current flow without needing to do anything to the switch. When connected to the NO (Normally Open) we do not have current flow without doing something to the switch.
Rocker arm is the metal arm outside the red and black box that comes into contact with something moving. The movement of the arm is attached to the internal switch and changes the contact point internally from NC to NO. When the rocker arm is engaged the Limit Switch is no longer in the normal position. Understanding this operation isn't critical, just realize the arm moving change the contact point from NC to NO for the circuit.
Common leg is the portion of the switch that is always in the circuit. This leg should always be connected to a circuit.
OK done with the terminology explanation so lets not talk about how it works and instead how we'll use it. We will be connecting the V- from the battery to the Common leg of the Limit Switch with the female wire connector solder on during the last step. On the NC leg we will be connecting the V- from the LEDs wire connected soldered on during the last step. I took apart one of my switches for the purpose of this Instructable so you could see what is going on inside. You can see without the case on that there is a lever across the Limit Switch that connects to the NC without the rocker arm engaged, and pops over to the NO when the rocker arm is pressed. An internal spring resets the switch when the force to close is removed.
When we connect to the NC and COMM we have a complete circuit without the switch pressed. We use it this way because when the drawer is open, the pressure from the back wall is no longer on the switch, it goes back to its normal position (drawer open) and the light comes on. When we push the drawer closed, the limit switch makes contact with the back wall and opens the circuit disconnecting the lights from the power source.
Once you make this connection, you should again power up the battery compartment, and test the switch is working as expected: lights ON when nothing is pressed, and lights OFF when you squeeze the rocker arm closed. If you pass this quality step, move on to making the bracket for this guy!
Step 6: 3D Print a Bracket (3D Print Optional)
I know I know, most people are like I don't have a 3D printer, how am I going to do this?
Like I mentioned in the materials list if you don't have a 3D printer get some moldable plastic and make a bracket. I haven't used it before, I know many people who swear by this being a great alternative to an expensive 3D printer.
For those with a 3D printer the attached STL file will print 1 bracket, so print as many as you need. This project calls for 1 bracket per limit switch and the attached file works perfectly for the limit switches I call out in the materials as well as fit perfectly on a craftsman rear panel.
These brackets are pretty small and don't require a lot of material. I printed mine using the Windows 10 printing software with Medium Density and Medium resolution. Since they are pretty small, even a medium density gives plenty of strength.
The support that pushes into the limit switches are 3mm and can snap if even pressure isn't applied. (Sorry for switching back and forth between English and Metric but for the small stuff metric is better than fractions of an inch.) Push the limit switches firmly with equal pressure on both sides to avoid snapping a support. Make sure aligned properly so that the side with the switch extends over the edge towards the backside of the drawer. Refer to the attached picture for properly alignment so that you have good contact for the rocker arm to the rear panel of the cabinet frame. You should test fit with your particular cabinet so that when the drawer is fully seated, you have good contact with your limit switch to engage the rocker arm and close the switch. I'll load the design file as well as the print file so you can tweak it if you want.
This is a time to test and test and retest. Put your light package in your drawer (just place it in there) and affix the limit switch to where it's final position will be. With the drawer open the lights should be on, with it closed they should turn off. If all that works, continue on to final installation.
Step 7: Install Aka Use Tape to Hide Wires
My cabinet is black, so I used black duct tape so all wiring disappears. You can use any tape you want, I liked the clean look of Gorilla Black Duct tape.
Side not here, do you say Duct or Duck tape? I think both are correct, but when typing it up you realize that perhaps you use them interchangeable? The real funny thing is Duct tape was originally made for using on heating and cooling ducting (hence the name) but really shouldn't be used in hot attacks since the glue wears off and isn't really effective. Duck tape came from WW2 for use on Duck cloth, again hence the name. I think they are the same? End side note.
There isn't a wrong way to do this. Well, as long as you achieve the goal of securing and hiding the wires. If you tape your drawers closed, I would say that is a wrong way. You can look at my images for how I did it, but get creative here and put your mark on it. You do you here.
Tape from the light to the switch and make sure you leave the battery pack accessible. It's tape, probably over kill giving it its own step. Moving on.
Step 8: Final Product
First and Foremost I want to thank Edison and Oleg Losev. Without you guys this Instructable couldn't have been written.
We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light - Plato
Tada, light! Hopefully this project was easy enough to follow. This was my first of hopefully many Instructables, let me know how I did in the comments and share your pictures of you making this!