City lights is a fun project for kids of all ages to begin to learn a bit about soft circuits and an opportunity to create a fun at home project based either on your home city or one in your imagination. You will build simple block style buildings integrating LEDs for visual fun, there is a simple and a modular version so the sky is the limit with what you can create!

Step 1: Before We Begin

- 1 large Foam Core (for the building bases)
- 1 large artboard
- 10 LEDs various colors (one for each building so get as many as you want)
- 10 330 -ohm resistors (or as many LEDs as you get as you use one for each)
- 20 small Neodymium magnets (i reccomend these: https://www.kjmagnetics.com/proddetail.asp?prod=B441)
- 1 roll of copper tape (you will not use all of it)
-double sided tape
- hot glue gun or glue dots
- Sheets of tracing paper or vellum (for the buildings)
- 2 metallic sheets 26' guage or thinnner (you can even remove one from one of those little fridge magnet boards) 
- Soldering iron
-Scissors or exacto knife
- 2 9v batteries
-2 9v battery connectors 

(if you dont know how to solder yet check out this tutorial https://www.instructables.com/id/How-to-solder/)
kids of all ages should learn to solder and work responsibly, the earlier the better

all of these materials are available at your local art store or staples and radio shack, but i would recommend buying some of the electronics parts with special attention to the magnets online as the price differences are remarkable.

Step 2: The Base

Its best to just dive right in, so we will begin with the base that will hold and provide current to all of the buildings.

While the dimensions of your base can be whatever you want this example is constructed around one that is 8.5" x 11" (or basic letter paper size).

You want to place the sheet of metal in between two of art board, gluing it firmly in place. This allows the magnets in the buildings to easily attach and hold to the base, while also insulating it from the current that will be going through the copper tape. As you all may know the metal sheet is highly conductive so not doing this would render our project rather ineffective.

Step 3: Power Lines

In terms of a city we are going to place the copper tape in the form of power lines across our base.

Begin by running the lines in pairs (one for positive and one for negative current) across the base. Remember to leave a little bit of each hanging over the edges for we are going to connect them on the back. I left 3/4 inch of space in between each line (this will be important for where we place the magnets in our buildings).

For this example this will give us 4 rows of places to put your buildings.

Step 4: Connecting Our Roads

Dividing our board in half we are going to connect two positive and two negative lines together in parallel and then to each of our power sources (9v batteries).

The easiest way to do this is to connect the lines in a simple C shape, to which we will later attach the lines of our battery connectors.
VERY IMPORTANT that the lines do not touch each other, as you can see i placed a piece of electrical tape where one line crosses over the other, this will insulate the positive from the negative current.

Then placing the battery in the center of the base line up your positive (red) power line and your negative (black) power line to each of the copper tape roads. 

Step 5: Soldering Points

At times simply placing copper tape together will not be enough for the current to pass through appropriately, the best practice is to place solder dots at all of your joints.
At this point you are also going to want to solder the battery connector wires to their respective positions on the copper tape.
This will effectively power that half of the board!

Step 6: Repeat for Other Side

Repeat steps 4 and 5 for your other two roads. To keep things simple and separated i did them on opposite sides of the board. 
This step finishes of our board so we can now begin to make our buildings!

Step 7: Building Base

Cut the foamcore into a 1 1/2 inch square, this will serve as the base for the building. Then place a glue dot or a dab of hot glue in the center. This will be there to hold the LED in place. 
Take you LED and bend its legs out flat, remember electricity can only flow one way through an LED so making note of the positive side is important (this is the long leg or anode, the short leg is known as a cathode), i find it best to mark this right on the base so as not to forget.

Step 8: Resistors

Next we want to clip the legs of the led to make room for our resistor. 

For a bit of background, we are including a resistor because the LEDs (5mm) in this case are not meant to be connected directly to a 9v battery, this would cause them to burn out almost instantly (one flash and a pop and a dead LED is all you will be left with). So a resistor is used (330-ohm) in this case to lower the current that is passed to the LED.

Clip the resistors legs as well and place it on the positive side of the LED, using again a glue dot or hot glue dab.

Step 9: Magnets

On the bottom of the base place the magnets, approx. 3/4 inch apart (same distance as in-between our power lines). Make sure they are in line with the positive and negative sides of your LED.

These magnets are what will allow the current to pass from the board up to the led (they will be connected with copper tape in the next step) as well as what allow the buildings to stick to the base, making them much sturdier and you wont have to worry about simple movements knocking the lights off. 

Step 10: Connecting the Lights

now you want to run a piece of tape (one from the negative leg of the LED and the other from the free leg of the resistor) down and over the magnets below. These will allow the current to flow up and turn on the light.

Step 11: Solder Connections and TEST

As before to have strong connections we want to solder all of our open points between the light the resistor and the tape. In this case there are 3 points, the resistor to the positive copper tape, the resistor to the anode(positive) side of the LED, and the cathode (negative) side of the LED to the negative stripe of copper tape.

Once you connect these you can test our you light  by simply placing it on your base (remember which line is positive and negative) and it should light up. One good thing about the LED is that if you hook it up backwards (or place it backwards) nothing will happen (no frying) so if it doesn't light up you just have to spin it around!

Step 12: Build Up the Walls

Now we are going to create the rest of the building that will be lit up by the base we just created, now while this can take any shape that you want for the purposes of simplicity these are the designs for a cube.

You ar going to have 4 sides and a lid for your building, so in this case working off a 1 1/2 inch base, we will have 4 squares of that equal length and a lid drawn above one of them.

Remember to account for flaps to make the lid and sides stick together better!

Step 13: Simple Box Complete!

Now you can chose to simply fold along your lines and create a basic cube building which will have an end result like that shown below, or you can follow the next few steps to make a modular building (stackable) to increase the variety of your buildings!

To get what is featured below simple apply double side tape to the bottom edge of the cube, as well as the 3 flaps on the lid, and paste it around the base light that you created before!

Step 14: Modular Building

If you want to continue and make building blocks that can be stacked on top of eachother, stop after folding your paper frame and follow the next steps:

The way we make them modular (stackable) is by extending the power running through the light (both positive and negative lines) to the lid, and include a small piece of metal in the lid, allowing the magnets to create that same strong hold they have to the base.

so first cut out a square of metal the same size of your lid (depending on what thickness of metal you are using simple scissors may not be enough, luckly metal sheers are very easy to come by at any home depot, they look just like scissors just alot thicker).

Then using your double sided tape attach just one side to our light base.

Step 15: Extend the Lines

Starting with our positive side place a small section of copper tape to run up the side of the building, touching the tape that comes up from the magnet below. 
Leave a little bit as a flap for above which we will later extend.

Than you want to make another solder dot here to connect the two pieces of tape.

Step 16: Repeat

now you want to repeat the previous step for the negative line to go up the opposite side.

Step 17: Close the Lid and Build the Roof

Now you are ready to close of the box just like you did with the simple building, while leaving the two little copper tape flaps extended above.

Once your lid is closed and in place, bend these down in order to extend them.
You want to keep the same distance as before (3/4 inch) between the two strips so any of the buildings you make can easily attach!

One final step for good practice will be to solder the tape connections on top, this will provide us with a fool proof connection.

Step 18: Finished!

now using either of the two building styles make a bunch of them, with all of your different LEDs!

Even begin to make taller buildings, both by stacking and by designing longer frames with your tracing paper!!!

Hope you all enjoyed, and feel free to post your own customized creations!!!!
love it..very cozy
An exellent Instructible! I especially like the attention to detail in the layout of the power lines and how you are connecting them. One suggestion, if I may - I would suggest adding a bit more detail in the discussion concerning connecting the resistor to the LED. Why would the LED fry when 9v is applied? How do you know this? How do you know the resistor you've chosen is correct? <br> <br>These are very basic questions with very simple and direct answers, but they also could have deadly consequences in circuits rated differently for power. I would never assume your reader has the fundamental background in electronics to know the answer to these questions - especially with an 'able that will certainly inspire young larval makers to attempt ;-)
It is easy..white, green, and blue work with 3.0 volts DC..red and yellow use 2.0 volts DC..To find the resistor value, subtract the needed voltage from the beginning voltage and divide by .020..This is not exact but it works..Remember that the polarity must be right..A round LED has a flat on one side..This is negative(-) side..Hooking up reversed does no harm as long as the voltage drop is correct..It just will not light up..
Hello to you and your team in Minnesota,<br><br>Unfortunately our two projects are not related, perhaps by a coincidental although corny name on my part, but other than that they share nothing. This was a project created in class at our soft circuits workshop, with no research or precedents even looked up, and until receiving this note from you, i personally had never heard of your work or program. Not that this reflects on the quality of your work, which is nice, and i agree that everyone should have access to everything being created and that students should be proud of their work; but this was a project developed on the ideals of getting young children interested in circuitry while at the same time giving it a creative narrative which is where the city came into play, not just giving children another toy that they cannot manufacture themselves. As a creative individual myself i can understand frustration when a project is not deemed unique, but one must always remember that it is not always the idea that is worthy of recognition rather your process an the end product it creates. Instuctables.com in and of itself remains a community for sharing knowledge and creativity, not accusations and personal recognition. <br><br>Sincerely, <br>Made_by_kyle
Very cool! <br>One suggestion I would make is too put two LED's in, (one reversed).. This way the blocks would always light up, but depending on the LED's inside may even change color.. <br>
very nice instructable, brilliant idea...
nice job

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