Build a portable, fun and easy to make basic LED circuit that works! No soldering is needed.
Also, learn about electricity and electrical components by building the LED Creepy Creature.
What you can do with your LED Creepy Creature
· Tickle the switch area and the LEDs will blink on and off.
· Place your fingers under the cloth and use as a puppet.
· Use to find your way in a dark room.
· Use with a friend who has one to communicate with a secret code.
· Entertain your friends and relatives of all ages.
· Impress your friends and relatives by telling them that you made it and tell them how it works!
Tell them how photons shoot out of the LED Creature eyes!
Step 1: Part List
Step 2: Pattern
Cut out the paper pattern and trace it around the hanging file folder material. Cut out the folder material and punch out two small holes for the eyes.
Note: The pattern on the PDF may be larger than the one I used. The size should be about 2.25 wide by 5.25 inches long.
Step 3: Insert the LEDs
Insert one LED’s into each hole. They should fit tight. With the terminal pins (legs) facing you, examine and notice that each LED has one leg that is slightly longer than the other. Align each LED so that the two long legs are on one side facing the bottom of the pattern. Twist the pair of long legs together and then the pair of short legs. Test the LEDs by holding the battery between the long and short legs with the plus side of the battery contacting the long legs. The LEDs should light up. Bend over the short legs towards the head and the long legs towards the bottom.
Step 4: Battery Assembly
Wrap a very narrow strip of scotch tape all the way around the outer edge of the battery. Cut 2 pieces of aluminum foil about 1” wide by 3½” long. Fold the foil strips in half lengthwise and smooth the foil out with your finger. Using clear shipping tape, tape the end of one strip of foil to the + side of the battery and the second foil strip to the other side of the battery as shown onin the Figure. Press the tape hard to secure the tape and foil to the battery.
Step 5: Foil Strips
Place the battery/foil assembly with the flat (battery plus end) down onto the pattern (circuit board) as shown on the Figure. One foil strip should reach the long set of LEDs legs and the other foil strip is wrapped around to the other side of the pattern. Tape the foil to hold it in place. Do not tape the foil on the LED light side.
Step 6: Making a Switch
Using the hanging file material cut a small rectangular strip about the size of a stick of gum. Cut another piece of foil 1” wide by 5½”long. Wrap one end around the gum stick foil material and tape the side that was folded over. With the side you just taped, bend up the end of gum stick foil about 1 inch from the end. Tape the strip so that the bent end is on top of, but not touching, the foil piece connected around to the battery as shown on the Figure.
Step 7: Connecting the Foil to the LEDs
Bring the foil from the front side over the top of the head to the short LEDs legs on the back side. Wrap the foil under and over the short LED legs and secure with clear shipping tape. Do the same with the long LED legs.
Test the circuit by pushing down the foil switch. The LEDs should light up.
Step 8: Add Cloth
Step 9: To Do and Notice
Close the switch by pushing down on the tab. The LEDs should light. If not, make sure all the connections are tight and the LEDs legs and battery are connected properly. LEDs are a semiconducting device which means they conduct current or electrons in one direction only. Therefore the + side of the battery must be connected to the long leg (anode) of the LED. If not, the LED will not work. Normally you will see a resistor in series with a LED to reduce the current flow and to protect the LED. The battery used in LED Creepy Creature circuit is too small to damage the LED. However, you could add one resistor to the circuit to reduce the brightness of the bulb.
Step 10: The Science Behind the Activity
Electrons are found in, essentially, all things. Objects made of metal have many, many electrons that can easily move within the object and from one metal object to another. Conductors are items, like the metal in wires, which can provide a path for electrons to bump along, a little like falling dominoes. Wires are often covered with an insulator, a non-conducting material that does not allow electrons to move through it easily. The electrons move inside the wires and not through the insulation surrounding the wires.
Batteries have three parts: an anode, a cathode and the electrolyte. The cathode and anode (the positive and negative sides at either end of a traditional battery) are hooked up to an electrical circuit. The chemical reactions in the battery cause a build-up of electrons at the anode. This results in an electrical difference between the anode and the cathode. You can think of this difference as an unstable build-up of the electrons. The electrons want to rearrange themselves to get rid of this difference. But they do this in a certain way. Electrons repel each other and try to go to a place with fewer electrons. In a battery, the only place to go is to the cathode. But, the electrolyte keeps the electrons from going straight from the anode to the cathode within the battery. When the circuit is closed (a wire connects the cathode and the anode) the electrons will be able to get to the cathode. In the LEDCreepyCreaturecircuit, the electrons leave the battery, go through the aluminum wire and switch, lighting the LEDs along the way and return to the battery. This is one way of describing how electrical potential causes electrons to flow through the circuit.
In a circuit, the power source is connected to some type of resistive load or object being powered, such as a light, motor, or electromagnet. An open circuit has no current (electron “flow”) because of a gap or opening somewhere in the path of conductive material from the power source to the load and back to the power source. A circuit that has no gaps is called a closed or complete circuit. Electrons act as if they are lazy and want to take the shortest path, electrically, back to the battery instead of going to “work” in the light bulb, motor, or other high-resistive load. When a low-resistive path occurs that bypasses the high- resistive load, the circuit is said to have a short circuit. A short circuit can cause wires and some batteries to heat up until burning hot! The small button cell used in the LEDCreepyCreature circuit is too small to ever get hot even during a short. However, a short circuit will “drain” the battery by quickly converting the stored chemical energy into electrical energy. Adding the narrow strip of tape around the button cell battery prevents the foil strips connected at the battery from a short circuit.
Step 11: How LEDs Work
Light emitting diodes, commonly called LEDs are a semiconductor diode. It consists of a chip of semiconducting material treated to create a structure called a p-n (positive-negative) junction. When connected to a power source, current flows from the p-side or anode to the n-side, or cathode, but not in the reverse direction. Charge-carriers (electrons and electron holes) flow into the junction from electrodes. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon (light).
Step 12: LED Advantages
While all diodes release light, most don't do it very effectively. In an ordinary diode, the semiconductor material itself ends up absorbing a lot of the light energy. LEDs are specially constructed to release a large number of photons outward. Additionally, they are housed in a plastic bulb that concentrates the light in a particular direction. As you can see in the diagram, most of the light from the diode bounces off the sides of the bulb, traveling on through the rounded end.
LEDs have several advantages over conventional incandescent lamps. For one thing, they don't have a filament that will burn out, so they last much longer. Additionally, their small plastic bulb makes them a lot more durable. They also fit more easily into modern electronic circuits.
But the main advantage is efficiency. In conventional incandescent bulbs, the light-production process involves generating a lot of heat (the filament must be warmed). This is completely wasted energy, unless you're using the lamp as a heater, because a huge portion of the available electricity isn't going toward producing visible light. LEDs generate very little heat, relatively speaking. A much higher percentage of the electrical power is going directly to generating light, which cuts down on the electricity demands considerably.
Up until recently, LEDs were too expensive to use for most lighting applications because they're built around advanced semiconductor material. The price of semiconductor devices has plummeted over the past decade, however, making LEDs a more cost-effective lighting option for a wide range of situations. While they may be more expensive than incandescent lights up front, their lower cost in the long run can make them a better buy. In the future, they will play an even bigger role in the world of technology.