The Learning Circuit 01: Circuit Basics with Cardboard Circuits

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If you've never created a circuit before then this is a great project to get started. All you need to make a basic circuit is some common materials and components. A circuit is a closed path through which an electric current can flow. A circuit can be closed or open. If the circuit is closed, all of the components are connected and the electrical current can flow. If the circuit is open, then the connection is broken and the electrical current cannot flow. Circuits are used to send energy to turn things on like the motor in a drill or a bulb in a flashlight. A lot of things you use everyday contain circuits and circuit boards.  A circuit board contains lots of little circuits that each have their own individual function.  One circuit might turn on a motor while another circuit might make a buzzer beep. You can make a simple circuit out of just a light bulb, a power source, and some wires.  To make this circuit, you’ll need some cardboard, some paper clips, some paper fasteners, a battery, some tape, and a light. It’s also useful to have a pair of needlenose pliers and a utility knife.

Circuits typically use wires and circuit traces to send electricity and signals along the circuit. In place of wires she uses paper clips and paper fasteners.  If you're going to do the same thing, it’s important to make sure that these items are metal and don’t have any coating. They need to be conductive so that electricity flows through them wherever they touch. For this project, a battery is used as the power source. Batteries have a positive and a negative terminal. Some components only work in one direction, so it’s important to note which orientation your battery is being hooked up.  This battery supplies 1.5 volts of power.  When choosing a light, you want to make sure you use one that is rated for low voltage. If the light is rated for 2 to 3 volts it should still work with one battery. First, Karen tapes down her battery.  She adds a paper clip to either side to act as the wires to conduct the electricity, as well as, acting as clips to help hold the battery in place.  She’ll use a pair of needlenose pliers to bend it in half, then put it right against the battery, and push a fastener right at the other end to help hold it snugly in place. Next, they’re going to add their light. The length of the paper clips is going to determine where this is going to go and if you need to you can add extra paper clips and fasteners to make sure that it reaches. She makes a loop of tape to put on the bottom of her light. Make sure that the screws of the light are facing out towards your paper clips so that it’s easy to reach. . She makes a loop of tape to put on the bottom of her light.  With the last paperclips, loop around the screws of the light socket and then connect the ends over to your other paper clips and secure them with a fastener. If you have everything hooked up correctly your light should be on.  If your light is not on then check all of your connections, make sure metal stays touching metal when not being held, make sure you are using a fresh battery, check inside the bulb, and make sure your bulb is screwed all the way in.  Karen gives her method for battery testing without tools and suggests making sure the filament inside the bulb is not broken.  If the filament is broken then it turns this into an open circuit because electricity cannot flow across it.

For this project, Karen prefers to use incandescent bulbs because they are less sensitive to voltages. She also goes over what you need to look for in LEDs if you want to use those for this project. Karen gives you what you need to know if you want to use LEDs for this project instead.  LEDs come in different sizes such as a 3 millimeter, a 5 millimeter, and a 10 millimeter LED. LEDs are more sensitive to voltages than incandescent bulbs. With incandescent bulbs, orientation in the circuit doesn’t matter. LED stands for light emitting diode.  A diode is an electrical component that only lets electricity flow through it in one direction. An LED will not work if it is hooked up backwards. You can identify the negative side of an LED a few different ways.  Usually the negative lead is shorter, and if you look inside the LED the larger side is the negative side. The last thing Karen shows you is how to make a switch with your circuit. You can loosen one of the paper clips so that it just touches the top of the fastener.  This allows it to swivel and easily open and close to become a switch, open and closing the circuit. A line and circle on some switches represents a closed or an open circuit. When the switch is positioned to the o side that represents an open circuit and its off. When the switch is positioned to the line side that represents a closed circuit and the switch is on.