The major components in any basic circuit include a breadboard, a power source (a battery), resistors, wires, ammeters and voltmeters. As circuits get more and more complex, you begin using components such as capacitors, transistors and switches. All of these components will be explained in this page.
A breadboard is simply a board in which you plug your components into when making a circuit. It is usually a plastic board with holes in it. These holes are connected (inside the board) by metal which allows the current to flow through the components. All holes in the same horizontal line are connected together. Running in a vertical line somewhere on the breadboard are called "buses." These are usually where you would plug your power source and your "ground" into.
Every circuit requires some sort of power source. This is usually in the form of a battery. The symbol for the battery on a schematic diagram is . If using a regular battery, you will need to solder wires onto the + and - terminals of the battery. Then you may plug these wires into the breadboard. The battery is a type of capacitor with charge stored up on one side (plate). When connected to something else, current will flow.
Resistance controls the amount of current that flows through the circuit. A high resistance allows only a little current to flow and inversely, a low resistance will allow a lot of current to flow. For example, air has a very high resistance and therefore current rarely will flow through it. Lightening though, is an example of current flowing though air. The component of resistance is the resistor. Each resistor has a determined value of resistance that is indicated by the color code on it. These factors include Resisitance is measured in ohms ( ). The symbol for a resistor is .
There are also variable resistors called potentiometers or pots for short. These pots have a range of resistence. Depending on where the dial on the pot's head is, there is a different resistance value. An simple example of a pot in action is the volume control on most stereos. Turning the dial clockwise will decrease resistance and increase volume and vice-versa. The value given to the pot is at it's highest resistance. The symbol for a potentiometer is .
Metals have a very low resistance and therefore wires are made of out of metals. They allow for the connecting of components with minimal resistance.Wires are usually covered in plastic (or rubber) to prevent two wires from touching and creating a short circuit (infinite current).
An ammeter is a device to measure current. It is always placed in series in a circuit. Amp measurements are usually very low, in the milli or microamp categories. One amp is enough to kill you, so be VERY careful. If you are interested in safety issues, see our safety page. The symbol of an ammeter is .
A voltmeter is a device to measure voltage. It is always placed in parallel in a circuit. The symbol of a voltmeter is .
A capacitor's primary uses include storing charge and blocking the flow of direct current while allowing alternating curent to flow. Capacitance is equal to the charge on either plate (q) / voltage (V) and is measured in farads (F). The symbol of a capacitor is . Capacitance is further discussed on page 4 of the tutorial.
Transistors are devices which amplify a change in current. They contain two semiconductors; one sandwhich between two layers of the other.
In circuits, switches are to used complete or break a path for which current to flow through. There are several type of switches used in circuits. , is a single pole single throw (spst) switch. This is a two positions switch (on, off). It is capable of making or breaking a circuit in only one point. , is a single pole double throw (spdt) switch. The connection can be made in two places on this switch, the pole will "make" the circuit if it is on either the top or bottom contact. It will break the circuit if it is in the center. There are many other switches with variations attached to them.