resistor

Resistors "resist" the flow of electrical current. The higher the value of resistance (measured in ohms) the lower the current will be. 

Go to an online resistor calculator. Identify the value of your resistor by its color bands.

capacitor

In a way, a capacitor is a little like a battery. Although they work in completely different ways, capacitors and batteries both store electrical energy. 

The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate. A capacitor stores energy in the electric field between a pair of conductors (called "plates").

light-emitting diode (LED)

A light-emitting diode (LED) is a semiconductor 

diode that emits light when connected in a circuit.

More on LEDs here.

Visit the LED calculator to determine which resistor to use for your LED project.

Most standard resistors are 2 volts 20 mA.

signal diode

Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve and early diodes were actually called valves.

Diodes must be connected the correct way round, the diagram may be labelled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode!). The cathode is marked by a line painted on the body. Diodes are labelled with their code in small print, you may need a magnifying glass to read this on small signal diodes!

transistor

TThe design of a transistor allows it to function as an amplifier or a switch. This is accomplished by using a small amount of electricity to control a gate on a much larger supply of electricity, much like turning a valve to control a supply of water. 

Transistors are composed of three parts – a base, a collector, and an emitter. The base is the gate controller device for the larger electrical supply. The collector is the larger electrical supply, and the emitter is the outlet for that supply. By sending varying levels of current from the base, the amount of current flowing through the gate from the collector may be regulated. In this way, a very small amount of current may be used to control a large amount of current, as in an amplifier. The same process is used to create the binary code for the digital processors but in this case a voltage threshold of five volts is needed to open the collector gate. In this way, the transistor is being used as a switch with a binary function: five volts – ON, less than five volts – OFF. 

dc motor

See more simple diagrams of how a dc motor operates here. 

stepper motor

A stepper motor is a motor controlled by a series of electromagnetic coils. The center shaft has a series of magnets mounted on it, and the coils surrounding the shaft are alternately given current or not, creating magnetic fields which repulse or attract the magnets on the shaft, causing the motor to rotate. See this page for a detailed explanation of the difference between a unipolar and a bipolar stepper motor.

coming soon...

555 timer