There are a variety of common components used in electronic circuits, all which every electronics hobbyists should be able to identify. Of course, if you're working on a specialised projects, the components you use may be slightly different from the norm, but there are a few common ones that can be easily identified. Read on to learn how to identify electronic components.
Note the shape, colour, material and any numbers on the component you're trying to identify. These can be useful not only in finding the type of component but also in locating the component's properties or manufacturer. Also, pay close attention to any series of coloured bands on the component.
Count the number of pins on the component. Two-lead components are most common--there are only a few types of components that can have three or more pins.
Determine the type of component.
Identify resistors, the component that decreases the amount of conductivity in a path. Resistors are used to limit current or as a voltage divider to provide a lower voltage than the supplied voltage to a component. The coloured bands on a resistor define the resistance value in ohms.
Look for components that look like little cans with leads coming from the bottom and you've found electrolytic capacitors. They can range in size from about the size of a resistor to the size of your forearm, though the physical size has little to do with the actual capacitance. A physically large capacitor may be low capacitance, but able to operate at very high voltages. Their value (usually in microfarads) will be printed on the body of the capacitor.
Note capacitors that look like small discs and are of much smaller capacitance than electrolytic capacitors. These are ceramic or mylar capacitors. These types of capacitors are used more often in timing and coupling circuits. Their value is represented as three-letter code printed on the body of the capacitor and is normally in picofarads.
Find components used for illumination or indicator lights and you've located light emitting diodes. These are small, coloured and translucent components that are like little light bulbs. When supplied with current, they'll light up.
Consider that a component is likely to be a transistor if it has three pins, as it's one of the only components with three pins. They type of the transistor can be determined by the model number, which is printed on the body of the component.
Examine diodes. A diode is typically a black component with two leads and a white stripe. A diode with a clear body and copper-coloured interior is usually a zener diode. A diode is used to limit the direction of current to one direction and is normally used in power regulation circuits or communications circuits.
Differentiate amongst types of switches. Switches can come in a variety of shapes and sizes. A rocker switch is a typical on/off switch, but there are also a number of pushbutton and slider switches to be found on electronic circuits. Switches often don't have model or manufacturer numbers, so to determine the exact type of switch you may need to use a multimeter.
Think of "chips" by their real name--integrated circuits. They're usually black and have eight or more pins. Their function can be determined by the model number printed on the top. For exact specifications, find a datasheet from the manufacturers website or datasheet databases such as AllDataSheet. See the Resources section below for a link.
Identify a variable resistor with three legs as a potentiometers. A potentiometer will normally be a small box or round shape, but also are often in the form of a knob, like that you might find on a radio. The value is often printed on the component but if it is not, it can easily be determined by measuring the resistance between the two outer pins with a multimeter.
Be aware that electrolytic capacitors are polarised, they cannot be inserted into a circuit backwards or they may explode.