Oscilloscopes are very useful pieces of electronic equipment. They are perhaps most commonly seen in the form of an electrocardiogram (ECG) machine used in hospitals and clinics. The oscilloscope is a graph-displaying device - it plots a graph of an electrical signal. In most oscilloscopes, the graph shows how signals change over time: the vertical (Y) axis depicts the voltage and the horizontal (X) axis represents time. The intensity or brightness of the display is sometimes referred to as the 'Z' axis. Oscilloscopes are relatively simple but they provide lots of information about a signal. They can determine its time and voltage value, for example, and work out the frequency of an oscillating signal. Oscilloscopes also allow the moving parts of a circuit represented by the signal to be seen, and to discover if a malfunctioning component is distorting the signal. It is possible to discover how much of a signal is alternating current or direct current. Oscilloscopes can also determine how much of the signal is noise and if the noise changes over time. Distrelec supplies many types of oscilloscopes from manufacturers such as Keysight, PeakTech and Rohde & Schwarz. Analogue and digital oscilloscopes are available, as well as bench models and handheld portable devices, and related kit and accessories.