multitester

A multitester, commonly known as a multimeter, is a handheld instrument used to measure electrical parameters. In common usage, it is equivalent to a multimeter and consists of multiple measurement functions in one device. A typical multitester can measure DC and AC voltage, DC current, and resistance. Most models also offer continuity checks, diode tests, and may include additional functions such as capacitance, frequency, temperature, and transistor testing.

Design and operation: A multitester has a case with input jacks, one or more probes, and a selection dial or menu. Digital multimeters use an LCD readout; analog models use a needle display. Auto-ranging digital meters automatically select the correct scale, while manual-range meters require the user to choose the range. To measure, the user connects the probes to the circuit under test according to the function and range, then reads the result. For current measurements, some meters require breaking the circuit; clamp meters measure current without contact by using a magnetic core.

Safety: Multitesters are designed for low- to medium-energy electrical work. They carry safety ratings (for example CAT II, CAT III, etc.) that indicate acceptable test environments. Users should observe proper handling, use appropriate input jacks, keep fingers away from live circuits, and never exceed the device's specification.

Applications and limitations: Used by electronics hobbyists, technicians, electricians, and automotive professionals to troubleshoot circuits, verify components, and test power supplies. The accuracy depends on range, input impedance, and calibration. They are not suitable for high-energy power systems without proper equipment and procedures.

History: The multitester evolved from separate voltmeters, ammeters, and ohmmeters. The term is sometimes used interchangeably with digital multimeter; modern devices are predominantly digital and often auto-ranging.