electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

, a continuity test is the checking of an

electric circuit An electrical network is an interconnection of electrical components (e.g., battery (electricity), batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e. ...

to see if

current Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (hydr ...

flows (that it is in fact a complete circuit). A continuity test is performed by placing a small voltage (wired in series with an

LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresp ...

or noise-producing component such as a

piezoelectric speaker A piezoelectric speaker (also known as a piezo bender due to its mode of operation, and sometimes colloquially called a "piezo", buzzer, crystal loudspeaker or beep speaker) is a loudspeaker that uses the piezoelectric effect for generating sou ...

) across the chosen path. If electron flow is inhibited by broken conductors, damaged components, or excessive resistance, the circuit is "open". Devices that can be used to perform continuity tests include

multimeter A multimeter (also known as a multi-tester, volt-ohm-milliammeter, volt-ohmmeter or VOM, avometer or ampere-volt-ohmmeter) is a measuring instrument that can measure multiple electrical properties. A typical multimeter can measure voltage, elec ...

s which measure current and specialized

continuity tester A continuity tester is an item of electronic test equipment, electrical test equipment used to determine if an electrical path can be established between two points; that is if an electrical circuit can be made. The circuit under test is complete ...

s which are cheaper, more basic devices, generally with a simple

light bulb Electric light is an artificial light source powered by electricity. Electric Light may also refer to: * Light fixture, a decorative enclosure for an electric light source * ''Electric Light'' (album), a 2018 album by James Bay * Electric Light ( ...

that lights up when current flows.

Uses

Continuity tests have uses which include testing components, ensuring proper grounding of equipment, and

reverse engineering Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompl ...

circuit boards.

Testing simple components

A continuity test can be used to test simple

electrical components An electronic component is any basic discrete electronic device or physical entity part of an Electronics, electronic system used to affect electrons or their associated electromagnetic field, fields. Electronic components are mostly industrial ...

like switches,

fuses Munitions, Fuse or FUSE may refer to: Devices * Fuse (electrical), a device used in electrical systems to protect against excessive current ** Fuse (automotive), a class of fuses for vehicles * Fuse (hydraulic), a device used in hydraulic systems ...

and wires. A working fuse, for example, should have continuity.

Grounding

Continuity tests are also helpful to determine whether an exposed electrical conductor is grounded. This can be done by placing one probe on the conductor in question, like a metallic

chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of a manufactured object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart ...

, and the other on a known

electrical ground In electrical engineering, ground or earth may be a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth. Electrical circuits may be co ...

point.

Reverse engineering

The continuity tester is also an important tool for reverse engineering

electrical circuits An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage so ...

and circuit boards, which means deducing its connections based on measurements and observation. In situations like construction work or electrical maintenance, one can test continuity on a bundle of electrical wires to find the two ends belonging to a particular one of these wires; there will be a negligible resistance between the "right" ends, and only between the "right" ends. In a similar fashion, on a

printed circuit board A printed circuit board (PCB), also called printed wiring board (PWB), is a Lamination, laminated sandwich structure of electrical conduction, conductive and Insulator (electricity), insulating layers, each with a pattern of traces, planes ...

, a continuity test between two solder points can give information on the traces connecting the components together.

Limitations

Since continuity testers work by attempting to close an electrical circuit, power must be disconnected before performing any continuity tests. Due to the presence of low-valued

resistors A resistor is a passive two-terminal electronic component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active e ...

motors An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gene ...

transformers ''Transformers'' is a media franchise produced by American toy company Hasbro and Japanese toy company Tomy, Takara Tomy. It primarily follows the heroic Autobots and the villainous Decepticons, two Extraterrestrials in fiction, alien robot fac ...

inductors An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when an electric current flows through it. An inductor typically consists of an insulated wire wound into a ...

speakers Speaker most commonly refers to: * Speaker, a person who produces speech * Loudspeaker, a device that produces sound ** Computer speakers Speaker, Speakers, or The Speaker may also refer to: Arts and entertainment * Speaker (song), "Speaker" ( ...

, and diodes in electrical circuits, continuity tests can give ambiguous information regarding how the circuit components are connected.

References

{{Reflist

External links

acmehowto.com
- continuity test Hardware testing