Instruments and machines should be tested immediately after manufacturing or in the later stages of the product lifecycle to ensure that their functioning and performance conforms to the industry standards and are properly calibrated. This testing is done by electronic test equipment which captures responses to its signals produced by the instrument under testing (device under test, DUT). The electronic parameters measured by the test equipment include electric current, resistance, capacitance, inductance, voltage etc.
From simple handheld devices to sophisticated lab equipment
An example of the simplest electronic test equipment is a tester consisting of a metal end/test lead and a light bulb which is used to check the presence of electric voltage in a device. Among the most advanced test equipment is the automatic or automated test equipment (ATE) such as digital multimeters and Keithley instruments.
Simple equipment for basic testing in an electronic circuit
The most widely used ones are:
Voltmeter: Measures the voltage or electric potential difference between two different points in a closed or open electric circuit. An example is the Weston Cell. Voltmeters can be analog or digital and are represented as V in the circuit diagram.
Ammeter: Measures the current in a circuit in terms of Amperes, mill amperes or microamperes. The most common example is the galvanometer, and the modern meter is called as D’Arsonval/Weston type galvanometer.
Ohmmeter: Measures electrical resistance in ohms. There are microhmmeters and megohmmeters.
Multimeter: Measures multiple parameters such as voltage, current and resistance, and hence also called as VOM (Volt-Ohm-Milliammeter). Multimeters can be analog (value displayed by a pointer) or digital (numeric display).
RLC meter: Measures the three fundamental components of electronics, namely, resistance, inductance (inducing electromotive force or EMF) and capacitance (stores an electric charge).
To provide stimulus (usually electric energy, electronic signals) to an electronic circuit for the purpose of testing, stimulus generators are used. The different types of generators are signal generators, pulse generators, digital pattern generators, function generators (analog circuits) and power supplies.