n Electronic Instruments Electronic Instruments Those instruments which

n Electronic Instruments

Electronic Instruments Ø Those instruments which employ electronic device for measuring various Electrical quantities (eg. Volt , current , resistance etc ) is known as electronic instruments. ØThere are large number of electronic instruments available for completion for various test and measurements.

voltmeter n A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit.

Oscilloscope n It display wave form signal. n An oscilloscope, previously called anoscillograph. n is a type of electronic test instrument that allows observation of constantly “continuously over a period of time; always. ”varying signal voltages,

n Oscilloscopes are used to observe the change of an electrical signal over time, such that voltage and time describe a shape which is continuously graphed against a calibrated scale.

Oscilloscope

ohmmeter n An ohmmeter is an electrical instrument that measures electrical resistance, the opposition to an electric current.

n Megaohmmeters measure large values of resistance. The unit of measurement for resistance is ohms (Ω). n A more accurate type of ohmmeter has an electronic circuit that passes a constant current (I) through the resistance, and another circuit that measures the voltage (V) across the resistance. According to the following equation, derived from Ohm's Law, the value of the

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What is the difference between Analog and Digital Multimeter? n Analog multimeters give the output as a reading on a scale against a pointer, while digital multimeter output is in numerical form displayed on a LCD.

Digital meter Analog meter

n Analog multimeters give a continuous output and carry a greater uncertainty in the measurement (about 3%), while digital multimeter measurements have a far less uncertainty (about 0. 5% or less). Digital multimeters are more accurate than analog multimeters.

n • Digital multimeters have a better range of measurements than analog multimeters. n • Digital multimeters offer additional features such as capacitance, temperature, frequency, sound level measurements and detection of semiconductor device pins (transistor / diode)

n Analog multimeters have to be calibrated manually, while most digital multimeters are calibrated automatically before every measurement. n • Analog multimeters have to be set for the specific range of measurement manually, while some must digital multimeters have auto ranging feature.

n Analog multimeters require practice to take good measurements, while digital multimeters can be operated even by an untrained person. n • Analog multimeters are less costly while digital multimeters are expensive.