University:
Miami Dade College
Course:
EET1082 | Introduction to Electronics
Academic year:

2023
Views:

350

Pages:

4
Author:

Ryker Galvan

Introduction to Electronics: Chapter 6 (Electrical Measurements- Meters) Introduction to Meters Analog Meter - Uses a graduated scale with a pointer. Digital Meter - Provides a reading in numbers. - More accurate than analog meters. The placement of an ammeter in a circuit. (A) Schematic symbol of voltmeter. (B) A voltmeter is connected in parallel in a circuit. (A) Schematic symbol of an ohmmeter. (B) An ohmmeter applies a voltage across the component being measured and monitors the current flowing through it. Multimeters Multimeter - Combines a voltmeter, ammeter, and ohmmeter into one package. VOM (volt-ohm-milliammeter) - An analog multimeter that measures volts, ohms, milliamperes. DMM - A digital multimeter. An analog multimeter. Advantages of DMMs over VOMs: - Easier readability, resulting in a higher accuracy with smaller voltage. - Auto ranging capabilities. - Autozeroing for resistance reading. - Auto lock of a displayed value. Disadvantages of a DMM - Requirement for a source of electricity. - Voltage limitation. - Inability to measure an instantaneous change in a signal faster than the sampling time. An ammeter is connected in a series to a circuit. An ammeter is one part of this VOM. A black negative lead plugs into the common or negative hack. A red positive lead plugs into the jack with plus symbol. Caution: - Always turn off power before connecting an ammeter to a circuit. - An analog ammeter must never be connected in parallel. - Never connect an ammeter directly to a voltage source. When connecting a voltmeter to a circuit, be sure to observe polarity. Caution: if an analog voltmeter is connected in series with a circuit, a large current can flow through the meter and might cause damage to the device. When using ohmmeter to measure resistance, the component being measured must be removed from the circuit. Continuity test (or check) - Determines if current path is continuous. - Open circuit. -Indicates high resistance. - Short circuit -Zero ohms of resistance. - Closed circuit -indicates low resistance. Reading meter scales: Full Scale Value: - Maximum value indicated by a meter. Ammeters and voltmeters: - Read from left to right. - Linear scales. Ohmmeters: - Read from right to left. - Nonlinear scales. Summary: - Analog meters use a graduated scale with a pointer. - Digital meters provide a direct readout. - A multimeter combines a voltmeter, ammeter, and ohmmeter into one package. - A VOM is an analog multimeter. - A DMM is a digital multimeter. - On a multimeter, the range selector switch selects the function to be used. - An ammeter must be connected in series with a circuit. - A voltmeter is connected in parallel with a circuit. - An ohmmeter measures resistance by applying a known voltage.

Introduction to Electronics Chapter 6 Notes

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