(AET) Study Guide - NCATT

Page 11 of 51• Multimeter—Multi-function meter used to test current values, voltage values, or ohmicvalues (resistance). With the flip of a switch, a multimeter can be set up as an ammeter,voltmeter, or ohmmeter. Displays on a multimeter are provided in both analog and digitalformat. Use a multimeter whenever possible.• Ammeters—Electrical testing instrument used to measure the amount of current flowingthrough a load. Values are given in amps. Some ammeters measure milliamps andmicroamps.• Voltmeters—Electrical testing instrument used to measure electrical voltage acrosscomponents. Values are given in volts. Use a voltmeter for measurements andcalculations to find a probable defect.• Ohmmeters—Electrical testing instrument used to measure resistance in a circuit orcomponent. Values are given in ohms. An ohmmeter provides an effective and quick wayto test the condition of a switch.• Oscilloscopes—Electronic test instrument that displays the waveforms of electricalsignals. Oscilloscopes measure voltages (AC peak-to-peak values), measure time todetermine frequencies, and display phase relationships (comparisons of waveforms intime) to identify equipment malfunctions.4. Resistors NCATT Training Standard Level (A)(a) Color CodesObjective:Identify basic facts and terms about resistor identification (values) using color codes.Content – Color Codes:Explain three methods for finding a resistor’s value. The following methods are acceptable to finda resistor’s value.• Refer to a schematic diagram where the value of the resistor is printed.• Measure the individual resistor with an ohmmeter.• Read the value (color code band) from the resistor itself, if it is legible.Optional - Explain how the mnemonic, “Big Bears Romp On Yellow Grass But Violets GrowWithout Getting Stomped Good Story? – “Not!”, to assist students in reading the color codebands.Big - Black - 0Bears - Brown - 1Romp - Red - 2On - Orange - 3Yellow - Yellow - 4Grass - Green - 5But - Blue - 6Violets - Violet - 7Grow - Gray - 8Without - White - 9Getting - Gold - 0.1Stomped - Silver - 0.01Good - Gold - ± 5%Story - Silver - ± 10%Not - no Color - ± 20%Copyright © 2008 by the National Center for Aircraft Technician Training. All rights reserved.Individuals may download, print, and make copies of this documentfor their own personal use. Commercial use prohibited.