LAB SCOPESLAB SCOPES
HIGH SPEED VOLTMETERHIGH SPEED VOLTMETER
Replaces:Replaces:• Test LightTest Light• Digital Voltmeter/Ammeter/OhmmeterDigital Voltmeter/Ammeter/Ohmmeter• Frequency MeterFrequency Meter• Duty Cycle MeterDuty Cycle Meter
Types Of OscilloscopesTypes Of Oscilloscopes
Analog:Analog:• Real Time (Direct Reading of signal)Real Time (Direct Reading of signal)• No memoryNo memory
Digital: Digital: • (LCD or Cathode Ray Tube)(LCD or Cathode Ray Tube)• Uses a memoryUses a memory• Delayed to screen (need high sampling rate)Delayed to screen (need high sampling rate)• Cursor movementCursor movement
VOLTAGE OVER TIMEVOLTAGE OVER TIME
Scopes measure Voltage Scopes measure Voltage and Timeand Time DVOM’s measure average of pulsing DVOM’s measure average of pulsing
voltagevoltage Vertical movement - voltage change Vertical movement - voltage change
over timeover time Horizontal movement - Time it takes for Horizontal movement - Time it takes for
voltage changes to occur.voltage changes to occur.
SCOPE SCREEN SCOPE SCREEN
Divided into small sectionsDivided into small sections Grids or GraticulesGrids or Graticules 10 grid X 10 grid Screen10 grid X 10 grid Screen Voltage level between grids is Voltage level between grids is
adjustableadjustable Time base between grids is adjustableTime base between grids is adjustable
ADJUSTING SCOPEADJUSTING SCOPE
Largest waveform Largest waveform 2 or 3 complete cycles2 or 3 complete cycles Voltage range with one grid above max. Voltage range with one grid above max.
volts and one grid below min. volts.volts and one grid below min. volts. Trigger LevelTrigger Level Trigger SlopeTrigger Slope
Types of Voltage SignalsTypes of Voltage Signals
Direct Voltage (DC)Direct Voltage (DC) Alternating Current (AC)Alternating Current (AC) Frequency (Hertz)Frequency (Hertz)
SINE WAVESSINE WAVES
SINE FUNCTION SINE FUNCTION CYCLECYCLE ““0” LINE0” LINE
4 TYPES OF ELECTRICAL4 TYPES OF ELECTRICALSIGNALSSIGNALS
TYPE ONE - DC TYPE ONE - DC • Direct Current - Straight Line on ScopeDirect Current - Straight Line on Scope• Varying Voltage SignalVarying Voltage Signal– Switched VoltageSwitched Voltage– Voltage SweepVoltage Sweep
TYPE TWO - ACTYPE TWO - AC
VARYING ABOVE AND BELOW 0 VARYING ABOVE AND BELOW 0 VOLTSVOLTS
NOT SINUSOIDAL ON AUTOMOTIVENOT SINUSOIDAL ON AUTOMOTIVE IS USUALLY SAW TOOTH SIGNALIS USUALLY SAW TOOTH SIGNAL
TYPE THREE-PULSE TRAINTYPE THREE-PULSE TRAIN
VARIABLE FREQUENCY (pip,maf)VARIABLE FREQUENCY (pip,maf)• Number of cycles that happen in one secondNumber of cycles that happen in one second
VARIABLE DUTY CYCLEVARIABLE DUTY CYCLE• measurement comparing signal on-time to the measurement comparing signal on-time to the
length of one complete cycle (m/c solenoids)length of one complete cycle (m/c solenoids) VARIABLE PULSE WIDTHVARIABLE PULSE WIDTH• Actual on-time of a signal measured in Actual on-time of a signal measured in
milliseconds. (fuel injection)milliseconds. (fuel injection)
TYPE FOUR - SERIAL DATATYPE FOUR - SERIAL DATA
SERIES OF PULSES IN SPECIFIC SERIES OF PULSES IN SPECIFIC ORDERORDER
LIKE MORSE CODELIKE MORSE CODE INFO TO SCAN TOOLSINFO TO SCAN TOOLS INFO BETWEEN BCM’SINFO BETWEEN BCM’S
SIGNAL CHARACTERISTICSSIGNAL CHARACTERISTICS
CAN MEASURE THREE CAN MEASURE THREE CHARACTERISTICS OF CHARACTERISTICS OF WAVEFORMSWAVEFORMS• AMPLITUDEAMPLITUDE• FREQUENCYFREQUENCY• SEQUENCE OF EVENTSSEQUENCE OF EVENTS
DC SIGNAL FAILURESDC SIGNAL FAILURES
MUST KNOW THREE THINGSMUST KNOW THREE THINGS• What are the voltage levels for this circuit?What are the voltage levels for this circuit?• What voltage changes should take place What voltage changes should take place
while you’re testing the circuit?while you’re testing the circuit?• What does the voltage do as the failure What does the voltage do as the failure
occurs?occurs?
ON-TIME VS. OFF-TIMEON-TIME VS. OFF-TIME
ON TIME: Is the time that the circuit is ON TIME: Is the time that the circuit is energized in one cycle.energized in one cycle.• Can be either the upper or lower pulse.Can be either the upper or lower pulse.• Ground ControlledGround Controlled• Feed ControlledFeed Controlled
THE ENDTHE END
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