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