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BASIC ELECTRICITY
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VOLTAGE
AMPERAGE
OHMS
Page 242 Autobody Text
SERIES CIRCUIT RULES
The current through each resistance is
the same.
 The sum of individual voltage drops is
equal to the source voltage
 The total circuit resistance is equal to the
sum of the individual resistance's
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Chap 1 Handout - Page 9
PARALLEL CIRCUIT RULES
The sum of the branch circuit currents is
equal to the total circuit current
 The voltage drop across each branch
circuit is the same
 The current in each branch circuit is
different if the resistance values are
different.
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Chap 1 Handout - Page 10
PARALLEL CIRCUIT RULES
CONT’D
The total circuit resistance (equivalent
resistance) is less than the value of the
lowest resistance.
 The equivalent resistance for two
resistance's in parallel is equal to the
product divided by the sum
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Chap 1 Handout - Page 10
Ohm’s Law
V = AxR
V = IxR
V = IxO
All the same
V
AxR
Chap 1 Handout - Page 8
COMMON CIRCUIT
FAILURES
-
OPEN CIRCUIT
GROUNDED CIRCUIT
SHORT CIRCUIT
POOR CONNECTIONS
Autobody Text - Page 242
DIAGNOSTIC EQUIPMENT
DIGITAL VOLT-OHMMETER
-
10 MEG OHM IMPEDANCE
DIGITAL READOUT VERY PRECISE
MULTI-METER (MULTI-USES)
DIODE TESTER
AUDIBLE CONTINUITY TESTER
OVERRANGE INDICATOR
Autobody Text - Page 243
DVOM VOLTAGE TESTS
- Power Switch
- Polarity
- Start with highest range and turn down
range until most accurate reading
- Over-range indicator
- Low battery
- Hook across (parallel) device or circuit
being tested
Autobody Text - Page 244
DVOM AMPERAGE TESTS
- Fuse Protection
- Hook in series with circuit
- Function selector adjust to most accurate
range
- Maximum amperage of meter
DVOM OHMMETER TESTS
- Isolate component to be tested
- fuse protected
- Function selector to most accurate range
Autobody Text - Page 244
TEST CONNECTIONS
Reading the DVOM
Handout
TEST LIGHTS
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NON POWERED LIGHT
- TELLS PRESENCE OF VOLTAGE
- EASY AND QUICK TO USE
- LOW INTERNAL IMPEDANCE
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SELF POWERED LIGHT
(CONTINUITY TESTER)
- WORKS LIKE OHMMETER
- LOW COST
Autobody Text - Page 245
LOGIC PROBE
TELLS PRESENCE OF VOLTAGE
 TELLS PRESENCE OF GROUND
(LOW VOLTAGE)
 WILL NOT HURT COMPUTER
CIRCUITS
 LIGHT AND AUDIBLE TYPE
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JUMPER WIRES
USED FOR TEST PURPOSES
 ABOUT 6”, 12” 3 FT, AND 15 FT.
 LARGE ENOUGH GAUGE
 DIFFERENT TERMINAL ENDS
 ALLIGATOR CLIPS
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