RESISTORS

1
CHAPTER 5

• RESISTORS

2
(No Transcript)
3
(No Transcript)
4
USES OF RESISTORS
1. LIMIT CURRENT FLOW 2. ACT AS A VOLTAGE DIVIDER
5
I E/R 15V / 30 OHMS .5 AMPS I E/R 15V /
.0001 OHMS 150000 AMPS
6
IE/R17.5/300 .05AMPS A TO B (EI x R.05Ax30
OHMS 1.5V) B TO C (EI x R.05A x 120 OHMS
6V) C TO D (EI x R .05 x 200 OHMS 10 V)
7
FIXED RESISTORS

• HAVE ONLY 1 OHMIC VALUE WHICH CANNOT BE CHANGED
• TYPES INCLUDE COMPOSITION CARBON, METAL FILM,
  CARBON FILM, METAL GLAZE, AND WIRE WOUND

8
RESISTOR POWER RATINGS
IF POWER RATING IS EXCEEDED LET THE SMOKE OUT IT
9
MOST COMMON TYPE MADE OF CARBON GRAPHITE AND A
RESIN BONDING MATERIAL INEXPENSIVE HAVE RANGE OF
1 TO 22 MEGOHMS POWER RATINGS OF
1/8,1/4,1/2,1,AND 2 WATT TOLERANCE RANGES OF 20,
10, 5
10
WIRE WOUND RESISTORS
MADE BY WINDING A PIECE OF RESISTIVE WIRE
AROUND A CERAMIC CORE USED WHEN A HIGH
POWER RATING IS NEEDED ALLOWS AIR TO COOL BY
FLOWING THROUGH IT SHOULD BE MOUNTED VERTICALLY
CHIMNEY EFFECT
11
STEPPED WIRE WOUND USED ON BLOWER MOTORS TO
CONTROL SPEED
12
1st Band 1st Number 2nd Band 2nd Number 3rd
Band Multiplier 4th Band Tolerance If it has
5th Band 1 Tolerance If a resistor is
replaced, use same tolerance equal value
13
(No Transcript)
14
1500 ohms with 10 tolerance
15
(No Transcript)
16
VARIABLE RESISTORS

• A RESISTOR WHOSE VALUE CAN CHANGED OR VARIED OVER
  A RANGE
• AVAILABLE IN DIFFERENT CASE STYLES AND POWER
  RATINGS
• TYPES INCLUDE RHEOSTATS, POTENTIOMETERS,
  THERMISTORS, PHOTO-RESISTORS

17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
RHEOSTATS

• TWO WIRE VARIABLE RESISTOR
• HAS MOVEABLE LEVER THAT VARIES RESISTANCE
• EXAMPLES DASH LIGHTS DIMMER, FUEL SENDING
  UNITS, WIPER DELAY SWITCHES

26
POTENTIOMETERS

• THREE WIRE VARIABLE RESISTOR
• USED AS A POSITION INDICATOR (INPUT TO A LOGIC
  DEVICE)
• EXAMPLES THROTTLE POSITION SENSOR (TPS), EGR
  POSITION SENSOR, HVAC DOOR POSITION SENSOR

27
THERMISTORS

• TWO WIRE SENSORS
• RESISTANCE VARIES WITH TEMP
• CAN BE PTC OR NTC
• USED AS INPUT TO A LOGIC DEVICE
• EXAMPLES COOLANT TEMP SENSOR, INTAKE AIR TEMP
  SENSOR, BATTERY TEMP SENSOR, IN CAR TEMP SENSOR

28
PHOTO RESISTORS

• TWO WIRE VARIABLE RESISTORS
• RESISTANCE CHANGES WITH DIFFERENT LEVELS OF LIGHT
  INPUT
• EXAMPLES AUTOMATIC HEADLIGHTS, SUNLOAD SENSORS
  ON HVAC SYSTEMS, ASSEMLY LINE SWITCH INPUT

29
REVIEW

• 1. NAME TWO FUNCTION OF RESISTORS?
• 2. WHAT IS FIXED RESISTOR?
• 3. NAME THREE TYPES OF FIXED RESISTORS?
• 4. WHAT EFFECTS POWER RATING?

• 5. NAME AN ADVANTAGE OF WIRE WOUND RESISTOR.
• 6. WHAT ARE THE COLORS FOR?
• 7. WHAT IS A VARIABLE RESISTOR?
• 8. NAME THREE TYPES OF VAR. RESISTORS.

30
THATS ALL FOLKS!!!