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Resistors. Resistors - Job. Oppose the flow of current Can be used as a fuse in circuitry Measured in Ohms. Resistors - Types. Fixed Variable. Resistors - Fixed - Makeup. Molded composition or carbon resistor
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Resistors - Job • Oppose the flow of current • Can be used as a fuse in circuitry • Measured in Ohms
Resistors - Types • Fixed • Variable
Resistors - Fixed - Makeup • Molded composition or carbon resistor • carbon material & binder that holds the carbon together. (type of resistors in kits) • Metal film • Wire wound • Used when large amounts of heat must be dissipated
Resistors - Fixed - Sizes • Different sizes of carbon resistors tell the amount of heatthat a given resistor can transfer or dissipate to the outside air. • 1/8, ¼, ½, 1 and 2 watts
Resistors – Fixed – Color Code Black 0 Bad Brown 1 Boys Red 2 Run Orange 3 Our Yellow 4 Young Green 5 Girls Blue 6 But Violet 7 Violet Gray 8 Goes White 9 Willingly
Resistors – Fixed – Color Code Tolerance Value: Gold 5%Silver 10%No band 20%
Resistors – Reading Color Bands • Each color represents a number. • Position the resistor with the tolerance bands (gold/silver) at your left.
Resistors – Reading Color Bands 1 2 3 4 Band 1 Yellow 4Band 2 Violet 7 Band 3 Black 0 Band 4 Gold 5%
Resistors – Reading Color Bands Band 1: Write down the number 4 Band 2: Write down the number 7 Band 3: Write down the number of zero’s Black = 0 so write down 0 zero’s Band 4: Tolerances of the resistor 5% Resistor Value: 47 Ohms 5% tolerance
Resistors – Reading Color Bands Band 1 Red 2 2 Band 2 Green 5 5 Band 3 Blue 6 000000 Band 4 Gold 5% 5% 25,000,000 Ohms or 25 Megohms
Resistors – Reading Color Bands Band 4: tolerance of resistor Minimal: 23,750,000 Ohms Maximum 26.25 Megohms
Resistors – Reading Color Bands 25 megohms x .05 = 1,250,000Minimal 25 megohms - 1,250,000 = 23750000 ohms or 23.75 megohmsMaximum 25 megohms + 1,250,000 = 26250000 ohms or 26.25 megohms
Resistors – Reading Color Bands Different ways resistance can be written: 25,000,000 ohms or 25 megohms25,000 ohms or 25 K ohms2,500,000 ohms or 2.5 megohms2,500 ohms or 2.5 K ohms250,000 ohms or 250 K ohms 250 ohms or 250 ohms
Resistors – Reading Color Bands Band 5: Percentage of failure per thousand hours of use Brown - 1.0 % Orange - 0.01% Red - 0.1 % Yellow - 0.001% (This band is rarely seen on resistors.)
Resistors – Reading Color Bands What are the colors for: 25K Ohms Band 1: Band 2: Band 3: 2.5K Ohms Band 1: Band 2: Band 3: Red Green Orange Red Green Red
Resistors - Variable • Potentiometer: know as a “pot” • Measured in Ohms • 10K ohm (example) • Value from 0 ohms – 10K ohms • AC = the measurement of the entire potentiometer (10K ohm “pot”) • AB + BC = AC A B C
Resistors – Variable AB + BC = AC entire potentiometer AC = ________ ohms AB = 1.2K ohms BC = _________ ohms 2K Ohm knob