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  1. igneous Methamorphic

  2. RESISTORS ACCORDING TO COMPOSITION

  3. O B J E C T I V E S • Identify the types of resistors. • Discuss the importance of each resistor. • Differentiate each according to usage and composition.

  4. RESISTORS One of themostcommonelectroniccomponentsused as a devicethatlimits, orresistscurrent and produces a desiredamount of voltage in thecircuitisthe resistor. It can bemadefromdifferentmaterials, butthemostcommonisthecarboncomposition. Thecurrentlimitingability, orresistance can bevariedbychangingthe ratio of carbontobindingagent.

  5. ACCORDING TO COMPOSITION • CarbonCompositionResistors • Standard Film Resistors • Chip Resistors • Network Resistors • Wire-WoundResistors • Potentiometers • Rheostats

  6. CARBON COMPOSITION CCRs are madeeitherbyhotorcoldmoldingfrom mixtures of carbon and claybinder. These has become a dominantdiscrete resistor mainlyforitslow-costreliabilty in general purposeapplications and foritsresistivetolerances of ±5% to ±20%.

  7. Itsresistivevaluerangesfrom 10 ohmstomegaohms, in power ratings from 1/8 to 4 watts . It has abilitytowithstandhighercurrent surges and ruggedness. Itisusednotonlyforcommercialbutalsoformilitary and aerospaceapplications.

  8. STANDARD FILM A circular resistor withtwopinsextendingfromoppositesidesorthebarrel-shapedresistors.

  9. CHIP RESISTOR Thistype of resistor wasintroduced in the late 80´s toaccomodatefortheevershrinkingcomputercomponentswherethere can be up to 6 layers per circuitboard.

  10. NETWORK RESISTOR Thistype of resistor comes in compact form and can contain up to 12 resistors in a compact space.

  11. WIRE- WOUND RESISTORS Thistype of resistor has a highlyresistivewireswrappedaroundaninsulatingcore. Insulatingcores are usuallymade of cementorceramicmaterialsorjustplainpaperorpressedcardboard.

  12. Sincebarewires are usedfordesiredresistance, theunitisencasedbyaninsulating material. Thistype of resistor provideslowresistancewithhighwattagesrangingfrom 5 to 100 wattsor more. They are bestchoice in applicationswhereaccurate and stableresitances are necessary.

  13. These are resistors in whichtheresistiveelementis a length of highresistancewireorribbonusuaalynichromewoundontoaninsulatingform.

  14. POTENTIOMETER These are manufactured in a widerangestartingfrom 1 wattto 5000 watts. Thesemaybe open type, perforatedtype, and gradedtype. Thestandardtoleranceis ±10% butclosertolerance can bealsosupplied.

  15. RHEOSTATS The most common way to vary the resistance in a circuit is to use a rheostat.The word "rheostat" was coined about 1845 by Sir Charles Wheatstone, from the Greek word rheos meaning stream, and stat meaning regulating device, which is a two-terminal variable resistor. For low-power applications (less than about 1 watt) a three-terminal potentiometer is often used, with one terminal unconnected or connected to the wiper.

  16. Any potentiometer may be connected as a rheostat. RHEOSTATS

  17. QUIZ NO. 2 RESISTORS