ELEC UNIT 12 Flashcards
(12.1) What old technology do transistors replace?
vacuum tubes
(12.1) How are the terms “solid state” and “semi-conductor” different?
solid state refers to physical description of component, semiconductor refers to the electrical conductivity of component.
(12.1) define semi-conductor
a conductor who’s conductivity is between that of an insulator and a highly conductive metal.
(12.1) What 2 components make up a transistor?
the thermistor and the varistor
(12.1) What is a thermistor
a semi-conductor with a positive or negative temperature/resistance coefficient.
(12.1) What does a thermistor do?
a semi-conductor that’s resistance decreases as the applied voltage increases.
(12.1) what materials are most common in semi-conductors?
germanium and silicon (silicon is most common)
(12.1) What is an N-type material in a semi-conductor?
a semi-conductor paired with a material with free electrons (negatively charged material)
(12.1) What is a P-type material in a semi-conductor?
a semi-conductor paired with a material with holes (a lack of electrons, making it positively charged).
(12.1) what is the difference between diodes and rectifiers?
diodes are rated at less than 1 A, and rectifiers are rated at more than 1 A.
(12.1) What do diodes and rectifiers do?
they allow current flow in one direction, which makes them useful in rectifying AC into DC.
(12.1) What is the symbol for a diode or a rectifier on a schematic diagram?
(12.1) What are the 2 types of transistors?
NPN and PNP.
(12.1) What are transistors used for?
they are used as a switch or to amplify a signal (like radio, but for closing another switch or driving a small motor).
(12.1) What do the 3 parts of a transistor do?
base - activates transistor
collector - positive end
emitter - negative end
(12.1) what are triacs?
transistors but with two diodes. They are used as switches and relays in AC circuits.
(12.1) what is the symbol for triacs in a schematic diagram?
(12.1) What is the symbol for LEDs in a schematic diagram?
(12.4) What does a one-function electronic control do?
solid-state devices that control one thing, like start assist a motor, prevent short cycling, etc.
(12.5) What do anti-short-cycling-timers so?
they prevent electrical loads from starting and stopping in rapid secession (from 30 sec to 5 min). as the device heats, its resistance decreases, allowing current to pass through.
(12.8) What controls the entire operation of a heat pump?
the heat pump electronic module
(12.9) What are the electronic control boards on gas furnaces usually called?
the ignition module
(12.9) What is pilot safety mode on the ignition module?
supervises the operation of the ignition of the fuel.
(12.9) When does lockout happen on a gas furnace?
when the fuel fails to ignite.
