Resistors – they are everywhere because they serve two functions:
- They limit current flowing into a node in a circuit and thus out of the node as well so they limit current into other components that can get all bent out of shape when the current is higher than the component following the resistor is rated to handle according to its “Datasheet” (Get used to googling a sequence of letter followed by some numbers followed by “datasheet” and clicking the PDF in the top three search results from google. These “Datasheets” will be necessary to pick out components or solve for component values when creating circuits…I will explain later)
- They can create voltage levels between the Supply Voltage and Ground using a simple formula and a circuit building block called a voltage divider.
Every unique component in a circuit will need a specific current and voltage at which it will function at its optimum performance and therefore you will use resistors to set the optimum current in a circuit building block and the optimum voltage in a circuit building block.
What else do resistors do that you will need to know?
- Resistor-Capacitor Networks add a time delay to circuitry allowing for all the digital processes of a computer because things need to be done in a specific order and sequence and the “RC-Network” serves the purpose of creating a signal within the “time-domain”
- Resistors are frequently drawn ni schematics as a representation of this thing called a “Load” which I’ll just define for you right now: it’s the the “end-game” power consuming, work-performing, purposeful part of the circuit. That is to say, the circuit you are designing is usually created to provide power to a “Load”. Imagine a guitar amplifier: the speaker that makes the sound is the load; a simple LED circuit: the LED is the Load; a DC Motor used to spin something: the motor is the Load; A lamp: the light-bulb, or more precisely, the tungsten filament is the load. The Resistor is used in schematics because Resistance=(Voltage/Current) and since -as previously stated- Circuit components have optimum Voltages and Currents, they can be neatly defined as the ratio of one to the other. That ratio is the Load’s Resistance.