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Electronics
Electronics Catlog
DIC - TOC

Electronics References


Ohm's and Joule's Laws


Ohm's Law

    NOTE: the symbol "V" is sometimes used to represent voltage instead of "E". In some cases, an author or circuit designer may choose to exclusively use "V" for voltage, never using the symbol "E." Other times the two symbols are used interchangeably, or "E" is used to represent voltage from a power source while "V" is used to represent voltage across a load (voltage "drop").


Kirchhoff's Laws


    "The algebraic sum of all voltages in a loop must equal zero."

    Kirchhoff's Voltage Law (KVL)

    "The algebraic sum of all currents entering and exiting a node must equal zero."

    Kirchhoff's Current Law (KCL)

Series circuit rules


    * Components in a series circuit share the same current. Itotal = I1 = I2 = . . . In

    * Total resistance in a series circuit is equal to the sum of the individual resistances, making it greater than any of the individual resistances. Rtotal = R1 + R2 + . . . Rn

    * Total voltage in a series circuit is equal to the sum of the individual voltage drops. Etotal = E1 + E2 + . . . En

Parallel circuit rules


    * Components in a parallel circuit share the same voltage. Etotal = E1 = E2 = . . . En

    * Total resistance in a parallel circuit is less than any of the individual resistances. Rtotal = 1 / (1/R1 + 1/R2 + . . . 1/Rn)

    * Total current in a parallel circuit is equal to the sum of the individual branch currents. Itotal = I1 + I2 + . . . In


Series and parallel component equivalent values


Series and parallel resistances


Series Parallel Resistances

Series and parallel inductances


Series Parallel Inductances

Series and Parallel Capacitances


Series Parallel Capacitances

Capacitor sizing equation


Capacitor Sizing

Inductor sizing equation


Inductor Sizing

Time constant equations


Value of time constant in series RC and RL circuits


    Time constant in seconds = RC

    Time constant in seconds = L/R

Calculating voltage or current at specified time


Time Constant Voltage

Calculating time at specified voltage or current


Time Constant Current

AC circuit equations


Inductive reactance


Inductive Reactance

Capacitive reactance


Capacitive Reactance

Impedance in relation to R and X


    ZL = R + jXL

    ZC = R - jXC

Ohm's Law for AC


Ohm's Law AC

Series and Parallel Impedances


Series Parallel Impedances

    NOTE: All impedances must be calculated in complex number form for these equations to work.

Resonance


Resonance

    NOTE: This equation applies to a non-resistive LC circuit. In circuits containing resistance as well as inductance and capacitance, this equation applies only to series configurations and to parallel configurations where R is very small.

AC power


AC Power

AC Power Factor

Decibels


Decibels


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