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Electronic Formulas

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[edit] Power

  • W = Watt
  • J = Joule
  • S = Second


W = \frac{J}{S}

[edit] Transformer inductance and coupling

M = k \sqrt{(L_1)(L_2}

Where:

  • M = Mutual inductance in Henrys
  • k = coefficient of coupling
  • L_1 Inductance of first winding
  • L_2 Inductance of second winding

[edit] Turns ratio

For Iron Core \frac{N_s}{N_p} = \frac{E_s}{E_p} = \frac{I_p}{I_s}

Where:

  • p subscript refers to Primary winding
  • s subscript refers to secondary winding
  • N = number of turns

[edit] Ohms law in magnetics

Where:

  • F = repulsive force
  • r = distance between poles
  • μ permeability ( μ of air = 1)
  • H = Magnetizing Force in Oersted
  • mmf = Magnetic Motive Force - in Gilberts
  • Orested = Gilberts/CM
  • β = Flux density in Gauss
  • φ = Total flux density in Maxwells
  • r = Reluctance

mmf = φR

F = \frac{m_1m_2}{\mu r^2}


H = \frac{F}{m_2} = \frac{m_1}{\mu r^2}


[edit] Impedance

Where

  • XL refers to inductive reactance
  • XC refers to capacitive reactance

X_C = \frac{1}{2\pi Cf}

\,\! X_L = 2\pi Lf

[edit] Impedance through a transformer

\frac{Z_p}{Z_s} = \left(\frac{N_p}{N_s}\right)^2

[edit] Series RCL

Z = \sqrt{R^2 + \left(X_L -X_C\right)^2}


[edit] Parallel RCL

Z = \frac{1}{\sqrt{\frac{1}{R^2} +\left( \frac{1}{X_L} - \frac{1}{X_C}\right)^2}}

[edit] Parallel LC Resonance

f_r = \frac{1}{2\pi\sqrt{LC}}

[edit] Q or Quality factor

Q = \frac{X}{R}

[edit] Time constance

Τ = time in seconds to 2/3 rise

Τ = RC

\Tau = \frac{L}{R}

[edit] Power factor

P_f = \frac{True\;power}{apparent\;power} = \frac{I^2R}{VA} = \frac{R}{Z} = \cos\theta

[edit] Standing Wave Ratio (SWR)

SWR = \frac{E_{max}}{E_{min}} = \frac{I_{max}}{I_{min}} = \frac{Z_1}{Z_2}

[edit] Modulation

%Modulation = \frac{E_{max} - E_{min}}{2E_{carrier}}\left( 100% \right)

Deviation\ Ratio = \frac{Max\ Deviation}{Highest\ Modulating\ Frequency}


[edit] ESR formulas

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