I searched a lot and saw many videos and every time it get's more complicated..what is the difference between time domain and Freq. domain and phasor domain in circuit analysis ? when should we use each one ? and how we transform a Fn. from one domain to another ?
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\$\begingroup\$ I hear this terms a lot in lecture and profs don't take time to explain them \$\endgroup\$– user86473Sep 29, 2015 at 16:32
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\$\begingroup\$ There are TONS of material about this stuff around the internet. \$\endgroup\$– Eugene Sh.Sep 29, 2015 at 17:13
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The time domain is pretty easy. \$ I_0 sin(wt) \$ The signal varies with time \$t\$ with the frequency \$w\$. The problem with this notation is that i's difficult to deal with delays and comparing the original signal to the delayed one \$ I_0 sin(wt - T) \$ for example. The solution is to transform the signal to the phasor domain. This gives the ability to compare signal timing in degrees instead of time. For example two sine waves that are 360 degrees out of phase line up again. The downside of straight phasors is that every signal in the analysis must be at the same frequency and there is no compensation for components that are frequency sensitive (inductors and capacitors).
The frequency domain transforms all frequency sensitive components to compensate them for frequency. The frequency domain still uses phasor notation. If frequency domain you can also deal with multiple frequency signal but to do that you must use super position.
To move from time to frequency just use a Laplace transform. To move from time to phasor figure out how much delay or advance the signal has \$ degress/360 = T/period \$
