Where is the Error in this AC/DC Circuit Analysis?

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SUMMARY

The discussion focuses on identifying errors in the analysis of an AC/DC circuit involving a DC voltage source (V1) and an oscillating source with frequency omega. The equations governing the circuit include current calculations through two resistors (R1 and R2) and the relationship between voltage (V) and current (I) across a capacitor. The user highlights inconsistencies in the current across R1 and seeks clarification on the setup, particularly regarding the sign and direction of I1. The conclusion emphasizes the need for careful attention to the signs in the equations to ensure a coherent solution.

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Electrical engineering students, circuit designers, and professionals involved in AC/DC circuit analysis will benefit from this discussion, particularly those troubleshooting circuit inconsistencies.

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See picture, sorry that it's huge. V1 is a DC voltage and there is also an oscillating source of frequency omega. Let V be the voltage between the two resistors, I be the current exiting the cap, and I1 and I2 be the currents through the 2 resistors. Then we have: ## I_1 = (V - V_1) / R_1## , ## I_2 = V / R_2##, ##I_1 + I = I_2 ##, and ## I = - C \frac{d}{dt} (V - V_0 \cos (\omega t)) ##. Combining gives ## -C \frac{d}{dt} (V - V_0 \cos (\omega t )) = V / R_2 - (V - V_1)/ R_1 = V( 1/R_2 - 1/R_1) + V_1 / R_1##. The constant term can be eliminated with a substitution, and then the sign on the right hand side can be chosen to give a homogenous solution of the form ##e^{ax} ## with ##a > 0##, by choosing ##R_1## accordingly. This obviously makes no sense. Can someone see where I am setting this up wrong?
 
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The sign or direction of I1 looks inconsistent.
 
Sorry for not updating. The current across R1 is inconsistent. Thanks.
 
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