Calculate I1, V Drop R1, V Drop R2, I2 for Circuit w/Diode

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Homework Help Overview

The discussion revolves around analyzing a circuit with a diode, focusing on calculating the current I1, voltage drops across resistors R1 and R2, and current I2. The circuit parameters include a voltage input of 5V and resistors R1 and R2 both valued at 1k ohm, with R3 at 2k ohm. The diode is assumed to be non-ideal, with a forward voltage drop of approximately 0.7V.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the currents and voltage drops using a voltage divider approach and expresses uncertainty about the correctness of their method. Some participants question the relationship between I1 and I2, particularly regarding their waveforms in a DC context versus an AC context.

Discussion Status

The discussion is ongoing, with participants exploring the implications of the diode's behavior in the circuit. There is a focus on understanding the nature of the signals involved, particularly in relation to the assumptions made about the DC source and the diode's characteristics.

Contextual Notes

Participants note the potential confusion arising from the labeling of the DC source as "Vin, VAC," which may imply additional considerations not directly related to the current problem.

pyroknife
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I attached the circuit.
I need to find I_1, Voltage drop across R1, voltage drop across R2, and I_2. We're assuming the diode is 'not' ideal.

Vin=5V. R1=R2=1kohm
R3=2kohm


voltage across R2=Vin=5V
I2=5/1kohm=5mA

The real diode drops about 0.7 V. So using voltage divider gives voltage across R1=(R1/(R1+R3))*(5-0.7)=1.43V

Then I1=1.43/1k=1.43mA


Is this the right idea?
 

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without comment on the correctness of your specific numbers, let me ask you this:

Do you feel that I2 = 5m in the same sense that I1 = 1.43ma. That is, other than magnitude, would they have the same waveform if graphed?
 
phinds said:
without comment on the correctness of your specific numbers, let me ask you this:

Do you feel that I2 = 5m in the same sense that I1 = 1.43ma. That is, other than magnitude, would they have the same waveform if graphed?
I guess I don't see what you're asking.
This is a DC signal.

For an AC signal, the would not have the same wave form due to the diode.
 
pyroknife said:
I guess I don't see what you're asking.
This is a DC signal.

For an AC signal, the would not have the same wave form due to the diode.

Hm ... why do you suppose a DC source is labeled "Vin, VAC ?"
 
phinds said:
Hm ... why do you suppose a DC source is labeled "Vin, VAC ?"

Ignore the AC part, that's for another problem.
 

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