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

In summary, this conversation is discussing the calculation of various electrical values such as I_1 and voltage drop across R1 and R2, assuming a non-ideal diode and given specific values for Vin, R1, R2, and R3. The voltage across R2 is equal to Vin and I2 can be calculated using Ohm's Law. The voltage across R1 is calculated using a voltage divider, taking into account the voltage drop of the diode, and I1 can then be determined using Ohm's Law. The conversation also briefly touches on the difference between DC and AC signals.
  • #1
pyroknife
613
3
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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  • #2
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?
 
  • #3
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.
 
  • #4
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 ?"
 
  • #5
phinds said:
Hm ... why do you suppose a DC source is labeled "Vin, VAC ?"

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

1. What is the purpose of calculating I1, V Drop R1, V Drop R2, and I2 for a circuit with a diode?

The purpose of these calculations is to understand the behavior of the circuit and the flow of current and voltage through the diode and resistors. This information can help in designing and troubleshooting electronic circuits.

2. How do I calculate I1 in a circuit with a diode?

To calculate I1, you need to use the Kirchhoff's Current Law (KCL) which states that the sum of currents entering a node must equal the sum of currents leaving that node. So, you can use this law to set up and solve equations to find the value of I1.

3. How do I calculate V Drop R1 and V Drop R2 in a circuit with a diode?

To calculate V Drop R1 and V Drop R2, you need to use Ohm's Law which states that the voltage drop across a resistor is equal to the current through the resistor multiplied by its resistance. So, you can use this law to calculate the voltage drops across R1 and R2.

4. How do I calculate I2 in a circuit with a diode?

To calculate I2, you need to use the diode equation which states that the current through a diode is equal to the saturation current multiplied by the exponential of the ratio of the voltage applied across the diode to the thermal voltage. You can use this equation to calculate the value of I2.

5. Can I use these calculations for any circuit with a diode?

While the principles and equations used to calculate I1, V Drop R1, V Drop R2, and I2 are applicable for most circuits with a diode, the values may vary depending on the specific components and circuit design. It is always important to double check your calculations and take into account any unique features of the circuit.

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