This is my new problem to solve!
See attached picture!
The problem asks to calculate Vo and Ro for the given circuit. The zener has an internal dynamic impedance of 100 Ω. I'm considering that these 100 Ω is a resistor in series with a battery, simulating an approximation model for that zener. I'm only testing the voltage supply value of 15 V to check if the method is ok or not... Then I'll just plug in the 15 V  1 V and the 15 V + 1 V to actually check the final results!
I already tried to solve this using the Thévenin equivalent method.
Vth would be the zener voltage plus the voltage drop across the 100 Ω resistor.
I'm calling this resistor as Rz.
So, I evaluated a symbolic equation for the net closed loop, without the Load resistor. Being I, the current flowing through this branch:
Vin = I*R1 + Vz + I*Rz
I = (Vin  Vz) / (R1 + Rz)
So Vth:
Vth = Vz + I*Rz
Vth = Vz + Rz*( (Vin  Vz) / (R1 + Rz) )  V + Ω*(V/Ω) = V, checks
Vth = 5.9 V
And Rth:
Rth = R1  Rz = (1 kΩ*100 Ω) / (1 kΩ + 100 Ω) = 91 Ω
But then I tried using net closed loop equations and nodal equations.
For net closed loop equations I called the current flowing through R1 as I1 and I did:
Vin + I1*R1 + Vz + Iz*Rz = 0 V
Vin + I1*R1 + I_Load*R_Load = 0 V
I_Load*R_Load  Iz*Rz  Vz = 0V
Solving this for I1, Iz and I_Load, I'm getting Iz = 0A and that doesn't adds up. It can't be... Where am I going wrong?
Then I tried a Nodal equation for the node between the zener and R1 and I called it V1, which is the Vo I'm looking for.
I did:
I1 = I_Load + Iz
or
I1 = I_Load + I_Rz
as the current flowing through the zener is the same as the current flowing through Rz!
Then I wrote that:
I1 = (Vin  V1) / R1
I_Rz = (V1  Vz) / Rz
I_Load = V1 / R_Load
(Vin  V1) / R1 = (V1 / R_Load) + ( (V1  Vz) / Rz)
Solving this for V1 I'm getting V1 = 5.42 V
So, I'm not getting consistent values! I need some help here!
See attached picture!
The problem asks to calculate Vo and Ro for the given circuit. The zener has an internal dynamic impedance of 100 Ω. I'm considering that these 100 Ω is a resistor in series with a battery, simulating an approximation model for that zener. I'm only testing the voltage supply value of 15 V to check if the method is ok or not... Then I'll just plug in the 15 V  1 V and the 15 V + 1 V to actually check the final results!
I already tried to solve this using the Thévenin equivalent method.
Vth would be the zener voltage plus the voltage drop across the 100 Ω resistor.
I'm calling this resistor as Rz.
So, I evaluated a symbolic equation for the net closed loop, without the Load resistor. Being I, the current flowing through this branch:
Vin = I*R1 + Vz + I*Rz
I = (Vin  Vz) / (R1 + Rz)
So Vth:
Vth = Vz + I*Rz
Vth = Vz + Rz*( (Vin  Vz) / (R1 + Rz) )  V + Ω*(V/Ω) = V, checks
Vth = 5.9 V
And Rth:
Rth = R1  Rz = (1 kΩ*100 Ω) / (1 kΩ + 100 Ω) = 91 Ω
But then I tried using net closed loop equations and nodal equations.
For net closed loop equations I called the current flowing through R1 as I1 and I did:
Vin + I1*R1 + Vz + Iz*Rz = 0 V
Vin + I1*R1 + I_Load*R_Load = 0 V
I_Load*R_Load  Iz*Rz  Vz = 0V
Solving this for I1, Iz and I_Load, I'm getting Iz = 0A and that doesn't adds up. It can't be... Where am I going wrong?
Then I tried a Nodal equation for the node between the zener and R1 and I called it V1, which is the Vo I'm looking for.
I did:
I1 = I_Load + Iz
or
I1 = I_Load + I_Rz
as the current flowing through the zener is the same as the current flowing through Rz!
Then I wrote that:
I1 = (Vin  V1) / R1
I_Rz = (V1  Vz) / Rz
I_Load = V1 / R_Load
(Vin  V1) / R1 = (V1 / R_Load) + ( (V1  Vz) / Rz)
Solving this for V1 I'm getting V1 = 5.42 V
So, I'm not getting consistent values! I need some help here!
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