I want to find the Thévenin resistance from the terminals a-b. I've been trying out various methods that look correct to me but none of them seem to be the right answer: 4/9 kΩ.
First, according to
KCL at node
A I've considered that the current going through the right loop is
5I1 since the current going through the left loop is just
I1 and the dependent source provides
With this in mind I tried:
- Transforming the dependent current source into a dependent voltage source, which gave me two resistors in series
R3 + R1, which I added and then I transformed it back to a current dependent source. Now the Thévenin-Norton resistance should be the parallel resistors
R3+R1 // R2 = 2/3which is wrong (not 4/9);
- Then I tried calculating the Thévenin voltage at
a-band the Norton current by short-circuiting
a-band then apply
Rth = Vth/In.
In = 5I1and
Vth=5I1x1and of course is not right either.
How can I calculate
Rth in this setup? Also, I don't understand why the methods I've applied are wrong.