I'm currently trying to gain an understanding of Thévenin and Norton equivalent circuits and I've run into a circuit I simply don't understand. I've been researching online, but I've just run into contradictory information that often isn't helpful to begin with.

Here's the circuit: Here's the circuit:

I could simplify this circuit, but that ideal current source is my big roadblock. I'm currently trying to find the voltage between A and B.

I don't even know where to start. If someone could show me the right direction, that would be great! Thanks

  • 3
    \$\begingroup\$ If you don't see any clever ways to simplify the circuit, you can just resort to superposition. \$\endgroup\$
    – The Photon
    Commented Oct 4, 2016 at 4:23
  • 4
    \$\begingroup\$ The voltage betwen A and B is simply 3A x 48 Ohm \$\endgroup\$ Commented Oct 4, 2016 at 7:35
  • \$\begingroup\$ If you replace the current source with open circuit (because its internal impedance is infinity, theoretically) then you'll see that the voltage across 48Ohm resistor is not affected by 5V voltage source. Thus, as @ClaudioAviChami stated, voltage across 48Ohm resistor is simply 3A x 48Ohm. \$\endgroup\$ Commented Oct 4, 2016 at 19:46

2 Answers 2


The leftmost 100 ohm resistor from your schematic can be excluded form analysis - voltage across it is constant at 5V. Let assume that current in the 160 ohm resistor is I2 and current in 50+50 ohm resistor is I1. One than can write following equations : I1 + I2 = 3A, I2*160 - 5V - I1*100 = 0. Hope this helps.


simulate this circuit – Schematic created using CircuitLab


There is no mystery here. The Vab is shown below,

enter image description here

The software allows you to double check the result, however, to determine the actual voltage in Thévenin configuration, you turn on the independent sources and determine the voltage at AB. (Hint: see Ohm's law).


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