# Two source circuit thevenin and norton

1. Sep 26, 2007

### Fys

Can someone help me detemine The thevenin Voltage, the thevenin resistance and the Norton current of this circuit
I can't solve it cause it has two current sources

Thank you

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• ###### Thevenin.bmp
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2. Sep 26, 2007

### edmondng

what is thevenin voltage and norton current. explain to me the rules

3. Sep 26, 2007

### Defennder

Well, it does look like I would have to assume that both current sources are independent. With this assumption, I zero all the sources and I'll be left with the Thevenin resistance of 7924 ohms. The short-circuit current may be calculated by simply connecting the terminals on the far right with a zero-resistance wire and calculating the current through it. After doing the above, note that no current flows through the 15k Ohm resistor, so we may simply remove it, and that all the current from the 2mA source will flow through the short-circuit wire. Now all that remains is to find the current from the 3mA source flowing through the shorted terminals.

To do this, I use node-voltage analysis and assign node V1 to the top left hand corner of the circuit. After constructing the equations and solving for V1, which I got 12.14V. Using this value, I found that the current through the 6.8k Ohm reistor is 1/560 A. The short-circuit current may then be calculated by adding 2mA to 1/560 A, which gives 0.00379 A. The Thevenin voltage may be then be easily calculated. The Norton current is simply the shortcircuit current.

I'm not sure if I'm entirely correct. So could anyone double-check the above answers?

Thevenin and Norton equivalent circuits are electrically equivalent circuits whereby complex circuits may be redrawn so that they consist of only a voltage source and a resistance in series (thevenin) or a current source and resistance in parallel. By electrically equivalent I mean that replacing part of a circuit with its Thevenin or Norton equivalent will not change anything (eg. current, voltage measurements) in the circuit external to the Thevenin or Norton part of the circuit.