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Thévenin's theorem
Thevenin’s theorem is a popular theorem, used often for analysis of electronic circuits. This theorem states that a linear circuit containing one or more sources and other linear elements can be represented by a voltage source and a resistance. Using this theorem, a model of the circuit can be developed based on its output characteristic.It was discovered in 1883 by French telegraph engineer Léon Charles Thévenin.
Introduction:
Through the use of thevenin theorem , we have the ability to reduce the complex circuit down to a simple series circuit .
The four steps involved are:
1- First Remove the load.
2- Then determine the voltage seen by the load (Vth).
3- Then replace the voltage source with a short.
4- At the end determine the resistance seen by the load (Rth).
1- Remove the load:
2- Determine the voltage seen by the load (Vth):
Since R2 is not connected at one end as it does not carry any current. Hence it cannot have a voltage drop, the voltage is present only across R3
Vth=VR3
Vth=(R3/R3+R1)*Vs
2- Determine the voltage seen by the load (Vth):
3- Replace the voltage source with a short:
4- Determine the resistance seen by the load (Rth):
Find the total resistance from the open terminal side which is called thevinin equivalent resistance (Rth) by removing actual voltage source from the circuit.
Rth=R2+(R1*R3/R1+R3)
Thevenin equivalent circuit:
Conclusion:
• Certain circuits can be simplified by using Thevenin’s Theorem.
• Equivalent Resistance is essential for the calculation of TEC.
• Ohm’s law is useful in this theorem.• A linear network can be transferred into a
voltage source.