Saturday, March 31, 2012

#6 Thevenin Equivalents



In this lab we attempted to verify Thevenin's theorem.  The idea is that in a system of multiple power sources and loads we want to be able to easily calculate the affect of replacing one element so we reduce it into it's Thevenin equivalent (a source in series with a resistor).   We took a complex circuit and solved for it's Thevenin equivalent values(Vth =8.643V, Rth = 66ohms) and also for the value of the resistor necessary to produce an 8V drop across the load(R load min = 820 ohm).  Then we set up two circuits to verify - the first was the actual Thevenin Eq circuit and the second was the original circuit.  Our results were very accurate for the Thevenin Eq circuit but not for the original circuit.  This may have been due to a faulty breadboard and the additional wire resistance required for the full circuit.  





Component   Nominal Value           Measured Value Power or Current Rating
RTH                   66 Ω                         66.6 Ω                  0.3 W
RL2,min           825 Ω                         822 Ω                  0.3 W
VTH                   8.64 V                         8.64 V                


Config                 Theoretical Value Measured Value Percent Error
RL2 = RL2,min VLoad2 =8 V         7.98 V                  0.25%
RL2 = ∞Ω          VLoad2 =8.64 V 8.63V                  0.12%






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