The purpose of this lab is to model and observe the behavior of an RLC circuit containing two resistors, a capacitor, and an inductor. A step voltage input of 2V will be applied to the circuit, and the effects will be observed using the oscilliscope in the Waveforms program. We will use our knowledge of second order circuits to calculate the rise time and the DC gain of the step response. Pictured below is a diagram of the circuit to be modeled in this lab:
For the circuit above, Vin = 2V (step), R1 = 47 Ohm, R2 = 1.1 Ohm, C = 1 uF, and L = 1 mH. Voltage will be measured across R2. Before building the circuit, we did lots of math in order to determine the equations for voltage and current, which were used to find the rise time of the circuit. Andrew just plugged the equation into maple and found a solution which turned out to be much more accurate.
By hand, rise time was found to be 0.48 ms (underdamped circuit)
On maple, rise time was found to be 0.33 ms
Actual circuit used
Step function input for voltage supply. f = 100 Hz
Voltage across R2.
It can be seen in the photo above that rise time looks to be ~0.3 ms, which tells us that maple does a much better job at doing math than humans. Everycircuit was used to confirm our results, which shows the exact same behavior as shown in our actual circuit.
In Class Examples
1. Calculate i(t) for t>0 using the circuit shown below:
2. Find iL(t)
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