Purpose:Demonstrate damped oscillations in an RLC circuit.
Description:Using the circuit above with a 500-Hertz square wave, damped oscillations are shown on the dual trace scope. The upper trace is the applied square wave and the lower trace shows the damped oscillations produced each time the square wave changes. The circuit can be adjusted to obtain either underdamped, overdamped, or critically damped oscillations by changing the capacitance or the resistance.
In the photograph above the horizontal scale is 250 microseconds per centimeter, the frequency of the square wave is 500 Hertz (period of 2 milliseconds), and the frequency of the damped oscillations is about 8000 Hertz (period of 125 microseconds). The capacitor is set to its maximum value and the resistor is set to about 20% of its maximum (20 kilohms).