6. Move the channel 1 vertical cursor so that it aligns with the rising edge of the input square wave. Move the channel 2 vertical cursor so the voltage reads about 1.63 volts. The ΔT between the cursors is about 1 time constant in seconds.
ECE 1101 Laboratory Exercise 9 Capacitor Characteristics and Step Response of RC Circuit and Use of Oscilloscope as a Capacitance Meter 7. Measure the capacitance value and then calculate the % error. Error =[( Ccalculated – C measured)/Cmeasured] X 100= _____________ 8. Figure 7-2 is a typical discharge curve of a capacitor. The square wave is the input voltage to the capacitor. The resistance in series with the capacitor limits the response speed of the capacitor. Ideally you would like the capacitor to reach the same voltage as the input square in a quarter of a cycle. Figure 7- 2. Response curve of a capacitor. Figure 7-3 shows the controls of the myDAQ signal generator. It is limited in frequency and amplitude output.
ECE 1101 Laboratory Exercise 9 Capacitor Characteristics and Step Response of RC Circuit and Use of Oscilloscope as a Capacitance Meter Figure7- 3. myDAQ Signal Generator Questions 1. Describe how you measure the frequency of a waveform from the oscilloscope display if you didn’t have soft keys to measure it automatically.
ECE 1101 Laboratory Exercise 10 Inductor Characteristics and Step Response of RL Circuits ECE 1101 Laboratory Exercise 10 Inductor Characteristics and Step Repsponce of RL Circuits OBJECTIVES Gain experience in using an oscilloscope to measure the inductance of an unknown inductor. This method can also be used to measure unknown capacitance. Gain experience in using a function generator to create time varying test signals. Gain experience in properly using an oscilloscope’s controls and cursors to make measurements EQUIPMENT REQUIRED (with and without a myDAQ) One banana cable Two BNC cables One lot of clip leads and/or jumper wires DMM (digital multimeter) myDAQ or the bench top instruments Function waveform generator Unknown Capacitor Obtain capacitor (0.22 F ) and 100 K resistor from instructor or a capacitor (0.005) F and 16 K resistor . Capacitors and resistors are available in the 5 th floor student lab. Prelab Watch the following video on YouTube on how to use the myDAQ oscilloscope. . There are numerous videos on YouTube on how to measure capacitance using an oscilloscope. Watch on or more of these. BACKGROUND The oscilloscope is primarily a voltmeter forobserving time varying signals. It has a fairly low input impedance of one megohm (1M ) so it cannot be used when a load impedance of this size would distort the signal being measured. It is an excellent tool for measuring transient phenomenon such as impact forces on a load cell. Some oscilloscopes can operate in both a digital mode and analog mode. However, the myDAQ can only operate in the digital mode. They also have built-in computers for
ECE 1101 Laboratory Exercise 10
- Winter '18
- Voltage divider, Resistor, bridge circuit