Part A: Strain Gauges:
Strain gauges are used to measure the strain or stress levels on the materials. Alternatively, pressure on the strain gauge causes a generated voltage and it can be used as an energy harvester. You will be given either the flapping or tapping type gauge. When you test the circle buzzer type gauge, you will lay it flat on the table and tap on it. If it is the long rectangle one, you will flap the piece to generate voltage.
1. Connect the oscilloscope probes to the strain gauge. Record the peak voltage values (positive and negative) by flipping/tapping the gauge with low and high pressure. Make sure to set the oscilloscope horizontal and vertical scales appropriately so you can read the values. DO NOT USE the measure tool of the oscilloscope. Adjust your oscilloscope so you can read the values from the screen. Fill out Table 1 and provide photos of the oscilloscope.
Table1.1: show measurements of minimum and maximum value. 
Table1.2: shows measurements of minimum and maximum value. 
Graph1.1: show the plot of Low flipping strength 
Graph1.2: show graph of high tapping strength 
2. Press the “Single” button below the Autoscale button on the oscilloscope. This mode will allow you to capture a single change at the output. Adjust your time and amplitude scales so you have the best resolution for your signal when you flip/tap your strain gauge. Provide a photo of the oscilloscope graph.
Graph2.1: show the plot of single change at the tapping output. 

Part B: HalfWave Rectifiers
1. Construct the following halfwave rectifier. Measure the input and the output using the oscilloscope and provide a snapshot of the outputs.
Graph3.1: show the input of the circuit. 

Period
for output is 1 ms
2. Calculate the effective voltage of the input and output and compare the values with the measured ones by completing the following table.
Table2.1: show the calculated and measured values for the effective input and output. 
3. Explain how you calculated the rms values. Do calculated and measured values match?
picture3.1: show the formulas for the effective value of the input and the output. 
and Voutpu=Vpeak/pi for the output voltage and we got the same result which means that our measurements
weren't accurate.
4. Construct the following circuit and record the output voltage using both DMM and the oscilloscope.
In our circuit we used an amplitude of 5 V and output of the mean voltage and the output of the pkpk voltage, when we measured the output voltage of the pkpk by the DMM we couldn't read any value.
5. Replace the 1 µF capacitor with 100 µF and repeat the previous step. What has changed?
In our circuit we used an amplitude of 5 V and output of the mean voltage and the output of the pkpk voltage, when we measured the output voltage of the pkpk by the DMM we couldn't read any value. when we used a 100 micro farad capacitor, the values changed and we can see that the output voltage of the mean increased and the output voltage peakpeak decreased.
Part C: Energy Harvesters
1. Construct the halfwave rectifier circuit without the resistor but with the 1 µF capacitor. Instead of the function generator, use the strain gauge. Discharge the capacitor every time you start a new measurement. Flip/tap your strain gauge and observe the output voltage. Fill out the table below:
2. Briefly explain your results.
The more the strain gauge was flipped, if it was a higher frequency of flips or a longer period of time, the more the capacitor was charged giving a higher output voltage.
3. If we do not use the diode in the circuit (i.e. using only strain gauge to charge the capacitor), what would you observe at the output? Why?
If we didn't use the diode in the circuit we would see more of an AC output from the capacitor where it varies up and down. Because the diode is not in place to turn the voltage into a DC source.
4. Write a MATLAB code to plot the date in table of Part C1.
clear all;
close all;
x = [ 10 20 30];
y1 = [ 2.12 2.15 2.17];
y2 = [ 2.21 3.02 3.11];
plot (x, y1, 'o', x, y2, 's')
grid on
xlabel('Time (s)')
ylabel('Vout (v)')
legend('1 Tap per second','4 Taps per second')
Table 4.1: show the output values by using oscilloscope and DMM. 
5. Replace the 1 µF capacitor with 100 µF and repeat the previous step. What has changed?

Part C: Energy Harvesters
1. Construct the halfwave rectifier circuit without the resistor but with the 1 µF capacitor. Instead of the function generator, use the strain gauge. Discharge the capacitor every time you start a new measurement. Flip/tap your strain gauge and observe the output voltage. Fill out the table below:
Table C1.1: shows the output voltage of the flipping strain gauge. 
The more the strain gauge was flipped, if it was a higher frequency of flips or a longer period of time, the more the capacitor was charged giving a higher output voltage.
3. If we do not use the diode in the circuit (i.e. using only strain gauge to charge the capacitor), what would you observe at the output? Why?
If we didn't use the diode in the circuit we would see more of an AC output from the capacitor where it varies up and down. Because the diode is not in place to turn the voltage into a DC source.
4. Write a MATLAB code to plot the date in table of Part C1.
clear all;
close all;
x = [ 10 20 30];
y1 = [ 2.12 2.15 2.17];
y2 = [ 2.21 3.02 3.11];
plot (x, y1, 'o', x, y2, 's')
grid on
xlabel('Time (s)')
ylabel('Vout (v)')
legend('1 Tap per second','4 Taps per second')
Graph C4.1 Shows the MatLab graph using the code above 
Nice job this week. for number 1 our flipper had higher output than yours and your button had higher than ours. our oscilloscope data looked similar though, most of our graphs were practically identical. however, for part c the table, our voltage for 4flips/second decreased rather than increased like yours. we aren't sure why this is.
ReplyDeleteFor part c, we only did the flip frequency, I think that the tap frequency will decrease and the the flip frequency increase.
DeleteGood job this week. Most of the data looks really similar to ours, including the graphs. Our Matlab graph does look a little bit different than yours. Im guessing its because we didn't tap the same way therefore not getting the same data.
ReplyDeleteI agree with your guess, i think it depends on how strong we tap. Thanks for your comment.
Delete