## Week Eleven

### Not Shocking People While Generating eNeRgY

#### Part 1: Strain Gauges:

**Problem 1:**

*Figure 1: Minimum and Maximum Voltages measured (Volts)*

*Figure 2: Low intensity flipping observation*

*Figure 3: High Intensity Flipping Observation*

*Figure 4: Low intensity tapping observation*

*Figure 5: High Intensity Tapping Observatinon*

**Problem 2:**

*Figure 6: Single Sequence tapping output*

*Figure 7: Single Sequence Flipping output*

**Part B:**

**Problem 1:**

*Figure 8: Rectifier Circuit Setup*

*Figure 9: Signal Output Snapshot*

**Problem 2:**

*Figure 10: Calculated V_rms. Measured values are the same, just not recorded onto table.*

**Problem 3:**

We calculated the RMS values by taking the peak values taken by the oscilloscope and divided the value bu sqrt(2). The measured and calculated values match.

**Problem 4:**

*Figure 11: Output Voltages of rectifier in parallel with 1 micro Farad Capacitor*

**Problem 5:**

*Figure 12: Output voltages of rectifier in parallel with 100 micro Farad Capacitor*

The peak to peak voltage output is much lower, but the mean output is higher.

**Part C: Energy Harvesters**

**Problem 1:**

*Figure 13: Final output voltage at duration end using the tapping energy harvester.*

*Figure 14: Final output voltage at duration end using the flipping strain gauge energy harvester.*

**Problem 2:**With the tapping energy harvester, it seemed that with the initial tap, there was the highest amount of energy. At the start of every test, the energy read about or above 200 mV, however, as time went on and the test continued, the output went down. This is because the more we tapped out harvester, the faster the capacitor was filled which was decreasing the flow change in voltage through the capacitor.

With the flipping energy harvester was used, the more and longer we flipped the harvester over time the greater the amount of voltage that dropped through the capacitor.

**Problem 3:**There would be a back-flow of energy due to there not being a diode, which would make the output have negative troughs as well as positive peaks.

**Problem 4:**

close all;

clear all;

t = [125 80 0]; %1 Tap/sec

y = [71 91 0]; %4 tap/sec

f = [17 19 71]; %1 flip/sec

g = [105 205 220]; %4 flip/sec

d = [10 20 30];

plot(d,t,'r')

hold on

plot(d,y,':r')

hold on

plot(d,f,'b')

hold on

plot(d,g,':b')

xlabel('Seconds(s)')

ylabel('Output Voltage(mV)')

legend('1 Tap/Second','4 Tap/Second','1 Flip/Second','4 Flip/Second')

*Figure 15: Plotted information from Figures 13 and 14.*

In Part C your tapping strain gauge seemed to drop to zero after a while of tapping, we did notice some drops in voltage after time with our strain gauges too. I am not sure, I would have expected the voltage to climb up to a peak and then level out. Any thoughts?

ReplyDeleteWe noticed this. We think that with the tapping gauge, the capacitor filling is what caused the voltage to drop to zero, as there was no discharge, but with the flipping gauge, we believe the function of that allowed the capacitor to discharge and continue to intake voltage simultaneously.

DeleteFor your tables in question number 1 we got negative numbers for the minimum voltage. Do you know what is right? to get zeros or negative numbers? It is just confusing. For the last part our data are much higher, and we did not get zero for the 30 seconds tap we kept getting higher voltage to the end.

ReplyDeleteGood Job..

We believe that zero is appropriate value, but of course we are also subject to our own error. In reference to our 30 second measurement at 0, we believe it has to do with the capacitor filling but not discharging.

DeleteFor part A number 1 your voltage values were much higher then ours by a couple of times. You also didn't get a negative value for minimum voltage for which is weird. Your graph is a bit difficult to read.

ReplyDeleteWe only flipped in one direction, so that might be the reason for only positive input, and which graph?

DeleteHow did you guys get your graph's for the 1st question? They look very different from what my group got. We also had negative values as our minimums. Maybe your machine was set-up wasn't differently then mine.

ReplyDeleteWe had only flipped the flipping gauge in one direction, which might be why we only got positive values.

DeleteFor QA1 we got negative values for out low values. Also for part B Q4 & 5 we were not able to find peak to peak using our DMM. Lastly for part C we found that when we increased the frequency we got higher values for our outputs. I wonder what we did different?

ReplyDeleteWith q1 we only flipped the gauge in one direction, which might be why our values are all positive. The last part of C was confusing for us also. We think it might have something to do with out capacitor filling and then not discharging. However, when we first started those tests, they seemed to register a very high voltage then slowly die off.

DeleteFor Q1 in part A, your minimum and maximum values are different from ours, I don't know why you got zero for the minimum voltage but I think it should be a negative value because in the oscillscope plot, the line was below zero. For Q4 and Q5 in part B, we didn't get any value for the output effective voltage(pk-pk) when we measured it by using DMM, How did you set up your DMM to get this value?

ReplyDeleteIn your Part C, your values varied quite differently than our own. I believe this test itself was quite difficult for the human hand to give it the accuracy it needed. Good oscilloscope photos on Part A.

ReplyDelete