The resultant signal should be an 800 mV sine
wave with minimal offset.
Using the inverting gain circuit shown in
Figure 8, amplify the output of the differential amplifier circuitby an additional factor of ten. This can be done with another
op-amp and a 10 k ohm resistor and a 30 k ohm resistor. Theresultant output signal should have a mean of zero and amplitude of
~2.4 V. Adjust the potentiometer to remove any offset.
Part 7: low-pass filtering
A low pass filter can be used to attenuate
high-frequency noise in an analog signal and to minimize the
portion of the signal that will be aliased. Later in this lab, youwill see a demonstration of the damaging effects of
aliasing.
7.1 build an active low-pass filter
Build the first-order filter shown in Figure 9 with R1 = R2 =
10 k ohm and C2 = 0.1 micro F. First order filters are so-called becausetheir dynamics are modeled by first-order differential
equations.
Connect the output of the circuit to Channel 1 on your DAQ
system.
The filter’s time constant is equal to R2C2. Calculate values
for the cut-off frequency and the time constant.
7.3 modifying existing vi to measure magnitude ratio
By measuring the magnitude of the input and
output of a filter, you can determine the how much the filterattenuates the signal.
Delete the Amplitude and Frequency constants from the Block
Diagram.
Hold Ctrl as you drag the Tone Measurements icon to make a
copy.
Place a Split Signals icon to the left of the Tone
icons.
Place a Divide function to the right of the Tone
icons.
Create a numeric indicator at the x/y output terminal of the
Divide function.
Rename the numeric indicator Magnitude Ratio. (The Magnitude
Ratio represents the output amplitude divided by the inputamplitude.)
Wire the Block Diagram as shown in Figure 10.
Save the VI.
7.2 testing a filter
We expect that the filter will allow
frequencies below the cut-off frequency to "pass", and willattenuate signals at higher frequencies. The Magnitude Ratio will
be recorded as the output magnitude divided by the inputmagnitude.
Connect the signal going into your filter to Channel 0 of
module 1 of the SCXI.
Connect the signal coming out of your filter to Channel 1 of
module 1 of the SCXI.
Input a 1 V sine wave with zero offset into the low-pass
filter circuit.
Starting with a frequency of about 10 Hz, slowly increase the
frequency of the input signal. What happens to the outputsignal?
Increase frequencies to 2 kHz.
Using the table below, determine the magnitude ratio at
several frequencies.
Table 1: Magnitude Ratio Data for First-Order
Low-Pass Filter (Active)
frequency (Hz)
Input magnitude (V)
Output magnitude (V)
Magnitude ratio
10
1V
18
1V
32
1V
58
1V
110
1V
190
1V
340
1V
620
1V
1100
1V
2000
1V
Using Excel, plot the following two sets of data on a single
log-log chart.
Calculated magnitude ratio vs. frequency.
Measured magnitude ratio vs. frequency
Do the magnitude ratio and phase difference
between the input and output behave as you would expect?
Questions & Answers
anyone know any internet site where one can find nanotechnology papers?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?