The output voltage between terminals 1 and 2 can be calculated by the voltage division formula shown in Figure 6. To adjust the input voltage, a voltage source is connected to the terminals 1 and 3 as shown in Figure 5. Variable resistors allow you to adjust the value of voltage by changing the resistance and keeping current constant.
Other voltage readings using multimeters need to be taken as well of course. The oscilloscope will show the effect of the variable input, the output being a square wave varying from 0V (when the input is above 1.25V) to 5V (when the input is below 1.25V). Adjust your design for it if you need to. The far right resistor is just a pull-up resistor, typically kohms values as well. I would recommend using in the kohms values. This resistor value is what you will have to calculate (this is a design issue). This 1.25V will be across the bottom resistor which by the way is typical in a voltage divider situation. The directions say that you need 1.25V (out of that 5V dc). Lab 2 hints For the 2 resistors on the left, they are in a voltage divider configuration. How does your measured -3dB frequency (fc) compare to your design critical frequency? Give some reasons why it is different. Does your circuit attenuate the signal at high frequencies? What is the attenuation at 10kHz?Ģ. What is this frequency called?Ĭreate a plot of your data (you can do this easily in Excel) and copy and paste the plot into your report.ġ. What is the frequency of the signal? That is your critical frequency. Using your simulation, change the frequency of the input voltage until the output voltage is that associated with your 3dB point. Given the output voltage at dc, what is the voltage 3dB down? In other words, what is the output voltage at the 3dB point? You should calculate this. Be sure to capture several screenshots of the Tektronix virtual scope. Measure additional frequency points in order to get a nice set of data for the drop off.
Use the multifunction generator for the input and use both channels of the Tektronix virtual scope to display the input and output voltages.Ĭreate a table of your input and output voltage at dc, 250 Hz, 500Hz, 750Hz, 1kHz, 5kHz, 10kHz, 50kHz, 100kHz. Use the tolerances which you specified in your design. Be sure to use standard resistor and capacitor values and specify the tolerance. What kind of RC filter do you need? Design the RC filter. In order to not amplify that noise through your instrumentation system, you decide to use a RC filter with a cutoff frequency (critical frequency, fc) of 1kHz after the sensor and before the amplification.Ī. You are taking a measurement of a signal from a sensor with high frequency noise.
W1 Lab: Introduction to Process Control Labġ.