Lab1

Introduction

In this lab, you will learn and practice using common test equipment used when making circuits. Many of the terms may not be fully defined and their relationship may not be clear yet, such as voltage, current, and resistance, but those will be covered in more detail in a future lab.

Most of the test equipment is either on your desk or in the locked drawer on the north side of the desk (the one facing the Prototyping Labs). Talk to a TA or member of the Prototyping Labs staff to get a key. You will be asked for an ID in exchange for the key to make sure we get the key back when you are done.

We recommend you start at the Assignment section. As you walk through, you will encounter tasks you do not know how to do yet. Where appropriate, we have linked the correct section from the Skills to Learn articles, but you may have to dig through the articles to find what you are looking for.

For those who have not done any electronics work before, this can be a stressful lab, but if you take it one line at a time you will be ok. Ask for help from the TAs if you get stuck.

Skills to Learn

• How to Use a Power Supply
• How to Use a Multimeter (DMM)
• How to Use a Signal Generator
• How to Use an Oscilloscope

Assignment

Note: the lab write-up on Canvas is the ultimate source of truth for what should go into your report. Below are all of the items marked with a ">" in the original write-up, but please submit an issue if you find an discrepancies.

The corresponding assignment in the original document will be referenced in parentheses in line with this write-up. For example (DC Voltage: >) corresponds with the ">" on line labeled 5 in the DC Voltage section of the Canvas document.

Power Supply and Multimeter

1. Draw a diagram of the setup to read DC voltage with a multimeter (DC Voltage: >). The diagram should show which components are used, with lines showing how they are connected.
2. Set your power supply to 4.75 V and 1 A, then verify with your multimeter.
   1. Take a picture of your setup with the measured voltage (DC Voltage: >). Note: you may want to leave labels, such as sticky notes, in your pictures so you can reference them later in your write-up.
3. Draw a diagram of the setup to read DC current with a multimeter (DC Current: >).
4. Measure the DC current through a 1k ohm resistor, with your power supply set to 4.75 V and 1 A. Use the A plug on the multimeter, which is the one on the far left side.
   1. Take a picture of your results (DC Current: >).
   2. If the result is less than 400 mA, reconnect your probe to the mA/uA port and record again. Compare this result with the previous one (DC Current: >).

Oscilloscope and Signal Generator

1. Attach two 10X probes to your oscilloscope and calibrate them. Adjust the vertical position of each signal so that they overlap (superimposed). Both waves should fill the screen and show exactly one cycle.
   1. Take a picture of the waveform with your uncalibrated probes on the oscilloscope, then another once you have calibrated them (**Oscilloscope - Probe Setup: > **).
2. For the next setup, connect the signal generator and oscilloscope with a BNC to BNC connector. You will need to change the input on the oscilloscope back to 1X and change the load mode on the signal generator to "High Z". Set the signal generator to produce a ramp waveform at 100 kHz, 2.5 V peak-to-peak amplitude (difference between Vmax and Vmin), and a minimum voltage of 0.0 V. Visualize the signal using your oscilloscope with the horizontal scale set to 4 microseconds (us).
   1. Take a picture of the waveform (Signal Generator & Oscilloscope / Visualize a Signal >).
   2. Count the number of positive peaks on the screen and explain why you get the number you get (Signal Generator & Oscilloscope / Visualize a Signal >).
   3. Measure the peak-to-peak amplitude and minimum voltage. (Signal Generator & Oscilloscope / Visualize a Signal >)
   4. Set the horizontal scale to 1 microsecond and repeat the preceding 3 steps (Signal Generator & Oscilloscope / Visualize a Signal >).
3. For the last setup connect your signal generator and oscilloscope up across a 47 Ohm resistor. Remember to change the probe input back to 10X. On the signal generator, set the load to 47 Ohms and generate a ramp waveform (50/50), with peak-to-peak amplitude of 2.5 V, minimum voltage at 0.0V, and frequency set to 100kHz. Remember to turn the signal on. On the oscilloscope set the horizontal scale to 4 microseconds (us) per division.
   1. Take a screenshot of the wave on your oscilloscope (Signal Generator & Oscilloscope / Visualize a Signal >).
   2. Read and record the peak-to-peak amplitude and minimum voltage. (Signal Generator & Oscilloscope / Visualize a Signal >)
   3. Repeat the previous steps for each setting in the table below. You may need to change the horizontal scale to obtain a good visualization. Note: you just did W0 in the previous step. For each:
      1. Record the settings (horizontal scale, vertical scale) (Signal Generator / Waveforms >)
      2. Take a screenshot of the waveform (Signal Generator / Waveforms >)

Test Case	Waveform	Frequency	Peak to Peak Voltage	Vmin
W0	Ramp (50/50)	100 kHz	2.5 V	0.0 V
W1	Square	1.0 MHz	0.5 V	-.25 V
W2	Sine	1000 Hz	1.5 V	0.0V
W3	Ramp (50/50)	200 kHz	3.0 V	-1.5V
W4	Pulse: 5% on 95% off (duty)	1 MHz	3.0 V	0.0 V

Write-Up

The write-up (done outside of lab time) for this lab should use the following format:

1. Title page ([Report Template])
2. Introduction: ⅓ of a page describing the purpose and goals of this lab in your own words. Do not reproduce any material from this assignment document in any section of your write-up.
3. Results: Each line in the Assignment section indicates some data which must appear in your report. Separate each result or related set of results with a section header indicating what it is. For any numerical data or graph describe the meaning of the data.
4. Discussion and Conclusions: In ½ to 1 page, summarize the key learning points from the Results above.

Frequently Asked Questions

Q: I have set up the signal generator and connected it to the oscilloscope, but the signal seems flat.

A: Please check if the output of the signal generator is ‘On’. There is a yellow button ‘On/Off’ on the signal generator. It will light up if the output is ‘On’.

Q: I have signal wave(s) shown on the oscilloscope, but how do I measure the voltage?

A: You need to add measurement on the screen of oscilloscope. See the oscilloscope article.

Q: The waveform on the oscilloscope looks correct, but the amplitude (voltage) is 2 times larger / half than the expectation.

A: This is usually caused by the ‘load’ setting on your signal generator does not match your actual circuit setting. You may need to switch the ‘load’ mode on the signal generator. See the signal generator article for how to change the load.

Q: I changed the ‘load’ setting on the signal generator, but the output does not change.

A: This is a counter-intuitive performance of the signal generator. Once you change the ‘load’ mode, the signal generator will double or half the voltage value. Please double-check the voltage setting every time you change the ‘load’ mode.