Oscilloscopes are an important tool to be used in any electrical engineer’s lab. You can view the electric signals as they vary over a period of time which can be critical in diagnosing your 555 timer circuit as to why it isn’t blinking correctly or why the noise maker is not reaching to its maximum annoyance levels.
Basics of an Oscilloscope
The main function of the cheap oscilloscope is to graph an electric signal as it varies over a period of time. Most often the oscilloscope produces a two-dimensional graph having time on the x-axis and voltage on the y-axis.
The controls that are surrounding the screen of the oscilloscope allows you to adjust the scale of the graph both horizontally and vertically and also allows you to zoom in and zoom out of the signal. There are other controls on the cheap oscilloscope that helps to set the trigger and also focuses and stabilizes the display.
The measurement was done by the Oscilloscope
Other than fundamental tools, there are oscilloscopes having measurement tools that help to quantify the frequency, amplitude, and other characteristics of the waveform. Hence, a cheap oscilloscope can measure both tile-based as well as voltage-based characteristics.
- Frequency and period: frequency is defined as the number of times the waveform repeats per second. The period is the reciprocal of frequency such that it is the number of seconds taken by each waveform to repeat itself. The maximum frequency an oscilloscope can measure varies, but it is often in the 100s of MHz range.
- Duty cycle: This refers to the percentage of a period that a wave is either a positive or negative duty cycles. It is a ratio that indicates how long a signal is ‘on’ versus how long it is ‘off’ during each period.
- Rise and fall time: The signals cannot instantaneously go from 0V to 5V, but they can smoothly take a rise. The time is taken, or duration of a wave going from low point to high point is called as a rise time and fall time measures just the opposite. This is an important characteristic when considering how quickly a circuit responds to the signals.
- Amplitude: It is a measure of the magnitude of a signal. There are a variety of measurements including peak-to-peak amplitude which is used to measure the absolute difference between the high as well as low voltage points of a signal. Peak amplitude, on the other hand, is used to measure how high or low a signal is obtained past 0V.
- Maximum and minimum voltages: the oscilloscope is used to measure exactly how high and low the voltage of the signal gets.
- Mean and average voltages: The cheap oscilloscopes are used to calculate the average or mean of the signal, and also can measure the average of the signal’s minimum and maximum voltage.
Use of Oscilloscope
The oscilloscope can be sued in a variety of troubleshooting situations such as:
- In order to determine the frequency as well as the amplitude of a signal, which is critical in debugging a circuit’s input, output, and internal systems.
- To identify the amount of noise is there in your circuit.
- To identify the shape of the wave such as sine, square, saw-tooth, triangle, complex, etc.
- To quantify the phase differences between the two different signals.
How to Measure Voltage Using an Oscilloscope?
The oscilloscope is used to measure the electrical signal which is displayed on a graph of plots with voltage vs. time was known as a waveform. You need just to measure the voltage, rest values are obtained by calculation. Voltage is the amount of electric potential between the two points in a circuit. To measure the voltage with your cheap oscilloscope will provide basic information about the signal. Normally, the oscilloscope has fixed input range, but this can be easily increased or changed with the use of simple potential divider circuit. Let us focus on how to measure the voltage with an oscilloscope.
- Step 1: turn on your oscilloscope and then push the default setup from the front panel key.
- Step 2: Plug in the probe into channel 1. If you have a probe with a clip or any other mechanism which will prevent you from having to hold it to the wire, it will be easier to manage the oscilloscope.
- Step 3: Then find reliable grounding point and connect the ground clip to it.
- Step 4: Then connect the tip of the probe to the signal which you want to measure.
- Step 5: The oscilloscope will then measure the voltage of your signal and display the signal as it changes over the time period. If you are unable to see the complete signal and then press the ‘Auto Scale’ front panel key to center and then scale your waveform.
- Step 6: Then you can use the vertical and horizontal knobs to adjust further the signal and how it is displayed on the screen. These knobs are used to zoom in and zoom out as well as adjust through right, left, up as well as down. In order to get the best measurement with your cheap oscilloscope make sure that the signal is spanning most of the vertical scale.
- Step 7: The basic way or method to calculate the voltage is to count the number of divisions from top to bottom of the signal and then multiply this by the vertical scale, i.e. volts/division. Further, note that the divisions are labeled in volts on y-axis so that you can easily calculate the voltage of the signal using the labels.
There are other types of oscilloscopes that have features that eliminate the need for counting the marks for divisions. You can also try any one of the following methods to measure the voltage with an oscilloscope quickly:
- You can use the on-screen cursors to take the voltage measurement between the two points, i.e. from top and bottom of the waveform.
- You can even use the peak-to-peak measurement.
- You can even use the built-in DVM.