What is the best cheap oscilloscope? First of all, make sure that the product you are going to buy is manufactured by a trustworthy company with a decent customer service and maintenance department. As for the most important characteristics, the first thing you need to consider is the minimum sample rate. This value must be twice the highest frequency. Then, look at a maximum input voltage. All scopes are safety-rated with a maximum input voltage which should be specified in the probe. Choose a probe that is rated for a higher voltage than the signal being tested. The most frequently used 10:1 or 20:1 high Z passive probes and bandwidth up to 600 MHz are adequate to view up to approximately 300V. Another feature to consider is the number of channels. The more channels the oscilloscope has, the more circuit points you can measure at a time. We believe that Rigol DS1054Z Digital Oscilloscope meets these criteria best.
An oscilloscope allows you to test circuitry for electrical current competence and safety. It is “as accurate as the data going into it”. Recorded voltage patterns (over time) can tell you the status of power surges or why your ignition doesn’t seem to be working.
Older cathode ray oscilloscopes (CRO) use electron beams to detect changes in an electrical signal and generate waveform images that are displayed on its screen. Today’s digital storage oscilloscopes (DSO) display graphic output of sound, voltage or vibration signals generated over time. Software programs control and produce signal sweep rate, deflections, analysis, storage and other features.
The Main Characteristics of Oscilloscopes
Oscilloscopes measure electrical signals generated by pressure, stress, sound, light or heat. They are used in medical, telecommunications, scientific labs and automotive industries to analyze equipment, maintain electronics monitor medical, science, and engineering laboratory processes and procedures. Oscilloscopes offer numerous features and functions. Regardless of what they are being used for or their cost, these scopes should be easy to use, accurate and deliver maximum performance.
Maximum (real-time) sample rate
Input signals are sampled at a high frequency (sample rate) and converted into a digital format. Sample rates define how many times per second (GS/s) a signal is read. It shows how much waveform data the scope is able to capture. The Nyquist “five times rule” is used to ensure signals are accurately reconstructed. According to this “rule” the minimum sample rate must be twice the highest frequency, or 5-times as fast as what is minimally acceptable. The minimum sample rate suffices if you are observing slow-changing signals over a long period of time.
Real-time sampling challenges the scope’s accuracy. High-frequency events that occur only once must be sampled when they occur. Basic oscilloscopes typically have a maximum sample rate of 1-2 GS/s. Mid-level scopes are faster with sample rates of 5-10 GS/s. Faster sampling tends to produce a more representative signal since less information is lost.
Horizontal and vertical sensitivity range
A waveform with voltage level appears the vertical (Y axis) and the timebase on the horizontal (X axis). The screen is divided into horizontal and vertical divisions that indicate waveform calibrations.
Horizontal sensitivity control
Horizontal controls control the time scale and position. Horizontal sensitivity control is found on high end scopes. The control makes adjustments for external horizontal inputs only when the scope is in X-Y mode and the internal horizontal sweep is off.
Vertical sensitivity control
Vertical sensitivity shows how much the vertical amplifier can strengthen a weak signal. It is measured in millivolts (mV/div) and may be adjusted to set the voltage/div. A basic oscilloscope that detects minimal voltage 1-2 mV/vertical screen division may have a reduced sensitivity of 5 V/div. The scope may have a switch or knobs to calibrate vertical deflection sensitivity when there is a wide range of input amplitudes.
Maximum input voltage
The oscilloscope is a voltage-measuring device. Voltage (the amount of electric potential between two points in a circuit or from the maximum point of a signal to its minimum point) is indicated by the number of divisions in the waveform span on the scope’s vertical scale.
Input voltage includes both AC and DC. All scopes are safety rated with a maximum input voltage (highest voltage) which should be specified in the probe. Active probes withstand a few tons of volts. Passive probes can sustain hundreds of volts, but be aware that the scope’s input capacitance is within the probe’s compensation range or you risk receiving an incorrectly compensated square wave signal. The scope may become damaged if the signal exceeds the voltage.
Choose a probe that is rated for a higher voltage than the signal being tested. The most frequently used 10:1 or 20:1 high Z passive probes and bandwidth up to 600 MHz are adequate to view up to approx. 300V. These are standard with most scopes less than 1 GHz.
Timebase is the combined sample frequency and recorded time (test duration). It is expressed in seconds/div. Timebase controls allows you to choose the horizontal speed and create trace (sweep). The sweep speed is expressed in time/graticule div. Most scopes allow you to control a wide range of sweep speeds.
Number of channels
The more channels the oscilloscope has, the more circuit points you can simultaneously measure. Most scopes display several signals on the screen at once for comparison. Each signal goes into its own channel although some scopes share sampling between channels. In this instance, be aware that the number of channels turned on at the same time can reduce the sample rate.
The number of channels you need depends on your applications. Two and four channels are common and allow you to compare waveform signal timings. Two channels are adequate for a hobbyist. Eight, sixteen, or more channels are needed for a digital system that debugs using parallel data. Mixed domain oscilloscopes may have both analog and digital channels. Digital timing channels show (high-low) bus waveforms. RF input measures high frequency.
Measurement system noise consists of a variety of scope noises and probes that overlay the signal. Applications and high-energy and power transducers, sensors, physics, integrity, and high-speed digital designs produce conditions that obscure small signals. The input amplifier, buffer circuits, probe amplifier and vertical scale attenuator contribute to measurement system noise.
Noise reduction recommendations: A null measurement may be performed to ensure the scope, probe and connection method are appropriate for the measurement activity. The pre-set bandwidth may be adjusted to limit the used bandwidth only to the amount needed to complete the measurement activity. Expand the signal so it fills the entire screen. Some scopes have a high resolution option (mode) that can effectively be used non-repetitive signals.
Oscilloscope Comparison: Rigol Vs Quimat
1. Rigol DS1054Z Digital Oscilloscope
The Rigol DS1054Z model is the best-selling, entry-level digital oscilloscope for schools, businesses, and the hobbyist. Rigol is a maker of reliable, high-quality scopes. This compact scope is a lightweight 6.6 lbs., which makes is conveniently portable. Its integrated channel, deep memory and decoding functions allow extensive analysis and performance.
This oscilloscope has a 50 MHz analog bandwidth for display accuracy. Its four (separate) analog channels make it possible to simultaneously track several voltage sources. Its higher 1 GS/s sampling rate ensures accurate recognition of alternating events. Innovative UltraVision technology includes 12 Mpts of deep memory, which comes standard and which can be upgraded to 24 Mpts. It also includes a 30,000 wfms/s waveform capture rate and real time record/replay waveform quick-focus option. It also includes 4 RP2200 150 MHz Passive High Z probes.
The device also features a large, high resolution 7-in., WVGA 800 x 480 TFT screen that provides multilevel intensity grading displays and offers greater readability. Its integrated (advanced) system of formulas calculates complex signals. It also includes a USB connector (thumb drive host and device) and LAN (LXI) for an Ethernet connection and Aux (TrigOut / PassFail) Output. Advance triggering and serial bus options may be purchased.
This oscilloscope is CE and CSA safety certified.
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2. Quimat Updated 2.4" TFT Digital Oscilloscope Kit
This updated, handheld Quimat (Q15001) digital oscilloscope comes fully-assembled (unlike similar DIY PART products). The Q15001 is a DSO138 model upgrade that includes a higher- and wider-sensitivity DSO shell. Sensitivity has been extended in both directions to 5mV/div and 20V/div with a sensitivity error less than 5%. The Q15001 is a lightweight 100 g. device that runs on a 9V battery, which makes it a conveniently useful portable technician’s tool.
Its single analog channel has a maximum bandwidth of 200 KHz. The channel sits on a board apart from most user install parts to ensure adequate separation between analog and digital circuits. It has a 50Vpk maximum input voltage and input impedance of 1M ohm. This upgrade has a maximum 1M sa/sec sample rate and includes “Auto”, “Normal” and “Single” rising/falling edge trigger modes in fixed ½ buffer-size position.
The Q15001 also features a high-quality multicolored 2.4-in., 320 x 240 TFT, 12-bit resolution LCD screen that displays an exceptional amount of graphic information. The display is mounted on the main board with the MCU to avoid interboard pinheaders. Sensitivity/vertical position, timebase/horizontal position, trigger and Hold/Run buttons, and a rotary “Adjustment” dial are conveniently located on the device’s face. The power switch and power supply connector port are on the underside of the device and BNC signal input connector, test signal output and AC/DC/Ground coupling switch are located on the top of the device.
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How Do Expensive And Cheap Oscilloscopes Differ?
Different features drive the cost of an oscilloscope. “Cheap” oscilloscopes are not necessarily low-quality machines. Device and screen size, channels and sample rate and other features add to the model’s overall price. The scope’s bandwidth may be the main cost driver. And as a general rule, the sample rate should also be 10x the bandwidth.
An entry-level digital oscilloscope with basic features and a narrow bandwidth (i.e.: 200 MHz) is less expensive costing only a few hundred dollars (i.e.: $250). DIY toy-style oscilloscopes and kits are cheaper and suffice for basic circuit analysis.
On the other hand, a high-quality, multi-featured and multi-optioned oscilloscope that has a bandwidth of 1 GHz will cost thousands. Extreme high-end, high bandwidth multi-functional models (5+GHz) that offer several equipment operations in a single scope (i.e.: variety of analyzers, waveform generator, digital voltmeter and counter, etc.) can cost tens of thousands of dollars.
Another primary consideration is the reliability of the measurement probe. An oscilloscope is as accurate as the data it receives. A poor probe tip does not guarantee the signal’s accuracy when capturing readings.
When do you need an expensive oscilloscope?
It is important to know what measurements your job or project requires and what options your oscilloscope should have to ensure you obtain accurate and consistent measures. Consider not only the size and bandwidth when choosing the best oscilloscope for your job, but also its sample rate, rise time, channel density and compatible probes.
Beginners and hobbyists should start with less expensive equipment. Older used bench scopes (Rigol, Owon, etc.) might serve your purpose. A 50 -100 MHz scope with few channels is a good low-end machine, although many have lower bandwidth front ends or other issues. “Soundcard” type oscilloscopes operate as input networks and feed signals into a PC soundcard. These are sufficient DIY project scopes, but you will likely want a second more powerful (upgraded) machine as your project needs increase.
10 Best-Selling Oscilloscope Comparative Table
FAQ: What and How an Oscilloscope Measures:
Can an oscilloscope measure current?
It can measure how much of a signal is AC (alternating current) or DC (direct current) using a current probe or by measuring voltage drop across a shunt resistor.
Can an oscilloscope measure the frequency?
Most oscilloscopes automatically measure the frequency of one part of the signal relative to other parts.
Can an oscilloscope measure AC / DC voltage?
It measures the signal’s time and voltage values. Or measure DC voltage (manually) by ‘counting’ the vertical reticules and multiplying by the volts/division.
Can an oscilloscope measure capacitance?
It does not measure direct capacitance. It can measure a time constant that can be used to find the actual (electrical system) capacitance with aid of an arbitrary function generator.
Can an oscilloscope measure resistance?
An Ohmmeter or digital multi-meter is a better instrument for measuring resistance.
Can an oscilloscope measure inductance?
It measures inductance with the aid of a function generator (the uncertainty value is 3-5%).
Can an oscilloscope display sound waves?
Its display shows if a component is distorting the signal.
What is an Oscilloscope? Oscilloscopes are a specialized piece of equipment used to visualize the waveforms produced by electric signals, RF (radio) signals, and to analyze soundwaves. Everyone has seen an oscilloscope, if nowhere else, then on television and in movies, drawing warbling rings or wobbling wavy lines on a small CRT screen.
Oscilloscopes are based around the concept of signals travelling in the form of waves, or a rising/falling pattern (peaks and valleys). This waveform principle is used to encode data via electrical and radio signals, to carry analog radio signals, and defines the nature of voltage and frequency in electrical components.
Oscilloscopes are generally used as a problem-solving tool to test the flow of voltage through various sections of a circuit board or section of an integrated circuit. Modern oscilloscopes have an onboard postprocessing computer which can aid in visualizing if the wave seen matches the wave expected, and the old CRT display system has long since been replaced by a TFT or LCD screen in most cases, though CRT versions do still exist.
If you like to work on computers or other electronics projects, an oscilloscope can help you be sure the right signal and voltage level is being sent and received by various components of your apparatus, with more intuitive data than a simple ohmmeter or voltage tester can provide.