The purchase skills of secondhand oscilloscope
An oscilloscope can better measure the ac signal and view the waveform, becoming a powerful helper for radio enthusiasts. As a precision measuring instrument, the price of oscilloscope is much higher than that of ordinary multimeter, so its high price has been prohibitive for individuals with a small budget. With the development of science and technology, measurement requirements continue to climb, oscilloscope performance is also improving, many units have a lot of updated oscilloscopes into the secondary market, these secondary oscilloscopes become a good choice for personal radio enthusiasts.
What's the difference between the second-hand oscilloscope and the new oscilloscope?In fact, one is second-hand, one is new, there is no difference in use.Electronic products are different from mechanical products. There is no obvious difference between the old and new failure rate of electronic products. Even the failure rate of domestic new oscilloscopes is higher than that of imported second-hand oscilloscopes.
The quality of the oscilloscope imported second-hand oscilloscope is better, high brightness, bright spot is clear, compared to the domestic oscilloscope is much better.
Request when used oscillograph screen of choose and buy no aging phenomenon, very dark, can't concentrated all have a problem, and each action buttons, knobs can be normal use, no jamming, loose, the other is to create colour new better, because nice colour components are still in the life period, not aging, buy a master machine have you, components are fast to the grave, three days two head go wrong, will lose big.
Comparison between digital oscilloscope and analog oscilloscope
At the early stage of development, some characteristics of analog oscilloscope are not possessed by digital oscilloscope:
Operation is simple: all operations can be found on the panel, waveform response in a timely manner, digital oscilloscope is often a longer processing time.
High vertical resolution: continuous and infinite level, digital oscilloscope resolution is generally only 8 to 10 bits.
Data update fast: every second to capture hundreds of thousands of waveform, digital oscilloscope every second to capture dozens of waveform.
Real-time bandwidth and real-time display: the bandwidth of continuous waveform and single waveform is the same, the bandwidth of digital oscilloscope is closely related to the sampling rate, the sampling rate is not high need to use interpolation calculation, easy to confuse waveform.
In short, the analog oscilloscope provides the engineering and technical personnel with the waveform of seeing is believing.The visual nerve of the human eye is very sensitive in the five senses. The screen waveform is instantly reflected to the brain to make decisions, and subtle changes can be sensed.Therefore, the beginning of the analog oscilloscope by the user's welcome.
With the advent of digital oscilloscopes, people often ask if DSO can replace analog oscilloscopes.The answer depends entirely on the measurements to be made and the signals to be measured.In some cases, the advantages of DSO are obvious, while in other cases, the analog oscilloscope is better than the existing DSO.
The selection of oscilloscope
Since the invention of oscilloscope, it has been one of the most important and commonly used electronic testing tools. Due to the development of electronic technology, the ability of oscilloscope has been constantly improved. Its performance and price are also various, and the market is uneven.
You know what to look at with an oscilloscope?What is the typical performance of the signal to be captured and observed?Does the signal have complex properties?Is the signal a repeat signal or a single signal?How many signals are you going to display at the same time?
What is the bandwidth of the signal transition process, or the rise time to be measured?What signal characteristics are intended to trigger short pulse, pulse width, narrow pulse, etc.?
The traditional view thinks that the analog oscilloscope has the familiar panel control, the price is low, therefore always thinks that the analog oscilloscope "USES conveniently".However, with the increasing speed and price of A/D converter year by year, as well as the increasing measuring capacity and virtually unlimited functions of digital oscilloscope, digital oscilloscope has become the leader.
Bandwidth is generally defined as the frequency when the amplitude of sinusoidal input signal attenuates to -3db, that is, 70.7%. Bandwidth determines the basic measuring ability of oscilloscope to signal.With the increase of the signal frequency, the oscilloscope's ability to display the signal accurately will decline, if there is not enough bandwidth, the oscilloscope will not be able to distinguish the high-frequency change.The amplitude will be distorted, the edges will disappear, and the details will be lost.Without sufficient bandwidth, all the properties of the signal obtained, such as ringing and ringing, are meaningless.
It is a tedious process to comprehensively evaluate the performance index of a second-hand oscilloscope, which can only be completed by metrological engineers using professional calibration instruments.
Individual users with limited conditions can only roughly judge the quality of second-hand oscilloscope by observing its calibration signal. The calibration signal is usually 1KHz square wave, and even if it can be displayed normally, it only means that the scanning time and vertical deflection of the oscilloscope are generally normal, and there is a good frequency response within the bandwidth of 5KHz.As for whether the indicators such as bandwidth/sensitivity are up to standard, signal sources should be used for inspection.