Source: https://toolboom.com/en/articles-and-video/uni-t-ut81b-oscilloscope-review/
Timestamp: 2019-04-25 08:31:00+00:00

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Recently the measuring equipment market was added up by the devices that combine the features of several measuring devices. For instance, these are digital scope multimeters. UNI-T brand is well known for its high accuracy and reliable measuring equipment.
ToolBoom online store offers UNI-T UT81C multifunction measuring equipment, which is an upgraded version of UNI-T UT81B and has advanced technical specifications. It combines the functions of a full fledged multimeter and oscilloscope with analogue bandwidth up to 16 MHz. How did engineers manage to combine such a complicated device as an oscilloscope with a multimeter in one housing? What was the sacrifice for the sake of portability and what useful functions UNI-T UT81C possess?
UNI-T UT81C scope multimeter is a device of medium dimensions and light weight. That is why it is easy to keep it in hand. Round knob is used to turn on power and shift mode of the multimeter. There are separate buttons for oscilloscope control and universal buttons for measuring device control in two modes.
UNI-T UT81C device has a small fault: some buttons are not enough touch sensitive. You need to heavily press them if you want to make them work. At the same time measurement mode switch of the multimeter works quite well.
There is support, section for batteries and socket for connection to personal computer on the backside of UNI-T UT81C scope multimeter. Small rubber feet in the bottom of the case help fixing measuring device when it is placed on the slippery surface.
Probes of UNI-T UT81C scope multimeter are used for two working modes of the measuring device.
You can connect alligator clips to UNI-T UT81C probes, and it would be more comfortable for you to hold on pins on the electric schemes. They are equipped with rubber insulating jackets. It allows you to connect probes to alive terminals.
Control of handheld oscilloscope which also has functions of the multimeter significantly differs from control of the fixed device. First of all, there are less buttons on the control panels and menu is much more user friendly. However, you need to get used to control even of such a simple device.
Trigger is an important option of oscilloscope. This mode allows triggering signal according to the certain level of rising or falling edge. There are three trigger modes: automatic, normal and single.
Mode of saving oscillograms allows storing 10 wave forms into UNI-T UT81C scope multimeter memory, and subsequently display them on the screen. You cannot zoom saved signal, the only operation you can perform with it is movement along the time base.
Settings mode of the UNI-T UT81C measuring device (SET) allows adjusting function of automatic shutdown of power, sound signal during circuit continuity check and display parameters.
Auto Off — setting time of automatic shutdown of power within the range from 1 to 31 minutes.
BK Light — display brightness adjustment function. The level varies within the range from 1 to 31. After device shutdown this parameter is not saved.
Contrast — adjustment of display contrast ratio. Contrast ratio adjustment in relative units from 1 to 31. This parameters is also not saved after the device shutdown.
BEEP — option of turning on and off of the sound signal during the circuit continuity check. After power is shut down settings are not saved.
Display of UNI-T UT81C scope multimeter should be large enough for oscillogram display. In multimeter mode monochrome screen displays big figures which are quite visible in daylight and in dark places. Backlight is almost unnoticeable in a daylight and is perfectly visible in conditions of dim illumination.
UNI-T UT81C digital scope multimeter can be connected to personal computer. USB cable with optical coupler is used for connection.
The software for UNI-T UT81C oscilloscope multimeter may be easily installed on the computer. It allows registering readings of all measured units in the form of the table. Oscillograms are displayed in graphics format.
Interval between measurements can be set from 1 second up to several hours, you can also skip values repeated in sequence which allows you to significantly shorten the table. Number of measuring points is set from 1000 up to infinity. The program sets interval of 0.2 seconds between measurements by default.
Although the software to UNI-T UT81C scope multimeter is quite easy it helps following changes in the parameters of electric mains and electric circuits.
Signal frequency is 10 kHz, set amplitude is 2.5 V. Signal amplitude does not decrease during measuring.
Signal frequency is 100 kHz, set amplitude - 2.5 V. Signal amplitude does not decrease during measuring.
Signal frequency is 400 kHz, set amplitude - 2.5 V. Signal amplitude almost does not decrease during measuring.
Signal frequency is 1 MHz, set amplitude - 2.5 V. Amplitude decreased during measurement to 2.3 V.
Signal frequency is 5 MHz, set amplitude - 2.5 V. Amplitude decreased during measurement to 2.1 V.
Signal frequency is 8 MHz, set amplitude is 2.5 V.
Signal frequency is 16 MHz, set amplitude is 2.5 V.
The shape remains more or less square, and the amplitude almost does not decrease.
Signal frequency is 400 kHz, set amplitude is 2.5 V.
Signal amplitude during the measuring is 2.3 V, the shape is well preserved.
Signal frequency is 500 kHz, set amplitude is 2.5 V. Amplitude shown by the oscilloscope is approximately 2.3 V.
At a frequency of 1 MHz the amplitude decreases to 2.2 V.
At a frequency of 8 MHz the amplitude decreases to 2 V.
At a frequency of 16 MHz the amplitude decreases to 1.8 V.
This test showed that using common probes of the multimeter leads to incorrect work of the oscilloscope. The signal (specially meander) shape was distorted and lost its amplitude on the high frequencies. Only the application of coaxial cable allowed us to obtain good data. This problem can be solved by application of special adapters of oscilloscope probes (not included in the package).
Package of UNI-T UT81C scope multimeter is quite bright. It's a good choice for the gift.
We described basic functions of UNI-T UT81C scope multimeter. First of all it's a full fledged multimeter with wide measuring range of electric values. This device lacks a lot of useful options of full fledged oscilloscopes, however, UNI-T UT81C is good enough for simple tasks of detecting faults in electric and electronic circuits and also their adjustment. It's quite enough for working with signals up to 16 MHz.
Simple software of UNI-T UT81C measuring equipment allows registering measurements in easy format and further analysis of the obtained data.
You can adjust brightness and contrast ratio of the display, set time of automatic power shutdown in the settings menu.
UNI-T UT81C Digital Scope Multimeter is available at ToolBoom online store.

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