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The FNIRSI DSO520 is an upgrade of the DSO152 handheld oscilloscope from the same manufacturer. The improvements include a bandwidth of up to 10 MHz, a sample rate of 48 MSa/s and a built-in signal generator capable of up to 50 kHz. |
Introducing the FNIRSI DSO510
The DSO510 handheld oscilloscope
Measuring 99.0 mm by 68.3 mm by 19.5 mm, the DSO510 fits comfortably in your hand and slips easily into your pocket. However, thanks to a fold-out stand, you can just as easily place the device on your workbench at an optimal viewing angle. The DSO510 has a built-in lithium battery with a capacity of 1,000 mAh, providing an average operating time of four hours.
The DSO510 features an AUTO mode, which automatically displays a few periods of the input signal stably on the screen. The built-in function generator provides thirteen different waveforms up to 50 kHz and up to 3.0 Vpeak-to-peak.
You can save screen images to the internal memory at the touch of a button and then copy them to your PC via the USB link.
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The DSO5210 is a true handheld oscilloscope. (© 2026 Jos Verstraten) |
The packaging of the DSO510
The DSO510 comes in a well-made box. A cardboard insert ensures that any minor dents in the packaging during transport cannot damage the device. The accessories are contained in a second cardboard box inside the main box.
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| The packaging of the DSO510. (© 2026 Jos Verstraten) |
What's included with the DSO510
In addition to the DSO510, the box contains:
- A compact Chinese/English manual.
- A carrying strap.
- A standard oscilloscope test lead with a BNC connector.
- A BNC to MCX adapter.
- A cable with crocodile clips and an MCX connector.
- A USB-C to USB-A charging and data cable.
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The accessories included. (© ixbt.site) |
The manufacturer FNIRSI
FNIRSI is a Chinese manufacturer of affordable electronic measuring instruments for hobbyists and students. The company's official name is 'Shenzhen FNIRSI Technology Co., Ltd.' and it is based in Shenzhen. The products are known for their original, modern design and their often combined functions, such as an oscilloscope with a function generator or a component tester with a multimeter. Unfortunately, the company is also known for the highly optimistic specifications of its equipment. In addition to the official '-3 dB bandwidth', there is also a concept known as 'Chinese bandwidth'!
Suppliers and price
Almost all Chinese mail-order companies stock FNIRSI products, and even a company like Eleshop has some of these products in its range. You can also order this oscilloscope via eBay and Amazon.
A few prices as of 23 May 2026:
- Banggood: € 32.77
- AliExpress: € 31.19
- Eleshop: € 49.95
- Amazon: € 37.91
The appearance of the DSO510
The photo below shows the main views of the DSO510. On the rear, you can see the two MCX connectors for the oscilloscope (DSO) and the function generator (DDS). Next to these is a clip with the 1 kHz calibration signal for the probe and a small button with three positions. When pressed, this button acts as the standard 'OK' key and the cursor keys '◄' and '►'.
On the left-hand side is the USB-C connector for charging the internal battery and for data transfer to your PC. A two-colour LED indicates the battery's charge status. Through a small hole, you can use the end of a paperclip to reset the hardware if it should freeze.
In the bottom left-hand corner of the front panel is the 'ON/OFF' switch. On the right are five push-buttons used to operate the device.
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| The three main views of the DSO510. (© 2026 Jos Verstraten) |
Oscilloscope specifications
- Analogue bandwidth: 10 MHz
- Sampling rate: 48 Ms/s
- Vertical sensitivity: 10 mV/div ~ 10 V/div (1-2-5 steps)
- Maximum input voltage: 40 Vpeak-to-peak
- Coupling: AC ~ DC
- Calibration output: 1 kHz square wave ~ 50% duty cycle ~ 3.3 Vpeak-to-peak
- Time base: 50 ns/div ~ 20 s/div (1-2-5 steps)
- Trigger mode: Auto ~ Normal ~ Single
- Trigger start: negative or positive edge
Note: The 1-2-5 division of the time base is disrupted in the fastest settings, as 200 ns/div does not exist but is 250 ns/div.
Specifications of the function generator
- Frequency range: 0.001 Hz to 50.00 kHz
- Peak-to-peak voltage: 0.1 V to 3.0 V
- Duty cycle: 1% to 100%
- Waveforms: 13
General specifications
- Display: 2.8 inches ~ 320 x 240 pixels
- USB charging: 5 V ~ 1 A
- Battery: 1,000 mAh
- Dimensions: 99.0 mm x 68.3 mm x 19.5 mm
- Weight: 104 g
The manual
The manual supplied is 2x14 pages long and provides a fairly brief description, in both Chinese and English, of the DSO510's functions and operation. The description of how to use it could have been much better!
You can browse through this manual on our account on the 'Internet Archive':
The electronics in the DSO510
Everything on a single PCB
As is customary nowadays, all the electronics are on a single PCB that fills the entire housing. The microcontroller's part number has been made illegible. The other chips are, however, identifiable. We find the following on the PCB:
- 1 x 74HC40510, an 8-channel analogue multiplexer and demultiplexer.
- 1 x 3PA1030, a 10 bit ADC from 3PEAK.
- 1 x TC4056A, a lithium-ion battery charger and controller.
- 1 x GS8092, a dual rail-to-rail output voltage feedback amplifier.
- 1 x 25Q64, an 8 megabyte serial flash memory chip.
- 3 x voltage regulators for 3.3 V and ±5.0 V.
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| The electronics in the DSO510. (© 2026 Jos Verstraten) |
Setting up the DSO510
Note
We find the operation of this oscilloscope anything but intuitive! You really do need to spend some time getting to grips with it, but in practice it operates smoothly once you get used to the sequence of steps required.
Start-up
After pressing the 'ON/OFF' button at the bottom left of the front panel, the DSO510 starts up in oscilloscope or function generator mode. You can set this yourself (read on).
The main menu
To access this, press and hold the 'OK' button (the three-position switch on the rear panel) for more than one second. By moving this button to the left or right, you can select one of the three operating modes:
- Oscilloscope
- Signal Generator
- Settings
You activate the selected mode by pressing the 'OK' button again briefly.
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| The three operating modes of the DSO510. (© 2026 Jos Verstraten) |
The 'Settings' menu
This menu has eight options that you select using the '▼' and '▲' buttons. You activate an option by pressing the 'OK' button. You can then use the '▼' and '▲' buttons to select a parameter from the option. Use '◄' and '►' to decrease or increase the value of a parameter. Confirm with 'OK'.
After pressing the 'MODE' button, you can use '▼' and '▲' to select another option from this menu.
- Language
Selects the interface language, Chinese or English. - Sound and light
Adjusts the screen brightness and beep volume. - Startup on Boot
You can choose whether the DSO510 starts up as an oscilloscope or a function generator. - Theme
Selects blue or yellow as the colour for the options selected in the menus. - Auto Shutdown
You can choose the time interval for the device to switch off automatically: never, 15, 30 or 60 minutes. - USB Sharing
Select this option if you wish to establish a connection with your PC. - About
Displays the software version number. Our unit has version V1.0.4. - Factory Reset
Resets all options to their factory settings.
The 'Signal Generator' menu
After opening this menu, you can use the '▼' and '▲' buttons to select one of the thirteen signal waveforms. Confirm your selection by pressing 'OK'. You can then set the frequency, duty cycle and amplitude of the output signal. This menu is operated in the same way as described for the 'Settings' menu.
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| The menu for configuring the generator. (© 2026 Jos Verstraten) |
The 'Oscilloscope' menu
If you select the 'Oscilloscope' option in the main menu and confirm with 'OK', the DSO510 will immediately display the oscilloscope screen and you can start measuring. To adjust the oscilloscope settings, press and hold the 'MODE' button for more than one second. This 'Oscilloscope' menu has four options:
- Waveform
- Parameter
- Persistence
- Image
The 'Waveform' sub-menu
In this sub-menu, you can configure key oscilloscope settings
- Coupling: 'AC' or 'DC'.
- Probe: 'X1' or 'X10'.
- Mode: Set the trigger mode to 'Normal', 'Auto' or 'Single'.
- Edge: Triggering on the rising or falling edge of the signal.
In the 'X10' mode, the numerical indication of the measured voltage is increased by a factor of ten to compensate for the probe's attenuation.
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| The 'Waveform' sub-menu. (© 2026 Jos Verstraten) |
The 'Parameter' sub-menu
In this sub-menu, you can select which numerical data from the measured signal you wish to see on the screen. You can choose from twelve parameters, such as frequency, period, duty cycle, pulse widths, amplitude, rms value, average value and maximum peak values. Use 'A-on' or 'A-off' to switch the numerical display on or off. Unfortunately, the software does not remember your choice. If you switch from 'A-on' to 'A-off' and then back to 'A-on', all twelve parameters are switched on again and you have to switch off the unwanted ones one by one. A very irritating and incomprehensible choice by the software developers!
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| The 'Parameter' sub-menu. (© 2026 Jos Verstraten) |
The 'Persistence' sub-menu
In this menu, you can set the duration of the trace's afterglow on the oscilloscope screen to off, 500 ms, 1 s or infinite.
The 'Image' sub-menu
This sub-menu provides an overview of all the screen captures you have saved in the DSO510's memory. As you can see, these screen captures are saved as .BMP files. Using the '▼' and '▲' buttons, you can select one which will appear on the screen after pressing 'OK'. Using the '◄' and '►' buttons, you can display all saved screen dumps one after the other on the screen. If you wish to return to the real-time screen, you must press the 'OK' button twice.
You cannot delete the saved images via this menu. This can only be done, after establishing a connection with your PC, via Windows File Explorer.
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| The 'Image' sub-menu. (© 2026 Jos Verstraten) |
Working with the DSO510
The DSO510 display
On the top line of the display, you see, from left to right:
- The waveform generated by the oscillator.
- The time base setting.
- 'RUN' or 'STOP' (freeze the display)
- The function of the 'MODE' button (see below).
- The battery status.
The arrow to the left of the waveform indicates the zero level; the arrow to the right indicates the trigger level.
On the bottom line, you see, from left to right:
- The sensitivity setting.
- The trigger mode.
- The trigger edge.
- The '1X' or '10X' setting for probe compensation.
- 'AC' or 'DC' coupling of the input signal.
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| The oscilloscope screen. (© 2026 Jos Verstraten) |
From 'AUTO' to manual control
When you select the oscilloscope function, the DSO510 enters 'AUTO' mode, in which the software calculates the most suitable settings for sensitivity and time base. If you wish to switch to manual adjustment of these two parameters, you can do so using the 'MODE' button and the four cursor keys. Press this button until 'V H' appears on the top line of the screen. You can then use the '▼' and '▲' buttons to set the sensitivity, and the '◄' and '►' buttons to adjust the time base.
Adjusting the image position
Press the 'MODE' button until the top line of the screen displays '► ▼'. You can now use the cursor keys to adjust the image position:
- '▼' and '▲' keys: move the image up and down
- '◄' and '►' keys: move the image left or right.
Setting the trigger level
Press the 'MODE' button until you see '◄ ▼' on the top line of the screen.
- '▼' and '▲' keys: set the trigger level.
Saving and copying screen dumps
It's very simple. Press and hold the 'RUN' button for more than one second; the text 'saving… xxx.bmp' will appear on the screen. Using the 'USB Sharing' option in the main menu, you can view the contents of the memory in Windows 'File Explorer'. You will, of course, need to connect both devices using a USB data cable with USB-A and USB-C connectors. The DSO510's memory will appear as an external drive, and you can copy, view, print and delete the .BMP files.
Testing the function generator
The sine wave at 1 kHz and 1.0 V
To our great astonishment, the function generator's output signal at this standard frequency and amplitude does not appear to be perfectly smooth! The oscillogram below clearly shows the staircase approximation of the pure sine wave, a characteristic of a poor low-pass filter.
The peak-to-peak value of 1.0 V is displayed by our EastTester ET3255 multimeter as 0.32267 Vrms. If you multiply that by the conversion factor of 2.828, you get 0.9125 Vpeak-to-peak, a fairly large deviation from the set 1.0 V.
So this first test does not look very promising!
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| The sine wave at 1 kHz and 1.0 V. (© 2026 Jos Verstraten) |
The sine wave at 50 kHz and 1.0 V
We repeat the measurement at the maximum frequency of 50 kHz. The shape of the sine wave is not too bad now: the staircase approximation has disappeared, but there are still some irregularities to be seen. Our ET3255 multimeter now measures a root-mean-square value of 0.31775 V, which corresponds to a peak-to-peak value of 0.8985 V.
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| The sine wave at 50 kHz and 1.0 V. (© 2026 Jos Verstraten) |
The sine wave at 20 Hz and 1.0 V
As expected, the sine wave output shows a staircase approximation at this low frequency. It is clear that there is something wrong with the low-pass filter behind the DAC! The ET3255 multimeter measures a rms value of 0.32238 V, which corresponds to a peak-to-peak value of 0.9116 V.
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The sine wave at 20 Hz and 1.0 V. (© 2026 Jos Verstraten) |
Harmonic distortion on the sine wave
Due to the still very obvious presence of the staircase approximation of the sine wave at low frequencies, measuring distortion there is of little use. We are measuring values of over 2%! As the frequency increases, the harmonic distortion decreases. At 20 kHz, our Hameg 8027 distortion meter measures a value of just 0.08%, which is certainly not bad for such an inexpensive device as the DSO510. In the oscillogram below, you can see on the blue trace what the residue on the output voltage looks like.
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Harmonic distortion at 20 kHz. (© 2026 Jos Verstraten) |
The shape of the square wave
The figure below shows the output voltage at 20 Hz, 1 kHz and 50 kHz in 'Square Wave' mode. The peak-to-peak value of the signal is again 1.0 V. There is a fairly significant deviation in the peak-to-peak value of the signal. As might be expected, the rise and fall times of the pulse are rather poor. This is clearly evident in the 50 kHz signal, where the leading and trailing edges take up approximately 20% of the total signal period.
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| The shape of the generator's square-wave voltage. (© 2026 Jos Verstraten) |
The staircase signal at 1 kHz and 50 kHz
To give you an idea of the quality of the other signals, the oscillograms below show the staircase signal at 1 kHz and 50 kHz.
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The shape of the generator's staircase voltage. (© 2026 Jos Verstraten) |
Testing the oscilloscope
Note
To make the waveforms more visible on this blog, we have inverted the images.
The bandwidth of the DSO510
The bandwidth is the frequency at which the on-screen display of a sine wave is 3 dB smaller than the display of an equally large 1 kHz sine wave. Converted to a unit of length, this corresponds to a reduction in the screen display by a factor of 0.707. If a 1 kHz sine wave is displayed with a height of 10 cm, the bandwidth is determined by the frequency of a signal of the same amplitude that appears on the oscilloscope screen with a height of only 7.07 cm.
We tested this by first measuring a 1 kHz sine wave and then increasing the signal frequency up to the specified bandwidth of 10 MHz. The amplitude of the input signal is, of course, kept constant. We monitor this on our OWON XDS2102A 100 MHz oscilloscope. The results for 1 kHz, 1 MHz and 10 MHz are summarised in the figure below. You can see that the DSO510 meets the bandwidth specification. At 10 MHz, the signal display has only dropped to approximately 0.85 of the amplitude at 1 kHz. The signal shape at 10 MHz is also excellent, and the triggering produces a stable image. Perfect, in other words!
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| Display of sine waves within the specified bandwidth. (© 2026 Jos Verstraten) |
Sine waves above 10 MHz
Above 10 MHz, the sin(x)/x interpolation used to plot the waveform on the screen begins to experience difficulties, resulting in signal distortion. It is therefore difficult to determine the exact -3 dB point. The oscillogram below shows the display of a 1 Vpp sine wave with a frequency of 15 MHz. The numerical frequency display now deviates significantly and it appears as though the oscillogram has been modulated by a low-frequency signal.
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| Display of a 15 MHz sine wave. (© 2026 Jos Verstraten) |
The display of square waves
To evaluate these, we use our Philips PM5712 high-speed pulse generator as signal source. The figure below shows the display of neat square-wave pulses with frequencies of 100 kHz, 1 MHz and 5 MHz. It is worth noting the slightly sloping 'roof' of the pulse at 100 kHz; the coupling was definitely set to 'DC'! Given the 10 MHz bandwidth, the 1 MHz pulse is still displayed clearly.
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Display of square waves at 100 kHz, 1 MHz and 5 MHz. (© 2026 Jos Verstraten) |
The rise time of the DSO510
It is noteworthy that this key characteristic of an oscilloscope is not mentioned in the specifications. The rise time is the time it takes for an oscilloscope to display 80% of the leading edge of an extremely fast pulse. For the measurement, we use a Chinese 'Fast Edge Pulse Generator' board that produces a square-wave signal of exactly 1.000 MHz with rise and fall times guaranteed to be less than 180 ps. That value is insignificant compared to the rise time of this oscilloscope. You can therefore conclude that the rise time you see on the screen is caused by the electronics in the DSO510. The circuit board is plugged directly into the oscilloscope's input. Cable parameters cannot therefore influence the signal display. The results of this test are shown in the figure below. The time base is set to the fastest setting of 50 ns/div. Measurements on the screen dump show the rise time to be 43.5 ns.
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| Measurement of the rise time of the DSO510. (© 2026 Jos Verstraten) |
Our opinion on the FNIRSI DSO510
We are satisfied with the oscilloscope. The 'AUTO' function works well and the triggering almost always produces a stable display. The ability to save waveforms is a handy extra that allows you to compare the measurements taken on your PC screen at a later, more convenient time. The actual bandwidth matches the manufacturer's specifications, something that is not often the case with such inexpensive devices.
We are less impressed with the performance of the function generator. The fact that the staircase approximation is still present in the output signal at a 1 kHz sine wave is, in fact, an unacceptable flaw in the DSO510.
A final, very personal, point of criticism is that we cannot get very enthusiastic about such combination devices. Just try, with such a combined oscilloscope/function generator, to record the amplitude/frequency response of an amplifier stage. Just give us two separate devices!
DSO510 handheld oscilloscope
