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ZOYI ZT702S/ANENG AOS02: Real User Reviews on Performance & Features?

tzok 38430 83
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Is the ZOYI ZT702S / ANENG AOS02 actually a decent low-cost hobby oscilloscope-meter, and what are its real-world performance and feature limits?

Yes: users found it good value for the money, but its usable oscilloscope performance is closer to about 5 MHz than the advertised 10 MHz, and waveforms above roughly 2 MHz start to float or jitter [#20660379][#20656825][#20656953] The multimeter side was praised for accurate voltage and resistance readings, but its bandwidth is only about 1 kHz, far below the older MT8206’s wider bandwidth [#20660379] The screen is bright and readable, the interface is responsive and intuitive, and the scope can save screenshots/waveforms [#20656825][#20660379] Early firmware had bugs such as forgetting settings after power-off and some trigger/buffer navigation issues, though later firmware updates fixed at least the saved-settings problem and were released for Zotek/Aneng units [#20656825][#20656953][#20737656][#20813843] Overall, it is seen as a surprisingly capable compact scope-meter for hobby use, but not a replacement for a real oscilloscope for higher-frequency work [#20873965][#20660379]
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  • #61 21772698
    reneeww
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    4est wrote:
    Hence also the question, as before, whether, for replacement of the original battery, to look for an 18650 LiHV cell, but without PCM, e.g. SANYO UR18650ZTA or LG ICR18650 E1, or a recycled - polaptop LG ABC28650, or a "normal" quality 18650 with a final charge voltage of 4.2 V, but with PCM? The vision of constantly overcharging the battery scares me.


    After all, you have given yourself the answer

    4est wrote:
    Somehow I feel strange if I were to rely on a BMS with a sub-standard battery.


    Since you don't want to rely on embedded circuitry in the cell then only LiHV. Also, you have an approach to this as if you had equipment for several thousand pln and not for 200.Which ever option you choose will be fine
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  • #62 21772701
    4est
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    reneeww wrote:

    After all, you gave yourself an answer

    This was a question on my part, and if it was vague, I'll put it another way: is it safe to use an 18650 cell adapted to a final voltage of 4.35 volts in this case?

    reneeww wrote:

    Since you don't want to rely on embedded circuitry in the cell then only LiHV. Also, you have an approach to this as if you had equipment for several thousand pln rather than 200. Which ever option you choose will be fine

    It's a desire to avoid a mistake that could end up in a fire, for example. Here, I guess, the prospect of the value of the equipment - a few hundred zlotys or a few thousand zlotys - doesn't really matter?
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  • #63 21772977
    tzok
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    18650 cells are generally safe, firstly, the one built in has electronic BMS protection (which itself introduces some voltage drop there), secondly, every cell of this type has mechanical protection, thirdly, the charging current in the last phase is small enough that I don't see any danger here, apart from shortening the life of this cell.
  • #64 21773014
    4est
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    After inserting an LG ABC28650 cell, sourced from a disassembled laptop battery, into the meter, the charging LED on the meter goes off when the battery reaches 4.35 volts, so as intended with the fitted circuit.
    The meter charges with a 5 V DC charger and a maximum current of 850 mA, so I hope that such a set-up guarantees peace of mind and at the same time I won't be milking the cell.
  • #65 21773228
    E8600
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    tzok wrote:
    The 18650 cells are generally safe

    I would be wary of those shipped from China in the cheapest equipment, as they vary in CID. I had a case where a cell broke like a steel pipe breaks at the seam, and the CID did not work. The cell was from a Chinese copy of a Makita battery, and had cracked while lying in a stockpile of other cells, fortunately without fireworks. My guess is that it burst out of embarrassment because it had a measured capacity of 0.5 Ah (such junk cells are in batteries added gratis to tools).
    As for the multimeter, apparently the designers envisaged putting a more modern higher capacity cell in there to make the equipment last longer, but the accountants had to save on something. I would also make sure that the multimeter does not discharge the cell below the safe threshold without the additional BMS, because maybe there is a bug on the board and the additional BMS fixed it.
  • #66 21773264
    tzok
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    I think it is rather chicano to extract a few extra minutes of operation and to compensate for the voltage drop on the BMS.
  • #67 21773536
    4est
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    E8600 wrote:

    I would still make sure that the multimeter does not discharge the cell below the safe threshold without this additional BMS because maybe there is a bug on the board and this additional BMS fixed it.

    That's an accurate point. I've put in a LiHV without a PCM to "match" the built-in charge controller, but indeed it's not clear whether the same controller will take care of the discharge level of the internal battery 🤔
  • #68 21902288
    PPK
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    ZOYI ZT-702S . Help needed. I want to upload the latest firmware. I have 1.03.55 and the drive is seen under Windows 10 but the firmware folder is empty. When trying to paste the new firmware (ZOYI-702S-FW-V58.ZTK), it appears that the memory is missing. In the "properties" of the Firmware folder there are 0 bytes and in turn the whole disk (properties) occupies 16MB. What's going on. The tutorials claim that you can format this memory to FAT32. Is there any way to copy the old version ? Or format it via USB cable. The oscilloscope version 1.03.55 menu lacks the option to format the memory.
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  • #69 21902369
    CosteC
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    PPK wrote:
    it appears that you are running out of memory.

    Don't you have lots of saved images or other data?
    Have you tried restoring factory settings on what you have?
  • #70 21902404
    PPK
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    >>21902369 In image memory zero, in firmware memory zero, if "factory" then in my "reset" menu a few times. The only thing I noticed: the waveform record (BMP file) is some bohomas (vertical lines) without sense.... After deleting the BMP files, there is ZERO in the folders but in the disk properties, it is full busy....
    p.s. After numerous hints (Google), I have no FORMAT option in the menu. The menu only has THREE subgroups, Google says there should be four.
  • #71 21902796
    tzok
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    In newer firmware, the Format option is only in the... image viewer and will help with your problem.
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  • #72 21903133
    PPK
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    >>21902796 And where is this latest wonderful firmware and image viewer. Because on their website I only found the batches.
  • #73 21903151
    tzok
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    Newer than the one described in the manual, that is, the one without the Format option in the main menu (like yours). If you go into the applications (app) you will have an image viewer and a generator and in the image viewer there will be a format option.
  • #74 21903162
    PPK
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    >>21903151 Thanks a lot but I still don't get it. Are you talking about THEIR home page ? Are you talking about version 703 ??Why an app and not some exe ? I have to configure it via smartphone-Android ? Maybe a link ?
  • #75 21903537
    reneeww
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    PPK wrote:
    >>21903151 Thanks a lot but I still don't get it. Are you talking about THEIR home page ? Are you talking about version 703 ??Why an app and not some exe ? I have to configure it via smartphone-Android ? Maybe a link ?



    He is talking about the oscilloscope. In the oscilloscope menu, look for.
  • #76 21904313
    PPK
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    In the OSCILLOSCOPE menu of my ZT-702S I have the following items (English): COUPLING; TR MODE; TRIG; PROBE;LANGUAGE; AUTO OFF; BK LIGHT; MORE MEAS; CALIBRATE; RESET; STORAGE; VERSION. And that's it.
  • #77 21904455
    tzok
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    I may have confused it with the 703, as I have both and I think it was on the 703 that I had this problem, the only solution to which was to format the internal memory from the firmware, not the computer.
    ---
    I checked on AOS02/702 and indeed, while on the 703 after the menu layout change the formatting option was moved to the screenshot viewer, on the 702 it disappeared completely, but after formatting the memory from PC level, disconnecting and reconnecting to the PC the firmware and pic folders are played and there is ~16 MB of free space.
  • #78 21905395
    PPK
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    >>21904455 Thank you. Although I have concerns because this is the LAST solution.... :) I will check.
  • #79 21905467
    tzok
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    Before writing this, I checked on my oscilloscope. It didn't "stub it out"... formatting alone will free up space, but it won't reset the file counters; these only reset after a reset to factory settings (of course it's worth doing a calibration afterwards).
  • #80 21905779
    PPK
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    >>21905467 So then, after formatting, you "manually" created folders ?
  • #81 21906424
    tzok
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    No, they created themselves when the USB was disconnected and reconnected.
  • #82 21906989
    PPK
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    OK... We check,.... with some such shyness :)
    FAT32 ?
  • #83 21907013
    tzok
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    Yes, FAT32.
  • #84 21907026
    PPK
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    >>21907013 JEEEST ! Another question. My calibration ends at -30V (graph) and at the top it displays +30V. It's as if the polarity of the display and graph (line) is swapped. There is nothing in the manual about this, just a note to disconnect the cables and not to interrupt the calibration. Is the version ZOYI-702S-FW-V58.ZTK (1.03.58) the last one for the 702 ?

    p.s. After the reset it is already OK. Range correctly displayed.
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Topic summary

✨ The ZOYI ZT702S, BSIDE ZT702S, and ANENG AOS02 are budget-friendly handheld oscilloscopes combined with multimeters, priced under PLN 300, targeting hobbyists. They feature a 10,000-count multimeter with 4 full digits, a real-time sampling oscilloscope at 48 MSa/s, 64 kB memory, and an analog bandwidth of approximately 5-6 MHz despite a nominal 10 MHz rating. The devices use an AT32F403 microcontroller with a 10-bit ADC and a well-designed analog front-end. Firmware updates have improved functionality, including remembering oscilloscope settings and fixing menu navigation issues. However, limitations remain in waveform stability above 1-2 MHz, especially for non-sinusoidal signals, likely due to acquisition algorithm constraints and lack of averaging. The x1 probe mode shows spikes and calibration challenges, but x10 mode is stable and accurate. The temperature probe included has low accuracy (~1°C resolution). Firmware updates are available from ZOTEK, the OEM manufacturer behind these brands, with shared firmware across ZOYI and ANENG models. The ZT703S is a higher-end two-channel version with a built-in generator, offering improved performance and is recommended over the ZT702S/AOS02 for users needing more features, though it costs more (~PLN 350-400). Users report some firmware bugs, limited trigger functionality at longer time bases, and navigation issues in memory buffer viewing. Overall, these devices provide good value for basic oscilloscope and multimeter functions but have inherent limitations typical of low-cost instruments.
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FAQ

TL;DR: For hobbyists under PLN 300, the ZT702S/AOS02 is a useful 48 MSa/s combo meter/scope, but users found its practical oscilloscope limit closer to 2–5 MHz. One owner called it “quite a nice piece of equipment for the money.” This FAQ helps buyers judge whether its firmware, trigger, and probe quirks matter for bench use. [#20660379]

Why it matters: This device can replace toy DSOs for basic debugging, but its real limits show up fast with small, high-frequency, or long-duration signals.

Alternative Approx. price from thread Channels / extras Thread verdict
ZOYI ZT702S / ANENG AOS02 PLN 258.97–300 1 channel, multimeter Strong value, but firmware and display limits
ZOYI ZT703S About PLN 350–400 2 channels, generator “Definitely worth paying extra”
Owon HDS242 About PLN 470 2 channels Better on paper, but higher cost

Key insight: The thread’s consensus is simple: the ZT702S/AOS02 is good enough to keep on a hobby bench, but not good enough to trust near its headline oscilloscope specs. Firmware updates improved behavior, yet users still report trigger, x1 probe, storage, and high-frequency display issues. [#21141649]

Quick Facts

  • The most repeated real-world oscilloscope limit was not 10 MHz. Users said waveforms are comfortably usable to about 2 MHz and still recognizable up to roughly 5 MHz. [#20660379]
  • The multimeter side impressed more than the oscilloscope side. One owner checked voltage and resistance against standards and reported about ±1 least significant digit on voltage, with resistance also “on point.” [#20660379]
  • Practical scope ranges reported in use: minimum sensitivity 200 mV/div with a x10 probe, maximum 100 V/div, and time base from 100 ns/div to 20 s/div, with roll mode from 250 ms/div. [#20660379]
  • Firmware mattered early. Version 1.03.51 was seen in July 2023, and version 1.03.58 later fixed the confusing ammeter menu layout and remained installable on ANENG-branded units. [#20813843]

How well does the ZOYI ZT702S / ANENG AOS02 actually perform as a budget oscilloscope and multimeter in real-world hobby use?

It performs well as a cheap bench companion, but better as a multimeter than as a serious oscilloscope. Users praised the bright screen, fast refresh, screenshots, and roughly ±1 least significant digit voltage accuracy, while also reporting that scope work becomes less trustworthy above about 2–5 MHz. One buyer paid PLN 258.97 for an ANENG AOS02 bundle and judged it a useful replacement for toy DSOs. If you mainly debug low-frequency logic, power, or audio, it fits the job. [#20660379]

Why do waveforms on the ZT702S/AOS02 start to float, shake, or look distorted above about 2–5 MHz even though the spec mentions 10 MHz bandwidth?

They float because the hardware and acquisition method run out of margin before the headline spec. Multiple users said 48 MSa/s real-time sampling makes 10 MHz “fiction,” and one tester saw non-sinusoidal signals become unstable above 1 MHz, with sine waves degrading above 5–6 MHz. Another owner said the trace starts to “float” above 2 MHz, even though the shape remains recognizable up to about 5 MHz. In practice, the display looks less like distortion measurement and more like rough waveform indication. [#20660379]

What limitations should I expect from the ZT702S oscilloscope input sensitivity, time base, and trigger behavior when measuring small or fast signals?

Expect clear limits with weak, fast, and offset-sensitive signals. One owner reported a minimum of 200 mV/div with a x10 probe, a maximum of 100 V/div, and a time base of 100 ns/div to 20 s/div. That user concluded the scope is comfortable up to about 2 MHz and about 1 V amplitude. Trigger level also showed about a -3% offset after calibration, so a displayed 0 V trigger could behave like about -300 mV at 1 V/div sensitivity. Small signals are where the compromise shows first. [#20660379]

How do you update firmware on the ANENG AOS02 or ZOYI ZT702S, and where can the official firmware files be downloaded?

You update it through the device’s USB storage, not with a PC installer. 1. Connect the meter to a computer and open its internal drive. 2. Copy the firmware file into the firmware area. 3. Disconnect so the device can process the update. Users said ANENG-branded units can use the same ZOYI/ZOTEK firmware, and one post linked official downloads at the ZOTEK firmware update page when v1.03.58 was released. [#20813843]

Why does the x1 probe mode on the ZOYI ZT702S / ANENG AOS02 show spikes or strange amplitude behavior compared with x10 mode?

x1 mode behaves worse because it is not compensated like x10 mode. One owner said this is a general rule and that they never use x1 on a normal oscilloscope. Another user saw strong spikes in 1:1 mode during calibration, while x10 looked clean. Later testing also showed setup matters: after recalibration, another owner found the x1/x10 menu setting worked correctly again, with the calibration square wave reading about 3.27 Vpp in x1 and 3.08 Vpp in x10. [#20835929]

What is real-time sampling (RTS) in an oscilloscope, and how does it affect what the ZT702S can display accurately?

"RTS" is an oscilloscope sampling mode that captures each waveform from live, single-pass samples, without reconstructing it from repeated cycles, which makes sample rate the hard limit for accurate high-frequency display. On the ZT702S, users explicitly tied its behavior to 48 MSa/s RTS and said you should not expect faithful reproduction much above 5 MHz. That explains why the device can still show a trace near 10 MHz while no longer showing a trustworthy shape. [#20656831]

What is a LiHV 18650 cell, and why are some users worried about the ZT703S charging circuit taking the battery up to 4.35 V?

"LiHV 18650" is a lithium-ion cylindrical cell that charges to a higher final voltage, typically 4.35 V instead of 4.20 V, which increases runtime but requires a charger designed for that upper limit. Users opened the ZT703S and identified an ME4086B charger IC, then noted it charges the internal cell to 4.35 V. The concern is simple: replacing the original cell with a standard 4.20 V 18650 could overcharge it, even if the current tapers late in the cycle. [#21772625]

How accurate is the multimeter side of the ZT702S/AOS02 for voltage, resistance, temperature, and AC measurements compared with its oscilloscope mode?

The multimeter side is the stronger half of the product. One owner checked DC voltage against a standard and reported about ±1 count error, with resistance also matching reference resistors closely. AC measurement bandwidth was described as a typical 1 kHz, which is modest. Temperature measurement with the included probe was criticized for only 1°C resolution, but another user replied that 1°C is realistic for a K-type probe in this class. Overall, the meter inspires more confidence than the scope. [#20660379]

What causes the ZT702S/AOS02 NORMAL trigger to miss long pulses at slower time bases like 100 ms/div or 1 s/div, and what workarounds help?

Users traced the missed pulses to firmware behavior in NORMAL trigger mode at slow bases, not to a broken input. One tester using 50–300 ms pulses said NORMAL worked properly at 50 ms/div and below, but at 100 ms/div it started dropping pulses and could trigger on every other pulse. The same post also described awkward buffer navigation after capture. A workable approach is to capture, stop, reduce the base, and inspect the buffer with MOVE, though the memory map still stays confusing. [#20737656]

When the ZT702S internal USB storage looks full even though the firmware and picture folders are empty, how do you recover space and restore the folders?

You recover it by formatting the device’s internal storage as FAT32 from the PC side, then reconnecting it. A user with firmware 1.03.55 reported 0-byte firmware and picture folders while the whole 16 MB drive still looked full. Another owner tested the fix directly on an AOS02/702 and said the firmware and pic folders recreate themselves after USB disconnect and reconnect. A factory reset afterward can also reset file counters, and recalibration is recommended. [#21904455]

Which firmware issues were fixed in later ZT702S/AOS02 releases like v1.03.58, and what bugs still remain according to users?

Later firmware fixed some usability issues, but not the core oscilloscope compromises. Users reported that updates added scope-setting memory retention and that v1.03.58 corrected the confusing ammeter option layout. At the same time, owners still reported high-frequency waveform instability, odd x1 behavior before recalibration, storage quirks, occasional screen-refresh glitches after saving images, and missed long pulses in NORMAL trigger mode. By May 2024, one poster felt development had slowed and bug fixing had largely stopped for the 702 series. [#21085557]

How does the ZOYI ZT703S compare with the ZT702S and the Owon HDS242 for price, usability, channels, and overall value?

The ZT703S is the better instrument if you can spend more. In the thread, owners placed the ZT703S around PLN 350–400, versus about PLN 258.97–300 for the ZT702S/AOS02 and about PLN 470 for the Owon HDS242. Users said the 703 is “definitely worth paying extra” because it adds two channels and a generator, while one poster still preferred ZOTEK’s interface over Owon’s. Another user argued the HDS242 is the smarter step-up if you can stretch the budget. [#21141649]

What frequency ranges and output amplitudes does the built-in generator on the ZT703S support for sine, square, triangle, sawtooth, and related waveforms?

On firmware batch 1.3.9, users measured broad generator ranges in application mode and much smaller ones in Output mode. Application mode ranges reported were: sine 50 Hz–344 kHz, square 50 Hz–500 kHz, triangle 50 Hz–100 kHz, half-sine 50 Hz–129 kHz, double half-sine 50 Hz–294 kHz, and sawtooth 50 Hz–100 kHz. Output mode, which shows the waveform on-screen, was limited to 10 Hz–5 kHz for sine, square, and triangle. Peak-to-peak output was usually 2.5 Vpp, but sine fell to 2.0 Vpp above 995 Hz. [#21220569]

How does cyclic measurement work on these ZOYI/ANENG meters, what time interval can be set between measurements, and where are the logged results stored or graphed?

The thread does not provide a usable answer, because nobody documented the feature with settings, intervals, or storage behavior. One user asked whether cyclic measurements save results, allow interval selection, or draw a graph, but the reply only explained cyclic signal measurement in general and did not test the meter’s logging functions. So from this thread alone, there is no verified time interval, no confirmed memory logging method, and no confirmed results graph. [#20875742]

What is BMS or PCM protection in an 18650 battery, and how does it matter when replacing the original cell inside a ZT703S?

"BMS or PCM protection" is a small battery protection circuit that monitors a lithium cell for unsafe charging, discharge, or current conditions, adding a safety layer but also some voltage drop and packaging complexity. In the ZT703S discussion, users said the factory cell includes integrated protection, while replacement choices raised two risks: charging a 4.20 V cell up to 4.35 V, and not knowing whether the meter itself prevents over-discharge without that extra board. That makes protection type part of the battery decision, not just capacity. [#21773536]
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