ANENG PN129 is an open jaw clamp meter (sometimes called an open fork meter or clamp-on tester) is a handheld electrical testing tool used to measure current in a conductor without breaking the circuit. Unlike traditional clamp meters that have a hinged jaw you open and close around a wire, an open jaw clamp meter has a fixed U-shaped or fork-shaped opening. You simply slide the conductor into the open fork, and the meter uses a magnetic field sensor to measure the current flowing through it. This is useful for quick current checks without disturbing wiring. U-shaped clamp design (≈12 mm opening) that allows easy, non-contact measurement of current on single conductors.

Measurement Capabilities of ANENG PN129

AC/DC Current: Up to 100 A
AC/DC Voltage: Up to 600 V
Resistance: Up to 20 MΩ

This meter can make true RMS (TRMS) measurements with 4000 counts for added precision. ´

In addition to numeric measurements, this meter has continuity Test (with buzzer), NCV (non-contact voltage detection), data hold, auto power-off (approx. 15 mins), backlit LCD, and even a built-in flashlight for dim environments.

ANENG PN129 is compact size (160 × 37 × 26 mm) and lightweight (~68 g). The meter is safety rated CAT III 600 V for safe electrical use in wide variety of electrical circuits. Rated CAT III 600 means that it is suitable for many household and light industrial applications.

Supplied accessories (normal version): includes test leads, multiple adapters (alligator clips, probes), batteries, and a storage bag.

Videos:

ANENG PN130 Clamp Meter,4000 Counts,Auto Range,NCV Non-Contact Voltage Detection

ANENG PN129 Digital Clamp Meter 600V 100A Multimeter with LCD Backlit Display Review

ANENG PN129 U-Type Current Clamp Meter,Automatic Range 4000 Counts,Measure Automotive DC Current

ANENG PN129 Digital Clamp Meter 600V 100A Multimeter with LCD Backlit Display Review

ANENG PN129 Digital Clamp Meter 600V 100A Multimeter with LCD Backlit Display Review

ANENG PN129 U-Type Current Clamp Meter,Automatic Range 4000 Counts,Measure Automotive DC Current

Measurement features:

For AC current measurement, no need to break the line, non-contact measurement AC current. Just power on the meter from power button it enters to AUTO mode, where it can measure AC current, DC voltage, AC voltage, DC voltage and resistance (with beeper for low resistance).

For DC current measurement press “A–NCV” once to enter DC current. In this mode you need to often use ZERO button to calibrate out the outside magnetic fields effect from the measurement.

When you press “A–NCV” second time, the meter goes to AC current measurement mode.

NCV induction detection, press “A–NCV” once more to enter NCV and it is detected. The display will show you EF and NCV. When there is considerable AC voltage near the tip of the u-shaped jaw tips an alarm will sound and display will show ——-.

On the side of the meter there is a Hold/lamp button. A short press will enable and disable data hold. When you press a little longer, the built in LED flashlight and the display back light.

When measuring the current (AC or DC), you need to have the wire close to the innermost end of the u-shaped jaw to get the best accuracy. The U-shaped open-jaw measurement works well for AC with quite good accuracy as long as you can get the wire to the right position (deep enough).

For DC measurement you need to note that there could be error in the result because of external magnetic fields can affect the current measurement. Turning the meter to different directions can easily cause readings up to few hundred mA without any wire nearby. To do reliable DC measurement, you should move the the meter to near the measuring location, then press ZERO and then move the meter (without turning it) to the measurement position. This external magnetic field affecting to measurement is typical (more or less) to all DC capable non contact meter, those U-shaped open jaw meter being considerably more sensitive to external magnetic fields that clamp meters (that are less sensitive). Please also note that magnetic tools placed near the U-shaped measurement location can cause measurement error. That’s typical to this type of instruments, and not a flaw in the PN129.

What is inside meter:

ANENG PN129 PN130 DC CURRENT U CLAMP METER
This video has teardown of model PN130 meter (version with rechargeable battery) starting at around 12:00

The ANENG PN129 is a budget-friendly multimeter that is relatively well-built for its price range. The PN129 has a straightforward design, with no components on the back of the PCB and no through-hole components. The component count is minimal, reflecting its low cost and intended basic functionality. Given its lack of moving parts and relatively robust build, it should be reasonably durable for general use in a toolbox.

The measurement principle for current measurement is that when electricity flows through a conductor, it creates a magnetic field around it. Inside the jaws, there’s a sensor (possibly Hall effect sensor) that detects this magnetic field. The sensor converts the magnetic field strength into a voltage signal, which is then processed by the meter’s circuitry to display the current value.

Pros:

Handy U-clamp design for fast, non-invasive current checks.
Wide measurement ranges (up to 100 A and 600 V).
Convenient extras: NCV, flashlight, auto features, data hold.
The ANENG PN129 is a budget-friendly multimeter, and while it may not be a precision instrument, it’s generally considered a decent value for its price.
Continuity and voltage measurement works well.

Considerations:

As a budget-friendly multifunction device, it may not match standalone tools in professional-grade accuracy or ruggedness or measurement features.
The fork-style current “clamp” is not as accurate as a closing-style clamp: Current measurement is sensitive to wire position inside U clamp, so does not always feel reliable (especially in DC measurement). If you need very good accuracy, consider buying a closing clamp meter instead.

Result:

Not bad for the price point. This meter costs around 30 Euros in Amazon and price 10-20 Euros in AliExpress, Temu, Banggood.

The ANENG B16 Induction (Tester) Pen—a compact is pen-shaped NCV (non-contact voltage) tester with some features of a multimeter.

Key Features & Specs:

• NCV AC Voltage Detection (Non-Contact): Detects AC voltage between 12 V and 300 V, suitable for everyday wiring, sockets, light fixtures, and low-voltage circuits. By simply bringing the pen close to a wire, users can identify voltage without direct contact. Equipped with both sound and light alarm features, the tester pen alerts you immediately upon detecting voltage
• Contact AC voltage measurement: By bringing the in contact with a wire energized metal parts, users can measure the voltage on the wire.
• Live/Neutral Wire Identification: Helps you distinguish between the live (hot) and neutral wires.
• Breakpoint/Continuity Tracing: Useful to trace a cable and locate where a wire is broken—indicator fades at the break point.
• Works in dark: LCD with Backlight provides clear readout of detected voltage and remains visible in dim lighting. Built-In Flashlight is handy for illuminating dark junction boxes or cramped spaces.
• Sound & Light Alarm: Alerts you via both buzzer sound and visual cues when voltage is detected.
• Slotted Screwdriver Tip: The steel pointed tip doubles as a flathead driver—combine testing and minor adjustments in one tool. It can be used screw in and repair electrical appliances in task that do not need a lot of force.
• Auto Power-Off: Powers down after roughly 3 minutes of inactivity to conserve battery.
• Safety: CE CAT II 1000V / CAT IV 600V according to documentation that come with the instrument.
• Dimensions: ANENG B16 is built ABS plastic body with total length of around 166 mm and maximum diameter of around 28 mm.
• Weight: The instrument wights around 60g total when batteries are installed to it. There is a pen clip on the back of the ANENG B16 Voltmeter tester.
• Power Source: Runs on two AAA batteries

AC Voltage Range: NCV Non-contact 20~1000V and contact 0~300V
Frequency 50/60Hz
Alarm Method Sound and Light Alarm
Flashlight White LED Lighting Fixture
Use Battery 1.5V AAA battery X2
Product Size 160×28.5×26.3mm
Product Weight 60g with batteries installed

Package Included:
1 x ANENG B16 Digital Tester Pen
1 x User Manual
1 x Packing Box

The ANENG B16 is a compact, budget-friendly tester pen ideal for quick checks to ensure a wire or socket is live. Its LCD, flashlight, and built-in screwdriver make it versatile for light-duty tasks.

The Aneng B16 is advertised as an intelligent induction test pen, not a traditional multimeter. It primarily measures AC voltage, identifying live and neutral lines, and can locate circuit breakpoints. It also features Non-Contact Voltage (NCV) detection for identifying live objects and a flashlight.

The B16 is best for quick, on-the-fly checks—like verifying that a circuit is live. The non-contact induction detection system that ensures no direct contact with live wires is necessary. You can also it to use to measure the mains voltage on wires, which can be useful compared to simpler non contact testers, but don’t rely on it for precision readings. In best cases it gives quite accurate results, but there are many things that can cause measurement errors.

Non-contact 12-300V AC measurement is somewhat misleading description. To measure voltages, I would not say B16 is true contactless instruments. To get voltage readings, the tip of the B16 needs to touch the voltage being measured and user needs to touch reference on the instrument. The user needs to ensure that during use your fingers maintain full contact with the touch reference point on the pen to maintain decent accuracy. The manual recommends to avoid contact with other metal or being near strong electric fields as this may skew results.

Digital Measurement of Voltage:
1. After booting up, select the number mode with the selection key, and the screen will display “0V”
2. Touch the touch pole with your fingers and use a probe to contact the AC charged body
3. Display the value of contact voltage on the screen (0-300V)

When using it, you need to keep in mind its limitations—it’s not a precision instrument and should be a preliminary tool rather than the only test used for important electrical work.

I was first a little bit worried on the safety, because you needs to touch the live circuit with the meter tip and touch the metal reference point on the meter that the same time. It can be a little bit frightening to trust just some cheap chinese electronics between potentially lethal voltage and your finger. The meter advertises CE CAT II 1000V CAT IV 600V ratings, which should mean safe enough for electrical working. I also took a look inside to be sure, and the construction looks OK. More on that later.

The meter is available from Temu, Banggood and AliExpress.

The meter is designed to measure AC voltage range 12V~300V. Select the voltage measurement mode,the screen displays ~V,touch the touch pole of the electric pen with your hand,and insert the electric pen into the socket for identification. The voltage measurement mode can be used to detect the live and neutral on the mains outlet. Touching the live wire should show around the mains voltage and touching the neutral side is expected to show zero volts or low voltage reading.

The LCD screen comes with a backlight when it is turned on, and the values on the screen can be clearly seen in a dark environment, and the readings are easy. The meter has also a built-in LED lamp that shines to the direction the meter tip points to. The screen is well-lit, making it easy to read even in low-light conditions. Additionally, the audible alarm alerts you to the presence of voltage.

ANENG B16 intelligent induction test pen AC voltage range 12V~300V,measuring circuit breakpoints

ANENG B16 Digital Tester Pen 12V-300V Non-Contact Voltage Detection LCD Display Sound Review

Attention: During the testing process, the fingers must be in full contact with the touch pole piece. The AC voltage measurement must be in contact with a live conductor in order to obtain accurate values. If it comes into contact with metal objects or the outer skin of charged conductors covered by an electric field, or if it is non-contact in a super strong electric field, although the voltage value will also be displayed, this value is for reference only and cannot be used as an accurate measurement basis.

Here is a look inside:

In this last picture you can see several high resistance high voltage resistors from the measurement tip to the measurement circuit input. The ground side of the electronics is directly connected to the touchable reference point on the side of the B16. The insulation distances on the circuit seem to be good where they are needed.

I did a measurement of the input resistance and insulation with an insulation resistance meter. I got reading of around 176 megaohms with 500V DC measurement voltage.

The ANENG B16 Digital Tester Pen was advertised as an impressive tool that seamlessly combines functionality with user-friendliness. Designed for voltage detection, it operates within a range of 12V to 300V, making it suitable for a variety of household and professional electrical tasks.

At the best is is a very handy tool. Being at same price range as many simpler non-contact voltage testers, it offers excellent value for money because of more features built in.

There are also downsides. The construction feels somewhat cheap and not high quality. The voltage measurement has limitation that it easily can measure very inaccurately. AC Voltage measurements are not accurate, but it’s not a meter. For quick checking it’s often enough.

The internal resistance is measured by ohm (Ω). The value of internal resistance varies depending on multiple factors, such as battery size, cathode electrode, anode electrode, separator, electrolyte, temperature, and state of charge (SOC) of the battery. Internal resistance is one of the parameters that indicate a battery’s ability to carry current.

When the value of internal resistance is low, the battery is able to carry a significant amount of current. On the other hand, a battery with high internal resistance can only carry a small amount of current. One reason for measuring internal resistance is for battery maintenance: The internal resistance of a battery gradually increases as it is used. By measuring the internal resistance of the battery on a regular basis, a degraded battery can be eliminated before it becomes a problem.

To measure the battery internal resistance, a special instrument designed for this is the the best option to use. I ordered some time ago RC3563 Lithium Battery Internal Resistance Tester with 4-wire Probes to be able to measure battery internal resistance (and other low resistances).

The RC3563 battery internal resistance tester can measure internal resistance and voltage of the battery at the same time. It is very nice to get the measurement results of both resistance and voltage at the same time. RC3563 can accurately test internal resistance of your batteries with voltage range of 0-100v. RC3563 can also measure low resistance resistor values.

The measurement with RC3563 battery internal resistance tester is done using the Kelvin four-wire test clamp. Kelvin four-wire method avoids the influence of contact resistance and wire resistance (when used correctly), so accurate measurement can be performed.

Specifications:
Speed: 5 times/second
Adjustment: Correction for resistance and voltage separately
Basic accuracy:
Resistance: 0.5%
Voltage: 0.5%
Measuring ranges:
Resistance: 0.0001mΩ~200Ω
Voltage: 0.0001V~±100V direct current
Resistance ranges: 6 ranges automatic and manual
Voltage ranges: 3 ranges automatic and manual
Battery: 1 * lithium battery, 1000mAh (included)
Package size: 180 * 90 * 35mm / 7.1 * 3.5 * 1.4in
Package weight: 250g / 8.8ounce

This tester adopts intelligent control and large display, also with built-in 1000mAh lithium battery.

According to manufacturers the instrument can measure any type of batteries, including lithium batteries, lead-acid batteries, nickel-chromium batteries, dry batteries and so on. You can measure batteries of any capacity, no matter how big it is, as long as the internal resistance is within 0-200 milliohms and the voltage is within 100V. The battery’s full and depleted state will not affect the battery’s internal resistance, and can be measured, with minimal changes in internal resistance (except for defective batteries).

When I ordered the meter, I ordered few different test clamps suitable for different uses.

The RC3563 battery internal resistance tester uses AC resistance measurement method. So the tester gives Alternating Current Internal Resistance, commonly called AC Impedance or Impedance
. This tester seems to give quite accurate reading of battery internal resistance. The measurement works correctly even without battery voltage present, so RC3563 can also be used to measure the AC resistance of low-ohms resistors. Because the AC measurement method (around 1 kHz signal), this meter cannot be used to measure RC resistance of inductive components like coils, transformers or electric motors.

From: https://github.com/ludwich66/RC3563/wiki
Measurement AC Resistance DC Voltage
Accuracy Resistance 0,5% Voltage 0,5%
Range 1 µΩ – 200 Ω 1 mV – 100 V DC
Ranges 6 3
Current 2 mΩ @ 50mA
Current 20 mΩ @ 50mA
Current 200 mΩ @ 5mA
Current 2 Ω @ 5mA
Current 20 Ω @ 0,5 mA
Current 200 Ω @ 0,5 mA

Test signal frequency: AC 1 kHz

Here are some videos of RC3563:
Battery tester RC3563

High Precision Li Ion Battery Internal Resistance Tester RC3563 Close view

RC3563 battery tester – Excel and automatic measurements / PC communication (18650) video presents a way to connect the RC3563 meter to a computer and semi-automatic data reading using an excel sheet.

When I received the meter, I had some problems with the measurements. The situation was somewhat similar to RC3563 Battery Tester (inconsistent readings?) video that shows inconsistent Internal Resistance readings from meter. I originally had a similar problems that the internal resistance and voltage results were inconsistent.

I opened the meter and did some investigation.

After some investigation I found out that there were some bad soldering joints inside the meter with the two big electrolytic capacitors in the measurement circuit. After re-soldering the problem was solved.

If the meter itself is OK, but test result are unstable, it may be that the test clip is in poor contact with the battery, or the battery under test is unstable, the electrode has an oxide layer, or there is a strong magnetic field around it.

Instructions for use:
1. Short press “enter key ” to turn on.
2. Long press “enter key ” to shut down.
3. Press the “set key” to enter the setting state, then press the “select key” to select different functions, and then press the “enter key” to enter the corresponding function.
4. Enter the resistance calibration/voltage calibration state. At this time, the test line should clamp the calibration resistance or voltage, press the “set key” to select the gear to be calibrated, and then press “+” and “-” to adjust the displayed value to be equal to the calibration resistance or voltage , Press the “select key” to select “ok” or “Cancel”, and finally press the “enter key ” to decide whether to save or cancel.

Documentation links:
https://github.com/ludwich66/RC3563/blob/main/RC3563_Manual_English.pdf
https://www.scribd.com/document/660147456/RC3563-Manual-English
RC3563 RC3562A Resistance-Checker, Battery Tester, Milliohm Meter, Software, Manual

How does the battery internal resistance show in the circuit? The following picture from Hioki learning material shows an example of the internal configuration of a battery. Ideally, a battery’s internal resistance should be zero, allowing for maximum current flow without any energy loss. In reality, however, some internal resistance is always present.

Can the internal resistance be measured to judge whether the battery is good or bad? The answer is usually yes. The same battery will gradually wear out during use, the capacity becomes smaller and smaller, and the internal resistance becomes larger and larger.

When making battery measurements, it is good to know what are the the right internal resistance values to expect.

The typical internal resistance for new high-capacity NiMH rechargeable AA batteries is between 30mΩ and 100mΩ, and for an alkaline battery it is usually between 200mΩ and 300mΩ (but as high as 700mΩ, depending on its charge status). Faulty rechargeable batteries have a much higher internal resistance.

The internal resistance of the new 18650 lithium battery is generally below 50 milliohms, the better is about 20 milliohms, the general is about 30 milliohms. Here is a table for 18650 from https://www.xtar.cc/news/10-things-to-know-about-lithiuim-ion-battery-internal-resistance-224.html with somewhat different numbers:

What is the impedance of a 12V battery? The battery internal resistance values varies depending on the battery size. Lead-acid batteries typically have a low impedance, therefore the ability to deliver high currents. Typical impedance for a battery in the standby industry is 12V 80Ah VRLA battery that has typically around 0.003 Ω (3.0mΩ). The short circuit current is typically specified on battery datasheets, e.g., 2,500A for 12V 80 Ah battery. Those values can be used to get idea of the internal resistance (12/2500 = 0.0048 ohms).

A brand new, fully charged 12V lead acid battery typically has an internal resistance around 10-20 milliohms or less. If IR is between 5 to 10 milliohm, it is in good condition. If IR is less than 5 milliohm, it is in very good condition. If IR is between 10 to 30 milliohm, still poor condition but may be usable or revivable. A battery with an internal resistance above 50-60 milliohms is likely nearing the end of its useful life. 12V batteries with IR over 100 milliohms, are likely sulfated, damaged, or otherwise in poor condition and should be replaced.

Typical impedance for a battery in the standby industry:
12V 80Ah VRLA battery = 0.003 Ω (3.0mΩ)
2V 800Ah VRLA battery = 0.0002 Ω (0.2mΩ)

Table with more values from https://xtester.cn/product/RC3563_battery_Internal_resistance_tester.html

When measuring large-capacity batteries (the internal resistance is very small), you must pay attention to the position of the clip during the measurement. The internal resistance of the battery electrode or connecting wire is often greater than the internal resistance of the battery itself. Pay attention to the position of the clip and make good contact. To get an idea of the size of impedance, let’s compare the typical battery impedances to the resistance of the wire in a standard IEC power lead. The wire length equivalents of the impedances mentioned are 330mm (13.0 inches) and 22mm (0.87inches).

Product links:
https://xtester.cn/product/RC3563_battery_Internal_resistance_tester.html
https://www.amazon.com/LeTkingok-Precision-Handheld-Internal-Resistance/dp/B09HBYBWT8
https://www.aliexpress.com/item/32975204607.html
https://www.aliexpress.com/item/1005005930826266.html
https://www.aliexpress.com/item/1005005574356839.html
https://www.aliexpress.com/item/1005005538739198.html
https://www.aliexpress.com/item/1005005461280358.html
https://hklrf.com/RC3563-Battery-Internal-Resistance-Tester-100V-3Digit-Lead-Acid-Lithium-Battery-Tester-True-4Wire-Auto-Battery-Detector_1885.html

The tester has an USB interface to computer (looks like USB serial port with default baud rate 115200). Here are links to software to get measurement results to computer:
https://github.com/ludwich66/RC3563
https://secondlifestorage.com/index.php?threads/rc3563-ir-tester.8380/page-2#post-79687

The RC3563 is not the only battery resistance tester in the market. Another quite similar is YR1035+/YR1030+ Lithium Battery Internal Resistance Test Instrument that was reviewed in another site.

High frequency strobing can be hard to detect with your eyes. This issue relates to the fact we have a 50Hz electricity supply. In this system, electrical current alternates or cycles 50 times per second. Well designed LED lights effectively ‘smooth out’ this constant back and forth of the current flow. Cheap and nasty LEDs cycle on and off completely, 50 or 100 times per second. In countries with 60 Hz power, the flicker can be at 60 or 120 times a second. We know this is bad because old-style fluorescent tubes can suffer from the same problem. High frequency flicker in offices has been linked to increased headaches and visual discomfort.

If you want a flicker free LED bulb, how to find it? The markings on the packet usually don’t tell about how much this specific LED bulb flickers or not. So you need to test yourself. Your phone camera can potentially provide some insight into LED bulb flickering (the pulsing screen is an indicator of this flicker): At hardware stores they have a row of sample bulbs that are on, put your phone camera up to them to see how much flicker. Then buy the best ones.

IKEA LED lamps flickering comparison

The majority of people have seen flickering light bulbs. LED lights, despite their incredible efficiency and supposedly infinite longevity, do flicker on occasion, just like any other lighting system. If you have flickering LED bulbs, that flicker either all the time or when mains voltage varies, homeowners may have to troubleshoot and fix the issue to ensure maximum comfort and functionality of their lighting system.

When using LED lamps, certain appliances may not function properly. LED bulbs have commonly issues when using lighting switches that also incorporate a dimmer controller. Most LED lights are not compatible with traditional dimmer switches, causing flickering in some instances. If you have dimmer switches, start by purchasing products that have market-proven wide compatibility. Just because other lights have flickered, it does not mean that all LEDs will flicker with your dimmer.

The light fixtures in your home will eventually also get old, broken, and rusted. This can nonetheless result in flickering light bulbs. The simplest way to avoid the dangers of flickering LED lights is to ensure that your LED lights are properly fitted (twist the LED bulb to make sure it’s not just a loose). The next test for flickering LED bubs, remove the flickering bulb and replace it with a working one. If the flickering persists, it could be your light fixture. If the flickering persists after you change the fixture, have a professional inspect the wiring. If there is something wrong with the power source, you should call an electrician to have it serviced.

Low-cost LED bulbs may result in flickering, so it’s beneficial to use high-quality ones. High-quality LED bulbs often come with features, that can help prevent flickering and ensure optimal operation. But claimed high quality, well known brand name or high price does not guarantee good results.

If you see any brief flickering, consider if anything else is going on in your home. When huge appliances are turned on, lights may briefly flicker. Led lights mainly flicker either because of voltage changes or a loose wiring connection. Voltage change can happen when turning on a large appliance. Light flicker caused by starting intense appliances like a corded vacuum cleaner or other tools is usually not a cause for concern. Because they suck a lot of power, they can cause a voltage reduction. If your LED lights hook up to the same circuit as the appliances, they may flicker or dim.

Energy utilities control off-peak loads by sending a ‘ripple’ through the electricity grid. Often, this electrical signal can show up in the form of flickering lights or noisy fans. Other disturbances on the grid can be due to nearby electrical loads (like neighbour cranks up their welder or high power grinder).

Products in the pictures:
USB-kaapeli tyypin C liittimellä
USB-kaapeli tyypin C liittimellä

I finally bought one: UT60BT. This UT60BT multimeter is feels reliable and feature-packed tool. This meter connects to your smartphone via Bluetooth, allowing you to remotely view and log measurements. This CE-certified meter meets CAT II 1000V/CAT III 600V safety rating with rugged double-injection housing. One of the standout features of the UT60BT is its Bluetooth functionality, which allows users to connect the multimeter to their smartphones or tablets via the UNI-T’s dedicated app.

UT69BT multimeter belongs to UNI-T UT60 series of multimeters. Those BT60 series multimeters are auto-ranged meters that can measure up to 1000V AC/DC voltage, 10A AC/DC current and 100MΩ resistance.

UT60BT digital multimeter provides True-RMS measurement, 9999-count resolution, non-contact voltage detection, resistance measurement, capacitance measurement, diode test, temperature measurement and frequency meter. The meter uses a quite fast ADC that gives good measurement speed (3 times/s) in most ranges. The voltages and currents measurement offer automatic and manual range selection.

UT60BT multimeter comes equipped with essential safety features, such as overload protection and a built-in fuse, ensuring user safety and device protection during operation. It has 1000V rms overload protection on all ranges, the current range is protected by a 10A / 1000V, 6.35 x 32mm tubular fuse. The meter is safety certified by an independent test lab verification (tested by Intertek).

The meter has easy-to-use interface with a backlight enables you to detect equipment quickly even in dark places. The selector switch feels mechanically well built and the meter makes a short “beep” sound when you turn the selector. This digital multimeter tester also has a data hold function. There is also acousto-optic indication (beep and LED indicator) for NCV (non contact voltage) and continuity (30 ohms) ranges.

This meter is marketed as a smart multimeter: It can connects to your smartphone via Bluetooth. This connection allows to remotely view and log measurements. No need for writing down readings or manual calculations. The measurement results are available to smart phone with UNI-T Smart Meter app for Android phones. The application can show the numeric value and can also show graphical view of result and can also control the multimeter operation (you can do same things than with the push buttons). The Bluetooth connection is activated by pressing the yellow button in multimeter, after which the UNI-T app will detect the multimeter.

In terms of performance, the UT60BT offers impressive accuracy in various measurement functions, including voltage, current, resistance, capacitance and frequency. I did some tests that showed that this meter is pretty accurate. According to my testing the DC voltage, AC voltage, DC current, resistance, capacitance and frequency measurement ranges operated all more accurately than the manufacturer technical specifications promised. In for example in voltage, resistance and capacitance ranges I was positively surprised how accurate the meter was (I measured my references and compared to my accurate 4 1/2 number accurate “reference” multimeter that was tested against calibrator few years ago).

UNI-T UT60BT/EU CHEAP-O Multimeter Review & Teardown
https://www.youtube.com/watch?v=dc6Hx8mU5_0

Some more review videos:

UNI-T UT60BT/EU CHEAP-O Multimeter Review & Teardown
https://youtu.be/dc6Hx8mU5_0?si=4MKYteWciLCxqwte

UNI-T UT60BT 9999COUNTS BLUETOOTH MULTIMETER CATII 1000V,CATIII 600V
https://youtu.be/cZT9yFeTcZk?si=mGIO9bt-9jNpwvYb

UNI-T UT60BT BLUETOOTH MULTIMETER.
https://www.youtube.com/watch?v=oFuViNd85NY

UNI-T UT60BT 9999COUNTS BLUETOOTH MULTIMETER CATII 1000V,CATIII 600V
https://www.youtube.com/watch?v=cZT9yFeTcZk
- includes teardown

UNI-T UT60BT/EU CHEAP-O Multimeter Review & Teardown
https://www.youtube.com/watch?v=dc6Hx8mU5_0

The recommended application to get the measurement results from the UT60BT is the UNI-T Android app. But there is potentially other third party software: The Python based PC software available at https://github.com/ljakob/unit_ut61eplus tells is is designed to access digtal multimeter UNI-T UT61E+ from Python via CP2110 based USB connection but should work also for UT60BT.

In conclusion, the UT60BT multimeter from UNI-T is a reliable and feature-packed tool that delivers accurate measurements, convenient data logging capabilities, and robust build quality. Very good meters for the price (around 40 Euros). For safety UNI-T is a reputable enough brand that their CAT safety ratings are the real deal (and here they are verified by known test laboratory). The supplied measurement probes are OK.

Some ideas that would be been nice if they would have been available on the meter: analog bar in display (like in UT60S), official PC software would have been nice and loZ measurement range would be nice (like in UT161).

Overall Rating: ★★★★☆ (4/5)

One end those probes have has a small clip that works with small electronics. The other end fits normal multimeter probes (2 mm diameter probe tips). Those are useful when measuring small ow voltage electronics circuits.

I bought two sets of probe. One set worked flawlessly. The other set the miniature probe sometimes gets stuck down. The one that worked well felt like a quality product.

The product page says “This multimeter test hook is designed for universal compatibility, perfectly suited for various testing devices for diverse application” which I can agree this. Those are useful probes that fit normal multimeter measurements wires.

Another claim is “this test hook functions precisely in demanding and high voltage environments, ensuring superb performance”. I have to a little bit disagree with the high voltage part because I feel that the thin cable and the “DuPont connector” in the end of cable are not safe for high voltage work (like hundreds of volts or more). These are useful for measuring low voltage on electronic devices and circuit boards. The clips connect well to various electronics connections and parts. The”DuPont connector” can also be used without probe tip to connect the cable to circuit board pin header.

Take a look inside the probe. I fixed the probe that was sometimes stuck and took a picture. The hardest part in repairing was to put the parts back together.

Here is a technical drawing from the product page:

R413D08 DC 5V 12V 24V 8ch RS485 Modbus Rtu Control Module for Relay PLC Switch technical data:
1: Operating Voltage : DC 5V(5V Version) / DC 6-24V(6-24 Version)
2: Operating Current : 10-15MA
3: ”open” ”close” ”Momentary” ”Self-locking” ”Interlock” ”Delay” 6 Commands
4: Two instruction-control mode : AT command and MODBUS command
5: Under the AT command ,the maximum delay is 9999 seconds
Under the MODBUS command ,the maximum delay is 255 seconds
6 AT commands can be made serial HyperTerminal (serial assistant) Enter;
MODBUS commands can be made serial HyperTerminal (serial assistant) OR ”Modbus Poll” Enter;
7 Under the MODBUS command mode, it can support up to 247 devices in parallel
8 With RS485 and RS232 (TTL) dual bus interface
9 Output control pins 8, 5V TTL level, low level (default) / high level output
10 Size: 45 * 30 * 15mm
11 Weight: 10g

Function description:
“Open”: Control port outputs low level (default)
“Off”: Control port outputs high level (default)

Here is an application example from R413D08 DC 5V 12V 24V 8ch RS485 Modbus Rtu Control Module for Relay PLC Switch product page:

Here a cheap USB-RS485 converter convers the data from computer to RS-485 format, and the board receives the data.

Modbus controlling

Modbus or MODBUS is a client/server data communications protocol in the application layer. It was originally published by Modicon (now Schneider Electric) in 1979 for use with its programmable logic controllers (PLCs). Modbus has become a de facto standard communication protocol for communication between industrial electronic devices in a wide range of buses and network.

This board supports MODBUS communications. The default communications parameters are 9600 Band ,8 Data bits,None Parity,1 Stop Bit. The default MODBUS slave address is 01.

Here is table from https://github.com/microrobotics/R413D08/issues/1 page that describes the supported MODBUS read commands:

When you read relay state, value 0×0001 means open and 0×0000 means closed.

The MODBUS address can be changed and if it is unknown, it can be read with “Read Slave ID” request: FF 03 00 FF 00 01 A1 E4

Here are the relay control commands:

I found the most useful command to be this direct control commands.
Command 0×06
Address 1-8 relay number
Values:
Open 256 (0×0100)
Close 512 (0×0200)

There are also commands that support more advanced features, for example opening or closing relay after predefined delay time. Under the MODBUS command the timing resolution is one second and the maximum delay is 255 seconds

More command details can be found in manual at https://github.com/microrobotics/R413D08/files/5689915/8.Channel.Multifunction.RS485.Module.command.pdf

AT commands

The Hayes command set (also known as the AT command set) is a specific command language originally developed for controlling modems. The command set consists of a series of short text strings which can be combined to produce commands for operations such as dialing, hanging up, and changing the parameters of the connection. It has been also adapted for other uses as well. In this product the AT command set is used to control the relays.

The module needs to be set to AT command mode to be able to use AT commands. This is done by making M0′s two pads are soldered together or connected with other means.

The communications worked well through RS-485 using TeraTerm terminal program with 9600 8N1 no handshake communications settings and the following terminal settings:

Here is the AT command (ASCII) overview if you want to try to use them:

Read Status:
Channel 1: AT+R1
Channel 2: AT+R2
Channel 3: AT+R 3
Channel 4: AT+R 4
Channel 5: AT+R 5
Channel 6: AT+R 6
Channel 7: AT+R 7
Channel 8: AT+R 8

Open relay:
Channel 1: AT+O1
Channel 2: AT+O2
Channel 3: AT+O3
Channel 4: AT+O4
Channel 5: AT+O5
Channel 6: AT+O6
Channel 7: AT+O7
Channel 8: AT+O8

Close:
Channel 1: AT+C1
Channel 2: AT+C2
etc..

Toggle (Self locking):
Channel 1: AT+T1
Channel 2: AT+T2
etc.

Latch
Inter locking
Channel 1: AT+L1
Channel 2: AT+L2
etc..

Momentary
Non locking )
Channel 1: AT+M1
Channel 2: AT+M2
etc.

Delay
Channel 1: AT+D1=XXXX
Channel 2: AT+D2=XXXX
etc.
XXXX = refers to the 0000 to 9999 figures, Unit is seconds
Under the AT command ,the maximum delay is 9999 second (over 2.7 hours).

Example 1:
Send command
“AT+ 0010 “”, Channel 1 is ” Open “”, after delay of 10 seconds, channel 1 is Close
Send command
” D 2= 0 10 0 “”, Channel 2 is ” Op en “”, after delay of 1 0 0 seconds, channel 2 is Close

Example 2:
Send command
“AT+ L1″, Channel 1 is ” Open “”, other C hannel s is ” Close
Send command
“AT+ L2″, Channel 2 is ” Open “”, other C hannel s is ” Close

More command details can be found in manual at https://github.com/microrobotics/R413D08/files/5689915/8.Channel.Multifunction.RS485.Module.command.pdf

More information

Links to more information:

5V 6-24V RS485 RS232 R413D08 8 Channel (TTL) Modbus RTU Control Module Multi-Function Relay PLC Control Board
https://www.aliexpress.com/i/1005003098396828.html

This RUST project can read and write a R413D08 module from the command line.
https://github.com/acpiccolo/R413D08-Controller/blob/main/README.md

RS485MODBUS V3.O
Software utility for STM8S103, R421A08, R221A04, R413D08 relay board
https://sourceforge.net/projects/rs485modbus/

R413D08
8 Channel Relay Control Module – RS485 & RS232
https://github.com/microrobotics/R413D08

Linux app named RS485modbus
https://www.onworks.net/software/app-rs485modbus

Product R413D08, USB to RS485/RS232 – documentation?
https://github.com/microrobotics/R413D08/issues/1

Product pages:

R413D08 DC 5V 12V 24V 8ch RS485 Modbus Rtu Control Module for Relay PLC Switch
https://www.ebay.com/itm/333654114235

5V 6-24V RS485 RS232 R413D08 8 Channel (TTL) Modbus RTU Control Module Multi-Function Relay PLC Control Board
https://www.aliexpress.com/item/1005003098396828.html

Description:
Specification:
Power Source: DC
Contact Load: Low Power
Voltage: 12V

Modbus RTU instruction
Baud rate: 9600 8 NONE 1

This cheap relay module arrived with no user manual, no operating instructions, no datasheets, and no technical support.

Steps:
1. Software settings communication baud rate
2. Set the address (communication using the device address, the default address is 01)

Modbus RTU instructions
Baud rate :9600 8 NONE 1

Modbus RTU Relay Module article describes 5V version of same type of board. The article list also the following commands to control the relays on the board.

Relay 1 ON = 01 05 00 00 FF 00 8C 3A
Relay 2 ON = 01 05 00 01 FF 00 DD FA
Relay 1 OFF = 01 05 00 00 00 00 CD DA
Relay 2 OFF = 01 05 00 01 00 00 9C 0A

After finishing the command I should get get the corresponding relay click and LED feedback and relay indicator lights up when the relay is ON.

I needed a software to send those codes to the device. The typical normal terminal editors like TeraTerm and Putty are not the right tools to do that. I need something where I can feed those HEX codes and send them out when I need. HTerm is a free terminal program for serial communication running on Windows and Linux. It supports sending messages you define (it accept input in HEX format). I installed to Windows version to a computer that run Windows 10.

The software worked well and my card reacted to most of those commands. Everything except relay one off command worked.

The board tells that it is designed to work with 12V power (it has relays with 12V coils in there). For a short test it seemed to work OK when powered with 9V battery. The relays say that they can control 10A 250V AC or 10A 30V DC. The relay outputs have a changeover contacts (closes one circuit and simultaneously opens a second circuit).

According Modbus protocol description the data packets indicate that the default device address is 1 (0×01) and the relays are controlled with Write Single Coil (0×05) command. The write address for first relay is 0 (0×0000) and for second relay it is 1 (0×0001). The value to write to turn on relay is 0xFF00 and to turn relay off the value to write is 0×0000.

Next test was to try a Modbus test software for controlling the relays. I used a free PowerHud Mobbus Tester softwARE from https://www.modbustester.com/ to test Modbus communications. It worked well and could control both relays.

The module also supports two digital inputs. There was lack of exact technical data on voltage levels they are designed to use and the addresses the information should be read from. But after some testing I found out that the inputs can be rad with Read Discrete Input (0×02) command at addresses 0×0000 for IN1 and 0×0001 for IN2.

The inputs are connected to the power input ground

The inputs seemed to react so that a positive voltage of 0 to 0.6V showed state “off” and voltage of 0.7V to 12V showed state “on”. Due the lack of exact technical data I did not try higher voltage than the device nominal operating voltage. The input circuit seems to consists of a transistor driven with few resistors. I measured that the input takes around 2 mA current when you feed control voltage to it from 9V battery.

Information on other board that look similar but might not be exactly similar:

Modbus RTU Relay Module
https://www.electroschematics.com/modbus/

MODBUS RTU 2 CHANNEL RELAY MODULE FIRST TEST
https://www.youtube.com/watch?v=o5cIF3TRwyg

N4ROB02 2CH Micro Size MODBUS RTU RS485 Relay Board
https://www.youtube.com/watch?v=P0LsmAz_VpU

Modbus-Rtu 2 Relay Outputs 2 Switch Inputs TTL/ RS485 Interface Communication
https://www.fruugo.fi/modbus-rtu-2-relay-outputs-2-switch-inputs-ttl-rs485-interface-communication/p-274194316-608528429?language=en&ac=croud&utm_source=organic_shopping&utm_medium=organic

N4ROB02 2CH Micro Size MODBUS RTU RS485 Relay Board
https://www.youtube.com/watch?v=P0LsmAz_VpU

Modbus RTU 2 Way Relay Module TTL/RS485 Interface Communication with Indicator
https://www.ebay.co.uk/itm/144858429900?chn=ps&_ul=GB&_trkparms=ispr%3D1&amdata=enc%3A1n1VKqhPwR8y76HhajGXCxw84&norover=1&mkevt=1&mkrid=710-169684-076987-9&mkcid=2&itemid=144858429900&targetid=293946777986&device=c&mktype=pla&googleloc=1005576&poi=&campaignid=20646531284&mkgroupid=154544387436&rlsatarget=pla-293946777986&abcId=&merchantid=232722533&gad_source=1&gclid=EAIaIQobChMIgLXm4fPEhAMV-VCRBR0IYgy8EAQYCCABEgLCAfD_BwE

LC 2-way Modbus relay module
http://www.chinalctech.com/m/view.php?aid=455

N4ROB02 2CH Micro Size MODBUS RTU RS485 Relay Board
https://www.youtube.com/watch?v=P0LsmAz_VpU

Parameters:
Product name: temperature and humidity transmitter
DC power supply: DC 5V-30V
Output signal: RS485 signal
Temperature accuracy: ±0.5℃ (25℃)
Humidity accuracy: ±3%RH
Temperature range: 0%RH-80%RJ
Temperature resolution: 0.1℃
Humidity resolution: 0.1%RH
Equipment power consumption: ≤0.2W
Communication address: 1-247 can be set, default 1
Communication protocol: Modbus-RTU protocol and custom common protocol
Baud rate: configurable, default 9600, 8-bit data, 1-bit stop, no parity

This product integrates the MODBUS protocol and the common protocol Using RS485 hardware interface. The user can choose the communication protocol. The product adopts industrial grade chip, high-precision SHT40 temperature and humidity sensor.

Wiring:

My plan was to first test it with Modbus protocol. I wired this sensor to PC using a cheap “no name” USB to RS-485 adapter. For powering the sensor I used 5V from USB port (wired to sensor with cut USB cable).

Here is the overview of the supported Modbus communications protocol.

I think I need to read the temperature and humidity register. To use it I need some software to handle Modbus communications and help testing if it works.

CAS Modbus Scanner is a free proprietary application from Chipkin Automation Systems that I used as first tool to verify that basic Modbus communications works and devices could be found on but. It’s Discover functionality allowed to find that device is there, but for some reason the software did not seem to get successfully data from it.

So it seems that I needed some other tool to make communications work. PowerHud Mobbus Tester from https://www.modbustester.com/ could read the data successfully from the sensor.

How to interpret data info from https://www.aliexpress.com/item/1005001475675808.html

In addition to Modbus protocol, there is another protocol called common protocol. That “common protocol” is a simple ASCII protocol that can be used with any common serial port terminal program. I followed the instructions from XY-MD02 Temp Humidity Serial UART Communication article and video. Here is the most important takeout of special Putty settings in addition to serial port (9600 BPS 8N1) needed to get communications to work:

I got this other protocol to work with Putty program. The READ command reads the temperature and humidity values.

The common protocol has said to have an automatic upload function (connecting RS485 through the serial port adjustment tool will automatically output temperature and humidity). That can be started using command AUTO.

Links to more material:

XY-MD02 Sensor Setting – Modbus RTU Network
https://accautomation.ca/xy-md02-sensor-setting-modbus-rtu-network/

XY-MD02 Temp Humidity Serial UART Communication
https://accautomation.ca/xy-md02-temp-humidity-serial-uart-communication/

https://www.instructables.com/XY-MD02-Temperature-and-Humidity-Sensor-Module-Mod/

Product pages with data:
https://www.aliexpress.com/item/1005001475675808.html

Videos:
https://www.youtube.com/watch?v=V0_IqkWIPG0
https://www.youtube.com/watch?v=e_1QHtkOf6k

Source code links:
https://github.com/TitusSetiawan/XYMD02-ESP32-modbus
https://github.com/cesgarma/modbus-XY-MD02