I got my hands on a clamp multimeter – it measures AC/DC current using a sensor in the jaws, while voltage, resistance, diodes, and more can be measured through the terminals. I was surprised that even a Chinese company is afraid of copying, and the current measurement caught me off guard.
I have written quite a bit about FNIRSI products here – about their soldering pen or USB tester. Now, I have their clamp multimeter in my hands.
I would like to thank FNIRSI DMC-100 for lending me the device, provided by pajenicko.cz. This review is not a paid collaboration!
About FNIRSI DMC-100
FNIRSI DMC-100 is a clamp multimeter – it can measure AC/DC voltage, AC/DC current, resistance, capacitance, frequency, temperature, or diodes. It also features a built-in LED flashlight.
It is also worth mentioning the live wire detection (NCV – non-contact voltage). This is handy for locating wires behind walls.
DMC-100 seems like a compact measuring device that can serve well in a workshop or on the go. Or can it?
My Experience
The controls are simple and intuitive. An advantage is the built-in battery with a large capacity (1500 mAh).
The measured values can be displayed as a number or in a graph – to switch modes, press and hold the MODE button.
A short press of the flashlight button changes the display mode – light/dark (this is never mentioned in the documentation, by the way 🙂 )
A long press of the V-A button (arrow to the right) switches to dual mode – displaying values for both current and voltage.
The measuring cables have sharp tips, making it easy to measure soldered components or test points on a PCB.
Real Measurement – Comparison with Keysight U1252B (calibrated)
1k resistor
DMC-100: 0.996k
U1252B: 0.9968k
1nF capacitor
DMC-100: 0.997nF
U1252B: 1.045nF
Voltage 1V
DMC-100: 1V
U1252B: 0.999V
Voltage 10V
DMC-100: 10.01V
U1252B: 10.003V
Voltage 20V
DMC-100: 20.02V
U1252B: 20.005V
DC current 0.1A
DMC-100: 0.10 – 0.11A
DC current 1A
DMC-100: 0.99A
DC current 3A
DMC-100: 2.93A
And I would like to pause here regarding current measurement.
Current Measurement and Measurement Inaccuracy
DMC-100 measured 2.93 A instead of 3 A.
The inaccuracy (deviation) of the measurement is ±2.5% of the measured value + 10 digits for DC current measurement.
Thus, we can calculate that the measured value could be (for 3 A) off by as much as ±0.173 A.
The measured current of 2.93 A corresponds to the product specification for this measurement range.
Is This Normal?
The current value changes with the tilt of the multimeter.
To be honest, I have very little experience with clamp measuring devices.
I know that measuring current through the jaws (Hall sensor) is not particularly accurate, it can be affected by noise, magnetic fields, and the current in the cable must be placed in the center of the jaws.
The answer: no, this is not unusual behavior.
Even so, I find these deviations of tens of mA interesting – IT IS NOT necessary to take this as an error 😉
You can reset the value (set to zero) with a short press of the on/off button.
Firmware Upgrade
Do you need to update the firmware? Here’s how:
- keep the multimeter turned off
- press the HOLD and SAVE/MENU buttons
- press the power button of the multimeter
- then connect the multimeter to the computer (USB cable)
- drag the *.bin file into the folder, the multimeter will create a “flash drive”
- then press the SAVE/MENU button to start the firmware update process
Calibration
You can also calibrate the clamp multimeter at home.
Before turning on the device, hold both buttons simultaneously and then turn on the device.
The FNIRSI DMC-100 multimeter will then expect defined voltage, current, resistance, and other quantities that you want to calibrate.
WARNING! This calibration can only be performed 5 times!
Thanks for this information to Petr Večeřa, who commented on Facebook.
Is the Chinese Company Afraid of Copying?
While examining this multimeter, I decided to disassemble it and take a look inside.
After removing the cover, a PCB appeared with several microcontrollers. I was very surprised that the names of the chips were removed – milled away.
So you can forget about any proprietary or rather alternative firmware that could be developed for this device.
Moreover, this may also indicate that even Chinese companies are afraid of copying their own products.
Note: I was informed on Facebook…
According to a commenter, “such precise milling would be very inefficient in production (and thus also in cost). In practice, it is often either an area designated for UV marking/modification, or typically a so-called mold mark (trace from the mold). In this case, it looks like a mold mark.”.
So I would like to state that “it is not a mold mark, and I see milling there.”
Conclusion
So I should evaluate the multimeter itself. For me, it is an interesting choice for hobbyists who need to measure tens of Amperes in AC or DC.
At the same time, they will also appreciate the ability to measure voltage, capacitance, or diodes and frequency. The flashlight will certainly come in handy as well.
I was pleasantly surprised by the live wire detection; I really found that cable behind the wall that I drilled into three years ago and knocked off the protector.
P.S. I got a model with the “SAVE/MENU” button :-(((
Datasheet https://cdn.shopify.com/s/files/1/0694/8310/2426/files/DMC-100_User_Guide.pdf?v=1733363686
Product page https://www.fnirsi.com/products/dmc-100?_pos=1&_sid=4abea4883&_ss=r
The price of the DMC-100 is 45.95 Euros + shipping.
I would like to thank FNIRSI DMC-100 for lending me the device, provided by pajenicko.cz. This review is not a paid collaboration!
The price of the DMC-100 is 995 CZK + shipping.
