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With its price of approximately € 4.50, this digital meter is undoubtedly one of the cheapest multimeters you can buy. The specifications are excellent: an accuracy of 0.8 % for DC voltages. In this article this miniature gem is tested on all specifications. |
Introduction to the Aneng Type 180
The delivery
Of course you can only order this meter directly in China for the mentioned price. This multimeter is, sloppy packed in a sheet of bubble wrap, delivered in a piece of black plastic film. Not exactly the most reliable way to send measuring equipment from China to the rest of the world!
The bubble wrap contains the meter, two 70 cm long measuring leads and a short English manual. Not included is the necessary 12 V battery. That is a small problem, because you do not buy such a battery in the supermarket around the corner. It is a type 23A alkaline battery that with some luck you can find in a photo shop or that you have to order by mail order in an electronics shop.
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| What is delivered for € 4.50. (© 2018 Jos Verstraten) |
The universal meter is only 10.0 cm high, 5.0 cm wide and 2.3 cm deep. Despite these small dimensions, the meter is easy to read thanks to the LCD display with digits of 11 mm in size. With the one 27 mm rotary switch you can set the measuring range. The switch clearly clicks into one of the nineteen available measuring ranges. The twentieth position is the OFF position, where the battery is disconnected from the electronics. Under the rotary switch are three 4 mm sockets, from left to right COM, V/Ω and mA/BAT. Below the display on the right is a double transistor socket with E/B/C/E connections for both PNP and NPN. The two test leads are well insulated and very flexible.
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| The appearance of Aneng Type 180. (© 2018 Jos Verstraten) |
All parts on the double-sided PCB are sub-miniature SMDs, including the current sensor resistors for measuring currents. This is not a problem, because in the highest measuring range (200 mA) a power of only 0.04 W is generated in the 1 Ω resistor.
More interesting is that the manual says that the meter is fused with a fuse of 250 mA, but that this part cannot be discovered anywhere. So if you mistakenly set the meter to a current range when you measure a voltage, it is probably the end of the device. The SMD resistors will then work as a fuse.
Only one diode can be detected, wwhich proves that measuring of AC voltages has not received much attention.
The big round thing is the buzzer that you can switch on to measure continuity. On the right side you can see an etched connector array that connects the print to the display via conductive rubber strips.
There is only one adjustment potentiometer of poor quality present, which apparently adjusts the entire meter. This means that the accuracy of the various measuring ranges depends entirely on the precision of the SMD resistors used.
As is nowadays the case with almost all multimeters, this design also opted for a cheap switch that is etched on the PCB. The PCB tracks of this switch are gold-plated. The contacts at the bottom of the the rotary switch are also gold-plated.
The 4 mm sockets consist only of a round piece of brass, which is soldered directly to the PCB. The same goes for the two battery clamps.
As the picture below shows, there has been quite a lot of human intervention in the soldering process of the PCB. At several places you can clearly see that the soldering was done by hand.
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| The two sides of the PCB and the bottom side of the rotary switch. (© 2018 Jos Verstraten) |
The fifteen measuring ranges are summarised in the table below. What is striking is that you cannot measure alternating current with this meter. An acceptable limitation, because how often do you measure alternating currents in practice? The two alternating voltage ranges are also a good compromise. The manual states that the meter has a 10 A DC position. That is not the case!
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| The fifteen basic measuring ranges summarised. (© 2018 Jos Verstraten) |
- Battery test 1.5 V
This mode measures the current supplied by a 1.5 V battery. If the battery is good, it should be about 40 mA. Why measure the current and not the cell voltage? A strange decision! - Battery test 9 V
Same for 9 V batteries with a load current of about 25 mA. - Diode test
The meter measures the conductive voltage of the diode with a diode current of 1 mA. - Gain factor hFE
The DC voltage amplification factor of an NPN or PNP transistor is measured with a base current of 10 μA. - Buzzer
The meter will buzz when the resistance between the terminals is less than 30 Ω.
The specified inaccuracy
According to the manufacturer, the meter has the following inaccuracies:
- DC voltage: ±(0.8 % + 1 digit)
- DC current: ±(1.0 % + 2 digit)
- AC voltage: ±(1.5 % + 10 digit)
- Resistance: ±(1.0 % + 3 digit)
The Aneng Type 180 on the test bench
Comparing with a reference meter
When testing multimeters, the question always arises what is used as a reliable reference. Ideally, the use of an adjustable calibrated voltage reference would be ideal, but such a device is far too expensive. We have taken our own half year old laboratory meter as a reference. That is a VC650BT from Voltcraft with a guaranteed inaccuracy of ±0.05 % when measuring DC voltages. When measuring the other quantities of electronics, this meter has also an inaccuracy that is a factor ten lower than the Aneng Type 180.
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| The Type 180 is compared to the 45 times more expensive VC650BT. (© 2018 Jos Verstraten) |
Because you measure voltages in the range up to 20 V most often in daily practice, we have concentrated on testing the inaccuracy of this measuring range. Via an accurately adjustable digital power supply, we set the Aneng readout to round numbers and compared it to what our Voltcraft thought of it. The input resistance of the meter is 997 kΩ on all DC voltage ranges. The measurement results summarized in the table below show that the Aneng performs excellently. With the specified inaccuracy, the meter should not deviate by more than ±0.152 V when measuring 19.00 V. Our example deviates only 0.030 V.
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| The measurement results for DC voltages: excellent! (© 2018 Jos Verstraten) |
In practice, you will most often measure currents up to 200 mA, which is why we have tested this measuring range. Our power supply can be set as a digitally adjustable current source. A series circuit of power supply, Aneng and Voltcraft is quickly made with four test leads. These results are also not disappointing. With the specified inaccuracy, the Aneng should not deviate more than ±3.8 mA when measuring a DC current of 190 mA. Our test sample deviated only 2.43 mA. The internal resistance of the tested meter in this measuring range is 1.02 Ω.
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| The Aneng is also a reliable meter for measuring direct currents. (© 2018 Jos Verstraten) |
Unfortunately, we do not have an adjustable AC power supply. The only sources we can use are the mains voltage and our function generator.
- The mains voltage
The Aneng indicated a value of 228 V, the VC650BT a value of 229.13 V. That is definitely excellent. - The function generator
At a frequency of 50 Hz we set the output voltage until the Aneng indicated 6.00 V. The Voltcraft claimed 6.443 V. This is a percentage deviation of 6.9 %, much more than the specified ±1.5 %.
The frequency range
Interesting is of course the frequency range of the meter. The manual indicates a range from 50 Hz to 200 kHz without specifying the increase in inaccuracy. Of course, we were able to test this with our function generator as a signal source, using a voltage of 6.0 V at 50 Hz as a reference. Afterwards the frequency was increased with a constant amplitude. This was checked on an oscilloscope that was connected parallel to the Aneng. The results are shown in the graph below. The specified 200 kHz is absolutely not reached!
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| The frequency range at a sine wave voltage of 6.0 V. (© 2018 Jos Verstraten) |
To measure resistance, a number of trimpotentiometers were connected in series and the axes were turned until the Aneng indicated round numbers. Afterwards this meter was removed and replaced by the reference meter. Connecting both meters in parallel is not possible when measuring resistors.
The maximum measuring current is 2.26 mA in the 199.9 Ω range.
These results are also impressive, see the table below. The Aneng Type 180 also succeeds in measuring resistors with flying colors!
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| Measuring resistors with both multimeters. (© 2018 Jos Verstraten) |
This position is intended for testing the conductivity of a connection. The built-in buzzer will buzz when the measured resistance is less than 30 Ω. The display shows the resistance of the measured connection in ohm. We tested this function with a number of wire-wound power resistors with very low values, which we measured accurately with Ohm's law. Send a known current through the resistor and measure the voltage over it. Those results are very good, see table below.
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| Measuring very small resistors with the Type 180. (© 2018 Jos Verstraten) |
General conclusion
We were rather sceptical when we ordered this meter. What kind of quality can you expect for a price of less than five euros? As our test progressed, however, we became more and more enthusiastic about the Aneng Type 180. For measuring direct voltages, direct currents and resistors in the hobby lab, you can't wish for a better universal meter. And let these be the quantities you usually measure in practice! For measuring alternating voltages, this meter is less suitable because of the rather large inaccuracy and the limited bandwidth.
ANENG-Mini-Digital-Multimeter-with-Buzzer
