DMM Aneng AN8009



This is the latest incarnation (Late 2017) of the this small fairly cheap meter.



It did not include a box, but was delivered in an envelope that contained the holster.



Everything was inside the holster.



It included the DMM, two pair of probes, a thermosensor and a manual.




The standard probes has removable tip covers.



The other set of probes feels rather low quality, but has some nice functions. They consist of two wires with threads at both ends and a couple of different tips that can be mounted in each end. It is slow to use, but very flexible.








Here are all the different tips.




The thermosensor is a real probe, not just the small bead at the end of wires. The plastic has a crack.
I am not convinced that this is better than the bead, that is smaller and easy to stick on just about to any surface with some sticky tape (Buying one as supplement is cheap).



The body of the DMM feels solid, the plastic is rather smooth, i.e. the DMM can easily slide on a surface. The tilting bale is rather flimsy and do not give enough support for pressing buttons and turning the range switch.














Display



The above picture shows all the segments on the display.
Not all the segments are used on this meter.



Typical display during usage, it will show the number and what measurement is selected.



Non contact voltage will show from one to four bars depending on the electric field strength.


Functions



Buttons:

• Range (Blue): Will disable auto range and change range, hold down to activate background light.
• Sel/Hold (Yellow): Select the ranges printed with yellow, hold down to freeze the display reading.

Rotary switch:

• Off: Meter is turned off
• V % Hz: Show voltage, using the yellow button will cycle between VDC, VAC, freq. and duty cycle.
• mV: Show millivolt, using the yellow button will cycle between VDC, VAC, Celsius and Fahrenheit
• 100Mohm: Resistance, continuity, diode and capacitance, work up to 99.99Mohm
• Hz: Frequency and duty cycle, this is used for lower voltages and works at fairly high frequencies.
• A mA: Current AC and DC (The meter is missing some mA ranges).
• uA: Low current AC and DC.
• NCV: Non contact voltage.

Input

• A mA: A very low burden voltage mA range and a 10A that cannot really handle 10A.
• CON: The common terminal for all ranges.
• xxx: All other ranges, including uA. It is always problematic when a current range shares connector with a voltage range, if the switch is in the wrong position the (hard to replace) fuse will blow (at least). This will only affect current, voltage will still work.

Standard probes will work, but can not be fully inserted.


Measurements

• Volt and frequency
  • 1 VAC is 5% down at 2.1kHz (RMS will not work at the frequency).
  • At 1Vrms input frequency range is from 1Hz to 6.6MHz
  • Input impedance is 10Mohm to 11Mohm on DC and AC
  • mV range is high input impedance for DC up to about 1.5V, then it drops to 3kohm, mV AC is similar, except it is capped by a 10Mohm resistor.
  • Frequency input needs about 250mV to work at 1kHz.
  • Frequency counter and duty cycle works without zero crossing in Hz range.
  • Duty cycle works from 2% to above 99% at 100kHz with 2Vpp (1Vpp do not work), precision is within 0.8 (About 0.8 too low).
  • Frequency input is 10Mohm resistance up to about 12 volt, then it drops to 3kohm
• Current
  • 9.9A range is badly calibrated at high current.
  • 9.9A range will change some percent at 5-10A current due to heating.
  • 9.9A range will give an audible alarm when current is above 9.9A (uA will not).
  • Current ranges are limited to 36VDC and 25VAC.
  • uA range is protected with 0.2A/250V 3.6x10mm fuse
  • AmA range is protected with 10A/250V 3.6x10mm fuse
• Ohm, continuity, diode and capacitance
  • Ohm needs about 2.6s to measure 100ohm
  • Ohm voltage is 1.0V open and 0.38mA shorted
  • Continuity is very fast (About 4ms).
  • Continuity beeps when resistance is below 50ohm.
  • Continuity is 1.0V open and 0.38mA shorted
  • Diode voltage is 3.2V with display of up to 3.000V with 0.14mA, maximum current is 1.6mA shorted
  • 70000uF takes about 9 seconds to measure.
• Miscellaneous
  • A beeper will sound shortly before the meter turns itself off
  • Current consumption of meter is 1.6mA to 2mA (8.7mA with backlight)
  • Meter works down to 2.2V where it turns off, battery symbol show at 2.4V.
  • Readings are stable with changing battery voltage.
  • Backlight only works down to about 2.6V where it is fairly dim.
  • Viewing angle is good.
  • Display updates around 3 times/sec
  • Backlight will automatic turn off in about 120 seconds.
  • Will automatic turn power off in about 15 minutes.
  • The meter usual need a couple of display update to reach the final value.
  • Weight is 136g without accessories, but with batteries.
  • Size is 130.4 x 65 x 32.3mm
• Probes
  • Probe resistance 55mOhm for one.
  • Probe wire is fairly soft and 65cm long.
  • The probes with replaceable tips has 55mOhm with 4mm plug.
  • The probes with replaceable tips has 87cm long fairly soft wires.

A look at the capacitance measurement waveform.



Frequency input resistance.






Tear down



Four screws and the back could be removed.




The circuit board is shaped to fit the enclosure.



3 more screws and two clips, then I could remove the circuit board from the front.



And two more screws and two more clips to remove the display.
As usual the connection to the display is with a zebrastipe and there are two wires for the backlight.



There is not much on this side, only the switches and the connector pads for the display.



Everything is on this side. Near the 10A fuse (F1) is the uA shunt (R23 & R24: 99ohm+1ohm), this shunt is protected by a diode (D5) and a 200mA fuse (F2).
The voltage input is handled by two resistors (R29 & R20: 5Mohm+5Mohm) and there is a small PTC (PTC1) for protecting the ohms/capacitance current output. The two transistors (Q3 & Q4) is protection after the PTC.
The part marked Q5 is a ICL8069 1.2V reference and Q1 is used to turn the background light on and Q2 the buzzer.
There is a EEPROM (IC1: 24C02A) to handle calibration and define function in the multimeter, the big blob is the main multimeter IC.
There is a trace at the top of the circuit board between the two LCD mounting holes, that is the NCV antenna.












Conclusion

The meter is easily within the specified tolerances (Except 10A) and it has lot of functions and ranges, but the CAT rating is fake.

This is a small DMM in size, but has most of the expected functions in a universal DMM. It has a hole in the current range, it can measure currents in that range, but with fairly low precision, instead it has very low burden voltage in the mA range and low precision at high current. Temperature and NCV is a good addition to this version of the meter.

I do not like the small fuse size, they cannot break high voltage or high current and they can be hard to source locally (They can be found on Ebay). The current range on the voltage input is also a bad idea.

The 9999 count secures the best possible resolution for 4 digits.

I will call it good DMM for hobby use, but keep it away from anything with mains voltage and lots of amps.





Notes

This meter may exist with many different names on it and small variations in functions.

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