Aneng 302 Pocket Meter by Voltlog

[malagas_on_fire]

Aneng 302 Pocket Meter Voltlog... uses buttons instead of rotary switch, true rms .. and more... and less of course




Another CAT overated multimeter..

[Candid]

Nice little meter. Only some Cent more and they could have added better input protection. So it is one more of the CAT rating liars around and not usable for mains, what a pitty. Could have been a perfect little meter for the daily bag.

[Fungus]

Nice little meter. Only some Cent more and they could have added better input protection. So it is one more of the CAT rating liars around and not usable for mains, what a pitty.

A 600V CAT II rating looks reasonable for the amount of protection shown in that video and with no current measurement.

I wouldn't call them liars yet - not without some more in-depth testing.

Edit: It looks like a nice little pocket meter. Good continuity tester, very sensitive NCV, flashlight...

I just ordered one.

[HKJ]

A 600V CAT II rating looks reasonable for the amount of protection shown in that video and with no current measurement.

I would guess that one of the small SMD resistors has the full input voltage (CAT II 600V is up to 4000V peak) across it when in ohm and mV mode.

[Fungus]

I would guess that one of the small SMD resistors has the full input voltage (CAT II 600V is up to 4000V peak) across it when in ohm and mV mode.

I obviously wouldn't recommend one of these to an electrician for daily use but I've seen a lot worse.

[HKJ]

but I've seen a lot worse.

The only worse condition (On ohm range) is to leave out the PTC, then the ohms range will be fried on any voltage.
I would expect it is ok to use the meter at CAT II 300V, but not at higher energy levels.

[Fungus]

I would expect it is ok to use the meter at CAT II 300V, but not at higher energy levels.

OK, I'll go with that. 600V is a bit high.

[rsjsouza]

Good review; all it takes to make a more robust meter such as the Sanwa PM300 is a better placement of components and a few extra cents of beefier components...

( shameless plug to my video: https://youtu.be/OlgvAE_jx3w?t=6m39s )

[HKJ]

Good review; all it takes to make a more robust meter such as the Sanwa PM300 is a better placement of components and a few extra cents of beefier components...

The first improvement is to replace the 900k (A guess) SMD resistor with a high voltage part, next improvement is to add a series resistor to the PTC.

[Candid]

Nice little meter. Only some Cent more and they could have added better input protection. So it is one more of the CAT rating liars around and not usable for mains, what a pitty.

A 600V CAT II rating looks reasonable for the amount of protection shown in that video...

I don't think so. I liked what I saw in the video until I saw the input protection. Voltlog shows the little Brymens 22s/27s as comparison and I would pay the additional money for getting a much more secure product that is at least usable for mains measurements and that is credibly labeled.

If you are looking for a little meter for only low voltage usage it's ok but I still think that the CAT rating is fake and that it never has been tested for this. It would cost maybe 2 EUR to make it a reliable product that still would be at a very good price level but it's easier to only print a wrong label on the housing. I do not understand this.

I just ordered one.

I am not ;-)

[Fungus]

If you are looking for a little meter for only low voltage usage it's ok

I am, yes.

but I still think that the CAT rating is fake and that it never has been tested for this.

The two original statements weren't linked. I didn't order one because I thought it was a good meter for mains work (which I don't).

[HKJ]

Here is the 900kOhm resistor that must handle the full input voltage in mV/ohm/etc. mode:



Many cheap multimeters has this design with a small SMD resistor directly connected to the probe in ohm mode.

[Fungus]

Here is the 900kOhm resistor that must handle the full input voltage in mV/ohm/etc. mode:



Many cheap multimeters has this design with a small SMD resistor directly connected to the probe in ohm mode.

Sure, but even if you apply 4kV it's still only milliwatts going through it. The clamping transistors on the other side can handle that while the PTC warms up.

The real problem is if a spark can jump around the input protection.

[HKJ]

Sure, but even if you apply 4kV it's still only milliwatts going through it. The clamping transistors on the other side can handle that while the PTC warms up.

This resistor is NOT protected by the PTC, it is directly connected to the input probe!
At 4kV the power will be 17 watt in that resistor.

The real problem is if a spark can jump around the input protection.

This resistor is probably the place where a spark will jump.

[bugi]

Here is the 900kOhm resistor that must handle the full input voltage in mV/ohm/etc. mode:



Many cheap multimeters has this design with a small SMD resistor directly connected to the probe in ohm mode.

Sure, but even if you apply 4kV it's still only milliwatts going through it. The clamping transistors on the other side can handle that while the PTC warms up.

The real problem is if a spark can jump around the input protection.

With my somewhat limited experience, I had understood that even if the problem isn't always the power, there is still...
a) Small size leading the voltages simply jumping over (or under) the short device (made even worse by possible dirt left from soldering). Not sure if 4kV would be enough in this case (not knowing the pad separation, either).
b) Normal small resistors are typically not rated to handle even short-time multi-kV pulses internally, possibly turning very quickly to something else than resistor. "High-voltage" (i.e. relatively quite expensive) variants might work better, but, would those resistors be of such variants?

[floobydust]

An 0805 resistor is typically rated 150V with 200V overload, but arcs across the ~1.2mm pad spacing above this, at a few kV.
An 0603 resistor is typically rated  50V with 100V overload, but arcs across the ~0.9mm pad spacing above this, at a few kV.

You would need more resistors with larger spacings for the string. MELF parts like SMM 0204 are >2kV pulse rated with 1.7mm pad spacing, so at least three are used in a series string.

These DMM's have a terrible PCB layout, it's student-grade. It's not only the resistor's spacings.
HV jumps between the PCB traces to the ground pour, or to the battery holder, or across the rotary switch, to the fuse holder etc.
The PTC is a mile away from the input jack. They just don't have spacings and clearance required.

Schematic J1-A (PTC path) is (output) for ohms, capacitance, diode test etc.
J1-B (900k ohm path ) is to a comparator for continuity beeper and frequency I think.
The A/D input is after the 10MEG resistor.

[HKJ]

An 0805 resistor is typically rated 150V with 200V overload, but arcs across the ~1.2mm pad spacing above this, at a few kV.

The resistor looks more like a 0603.

[floobydust]

fixed that. Less than a mm spacing is very small.

[HKJ]

I checked a component supplier, they have anti surge 0603 resistor that have a working voltage of 150V and maximum overload voltage of 200V.
For 0805 it is 400V and 600V and 1206 it is 500V and 1000V

Looked at bit more, a YAGEO RV0603 is 350V and 500V

[Candid]

but I still think that the CAT rating is fake and that it never has been tested for this.

The two original statements weren't linked. I didn't order one because I thought it was a good meter for mains work (which I don't).

No problem. What I talked about was:

A 600V CAT II rating looks reasonable for the amount of protection[...]

I wouldn't call them liars yet - not without some more in-depth testing[...]

And reading what floobydust and HKJ are writing makes it even worse. With a little more effort and only some more Cent for security this could have become a really nice DMM for wide range usage. So I think investing in a Brymen 22s e.g. would be the better way.

[floobydust]

ANENG gets fake 61010 approvals. Certificate is only as a 3V battery-powered instrument 
You can lie to approvals agencies and tell them it only reads ohms , runs on a few volts.

[malagas_on_fire]

Hi

Here is the inside of the uni-t ut210c, with a PTC, melf resistors a couple of m7 diodes , clamps, a ton of capacitors and its not that expensive, but has 10nF drift on capacitor mode that needs to be REL out,  continuity test is poor, slow.