Aneng 302 Pocket Meter by Voltlog - Page 1
Forum section: electronics / testgear

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: August 08, 2018, 10:50:26 pm
content: Aneng 302 Pocket Meter Voltlog... uses buttons instead of rotary switch, true rms .. and more... and less of courseAnother CAT overated multimeter..

author: Candid
author_rank: Regular Contributor
timestamp: August 09, 2018, 06:26:40 am
content: 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.

author: Fungus
author_rank: Super Contributor
timestamp: August 10, 2018, 03:41:30 pm
content: Quote from: Candid on August 09, 2018, 06:26:40 amA 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,verysensitive NCV, flashlight...I just ordered one.

author: HKJ
author_rank: Super Contributor
timestamp: August 10, 2018, 03:53:45 pm
content: Quote from: Fungus on August 10, 2018, 03:41:30 pmI 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.

author: Fungus
author_rank: Super Contributor
timestamp: August 10, 2018, 05:09:45 pm
content: Quote from: HKJ on August 10, 2018, 03:53:45 pmI obviously wouldn't recommend one of these to an electrician for daily use but I've seen a lot worse.

author: HKJ
author_rank: Super Contributor
timestamp: August 10, 2018, 05:32:47 pm
content: Quote from: Fungus on August 10, 2018, 05:09:45 pmThe 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.

author: Fungus
author_rank: Super Contributor
timestamp: August 10, 2018, 06:56:24 pm
content: Quote from: HKJ on August 10, 2018, 05:32:47 pmOK, I'll go with that. 600Visa bit high.

author: rsjsouza
author_rank: Super Contributor
timestamp: August 10, 2018, 07:32:22 pm
content: 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)

author: HKJ
author_rank: Super Contributor
timestamp: August 10, 2018, 07:40:08 pm
content: Quote from: rsjsouza on August 10, 2018, 07:32:22 pmThe 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.

author: Candid
author_rank: Regular Contributor
timestamp: August 10, 2018, 08:28:17 pm
content: Quote from: Fungus on August 10, 2018, 03:41:30 pmI 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.Quote from: Fungus on August 10, 2018, 03:41:30 pmI am not ;-)

author: Fungus
author_rank: Super Contributor
timestamp: August 11, 2018, 09:52:52 am
content: Quote from: Candid on August 10, 2018, 08:28:17 pmI am, yes.Quote from: Candid on August 10, 2018, 08:28:17 pmThe two original statements weren't linked. I didn't order onebecauseI thought it was a good meter for mains work (which I don't).

author: HKJ
author_rank: Super Contributor
timestamp: August 11, 2018, 12:39:19 pm
content: 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.

author: Fungus
author_rank: Super Contributor
timestamp: August 11, 2018, 12:55:28 pm
content: Quote from: HKJ on August 11, 2018, 12:39:19 pmSure, 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.

author: HKJ
author_rank: Super Contributor
timestamp: August 11, 2018, 01:33:15 pm
content: Quote from: Fungus on August 11, 2018, 12:55:28 pmThis resistor isNOTprotected by the PTC, it is directly connected to the input probe!At 4kV the power will be 17 watt in that resistor.Quote from: Fungus on August 11, 2018, 12:55:28 pmThis resistor is probably the place where a spark will jump.

author: bugi
author_rank: Regular Contributor
timestamp: August 11, 2018, 01:51:13 pm
content: Quote from: Fungus on August 11, 2018, 12:55:28 pmWith 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?

author: floobydust
author_rank: Super Contributor
timestamp: August 11, 2018, 03:10:19 pm
content: 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 likeSMM 0204are >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.

author: HKJ
author_rank: Super Contributor
timestamp: August 11, 2018, 03:20:17 pm
content: Quote from: floobydust on August 11, 2018, 03:10:19 pmThe resistor looks more like a 0603.

author: floobydust
author_rank: Super Contributor
timestamp: August 11, 2018, 03:23:02 pm
content: fixed that. Less than a mm spacing is very small.

author: HKJ
author_rank: Super Contributor
timestamp: August 11, 2018, 03:34:28 pm
content: 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 1000VLooked at bit more, a YAGEO RV0603 is 350V and 500V

author: Candid
author_rank: Regular Contributor
timestamp: August 11, 2018, 03:50:12 pm
content: Quote from: Fungus on August 11, 2018, 09:52:52 amNo problem. What I talked about was:Quote from: Fungus on August 10, 2018, 03:41:30 pmAnd 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.

author: floobydust
author_rank: Super Contributor
timestamp: August 11, 2018, 03:58:06 pm
content: ANENG gets fake 61010 approvals. Certificate is only as a 3V battery-powered instrumentYou can lie to approvals agencies and tell them it only reads ohms , runs on a few volts.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: August 11, 2018, 09:22:50 pm
content: HiHere 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.