New ANENG multimeter

[Mark Hennessy]

Yes, with the AC+DC case, it's definitely the auto-ranging not doing the right thing - see previous posts for a variety of speculation as to what's happening, but whatever the real answer, you can at least appreciate that it's a lot more complex and there is scope to get something wrong. But in the case of raw AC with no DC offset, I'm really struggling to imagine what could be going on. Let's hope we won't see that one again

If you can reproduce it, as well as removing and re-connecting the signal, it's also worth connecting it via a capacitor (10n should be fine - watch the voltage though!) to remove all DC component. Sometimes the mains has a small DC component because of distortion...

[glarsson]

The DC component of the mains (as shown by the AN8002) was not stable and jumped around below 0.5V.

[tronde]

Does anyone have a link to the original datasheet? Kerry Wong's translation is great, but I'd like a better look at the diagrams which are rather low-res in the PDF.

Spend some time on the HY12P65 as well. It is believed to be the processor used in DTM0660.

http://www.hycontek.com/en/products-en/3256

[floobydust]

Does anyone have a link to the original datasheet? Kerry Wong's translation is great, but I'd like a better look at the diagrams which are rather low-res in the PDF.

Spend some time on the HY12P65 as well. It is believed to be the processor used in DTM0660.

http://www.hycontek.com/en/products-en/3256

I believe Dream Tech does the application firmware for DMM's based on the Hycon HY12P65. I'm not sure who EEVblog is working with for the new DMM's firmware.
You can run the 660 datasheet .pdf through google translate, it seems to do better than Kerry Wong.

The AN8008 DMM IC appears the same as the HY12P65 but with more (or fudged)  A/D resolution and the support for external voltage reference.
chinese forums are saying the COB version is low quality (for export) compared to the QFP packaged part (domestic use).

[MacMeter]

The bug being discussed occurs when you have a mixture of AC and DC present at once.

One of my two AN8002 shows incorrect AC without any (significant) DC.  Select V and AC. Put probes into 230V AC outlet. Display shows 234VAC (or similar). Toggle to DC; display shows 0VDC. Toggle to AC; display shows 2VAC.

Looks more like a bug when switching between AC and DC, with or without an DC voltage present.

Just tested my ZT102/8002, on a USA 120 volt mains outlet. Shows 120 volts AC, and switching to DC mode, shows 0.19, but I can switch back to AC, still shows 120 volts, same if I remove and replace leads.

BTW: ZT102/8002 backlight stays on for less then 15 seconds, on the ZT109/8008, backlight stays ON for approximately 2 minutes, much better!

[kalel]

I also got my AN860B+ as DM400. I'm wondering, is there any way to turn the beep beep between selecting ranges off? As useful as it is, I want to preserve the batteries and sometimes don't want the beep sound if possible.

Second, could it be that my batteries are not good enough (new, but cheap) or is the contrast worse than DT830D? With the backlight, it looks great, but without, it's a bit less pronounced. It's completely usable, though.

I tried picturing it, but it looks a bit different on photos, and it's not easy to get a good comparison photo. But the DT830D definitely has great contrast from all angles. No backlight though, maybe it's related?

Edit: Here's an attempt to image it from a similar angle (straight):

The issue here is that I can't fully turn the auto adjusting off. So, the levels will not be equal. But, they are almost representative of the difference when looking straight at the screens. Both visible, but DT more pronounced.

As others have mentioned before on the Aneng brand, it also comes with the mark below the off switch.

[MrPCB]

I believe I saw that one on vitechparts.com
Can't find it anymore though, might be mistaking.

It looks pretty good to me!

[kalel]

I believe I saw that one on vitechparts.com
Can't find it anymore though, might be mistaking.

It looks pretty good to me!

Which one is that?

[kalel]

I'm also adding some images of the probes with others for comparison:

AN860B+ / DM400:


It's not easy to keep these stable, but the best I was able to get is 0.1 - 0.3 ohms. That should be fine.

Old Mastech probes (came with a badly working $10 unit - using now on DT830D):


When held firmly together, these show 0.0 ohm on the DM400. On the DT830D it starts from around 3 ohms and decelerates for a long time.
I had to "repair" the DT830D input jacks, as voltage one was broken. Might be partly the cause of the different reading.

Cheap $2.5 analog multimeter probes (MF-110A):


Finger test also shows that Mastech are the sharpest probes of the bunch. I'm no expert in probes, so I can't provide any more feedback from the images. If you've noticed something else about the construction differences, let us know.

Also, both Aneng and $2.5 multimeter probe pairs seem to have the some differences between each other. Those differences are less noticable on the Mastech ones (after a few years, slight wear might have some effect on the shape too). But this is likely not important in normal use (how symmetrical the probes are).

[Fungus]

the DT830D definitely has great contrast from all angles. No backlight though, maybe it's related?

I often wonder why big manufacturers like Fluke/Brymen/etc. can't get their LCDs as good as the freebie DT830Bs. 

(can anybody explain it?)

[kalel]

the DT830D definitely has great contrast from all angles. No backlight though, maybe it's related?

I often wonder why big manufacturers like Fluke/Brymen/etc. can't get their LCDs as good as the freebie DT830Bs. 

(can anybody explain it?)

You get instantish beeping too (not on the B version). Unfortunately, it's the lack of latching that makes the fast response. Still, you could get somewhat higher frequency continuity beeping if needed in some special case.

That said, this an860b+ / dm400 has really great continuity. Definitely seems fast enough for my use, and there's no scratching. Not that scratching was a major issue on the DT, unless it really annoys you.

[floobydust]

the DT830D definitely has great contrast from all angles. No backlight though, maybe it's related?

I often wonder why big manufacturers like Fluke/Brymen/etc. can't get their LCDs as good as the freebie DT830Bs. 

(can anybody explain it?)

I can try explain. The DT830 appears to use 9VDC power and direct-drive (no multiplexing) ala ICL7106. This is pretty much the highest LCD contrast you can get.

The DMM0660 used in most meters runs off less with 3VDC. But has a LCD charge-pump inverter which is programmable with 4 LCD bias levels, at EEPROM F9H: 3.3V, 3.05V, 2.8V, 2.55V. The meters come set to level 3/4. I have not tried cranking it up or if I translated this properly.

So you get ~6V drive to the LCD but it uses multiplexing 1/4 duty cycle 1/3 bias, to cut down the pin count, so again you lose contrast there.

Extended temperature LCD fluids, good to -20C or -30C require high drive voltage and more finicky with temperature, you'd need a pot to keep adjusting it.

[kalel]

the DT830D definitely has great contrast from all angles. No backlight though, maybe it's related?

I often wonder why big manufacturers like Fluke/Brymen/etc. can't get their LCDs as good as the freebie DT830Bs. 

(can anybody explain it?)

I can try explain. The DT830 appears to use 9VDC power and direct-drive (no multiplexing) ala ICL7106. This is pretty much the highest LCD contrast you can get.

The DMM0660 used in most meters runs off less with 3VDC. But has a LCD charge-pump inverter which is programmable with 4 LCD bias levels, at EEPROM F9H: 3.3V, 3.05V, 2.8V, 2.55V. The meters come set to level 3/4. I have not tried cranking it up or if I translated this properly.

So you get ~6V drive to the LCD but it uses multiplexing 1/4 duty cycle 1/3 bias, to cut down the pin count, so again you lose contrast there.

Extended temperature LCD fluids, good to -20C or -30C require high drive voltage and more finicky with temperature, you'd need a pot to keep adjusting it.

Interesting. It would be nice if there was a contrast setting built into the meter, so you could adjust it with a button (probably along with other things such as auto shutdown time, backlight settings, etc). I wanted to say I don't see any reason not to include such extra settings, but perhaps having too many options with only a few buttons is a good reason. Although some "special settings" that aren't used frequently could probably be done with special key combinations, so that there's no intrusion on standard usability.

[Fungus]

Interesting.

OK, I get the technical aspects but that still doesn't explain why they can't increase the LCDS voltage boost to get an extra volt (or whatever).

It would be nice if there was a contrast setting built into the meter, so you could adjust it with a button (probably along with other things such as auto shutdown time, backlight settings, etc).

I remember back in the 1980s every electronic gadget with LCD had this.

[kalel]

Speaking of low voltage, I measured the battery of one room temperature meter (the cheap ones), and seems to be 2 1.5v in parallel.
Even if it was in series, that would still be ~3v which is similar to two AA batteries in series.

The contrast is very strong, exactly the same as the DT.

[Fungus]

Speaking of low voltage, I measured the battery of one room temperature meter (the cheap ones), and seems to be 2 1.5v in parallel.
Even if it was in series, that would still be ~3v which is similar to two AA batteries in series.

The contrast is very strong, exactly the same as the DT.

Dave did a whole video on hacking his own Brymen meter to get decent contrast. It's just a resistor selection, but ... Brymen got it wrong.

[kalel]

I would also add that you should take a lot of care of the display cover.

I already see a light (but visible enough to be slightly annoying) scratch on mine after just a few uses. Not sure what caused it exactly, but I wish I knew earlier exactly how delicate it was (e.g. I think the DT doesn't have any protection, but can stand a lot more). I doubt we can get replacements for these.
I also don't dare to try some polish methods, otherwise I might end up with a semi-transparent display.

[edavid]

I would also add that you should take a lot of care of the display cover.

I already see a light (but visible enough to be slightly annoying) scratch on mine after just a few uses. Not sure what caused it exactly, but I wish I knew earlier exactly how delicate it was (e.g. I think the DT doesn't have any protection, but can stand a lot more). I doubt we can get replacements for these.
I also don't dare to try some polish methods, otherwise I might end up with a semi-transparent display.

If it's soft enough to scratch that easily, it will also be very easy to polish.  Try some toothpaste.

(Use a soft cloth, not a toothbrush.)

[kalel]

I would also add that you should take a lot of care of the display cover.

I already see a light (but visible enough to be slightly annoying) scratch on mine after just a few uses. Not sure what caused it exactly, but I wish I knew earlier exactly how delicate it was (e.g. I think the DT doesn't have any protection, but can stand a lot more). I doubt we can get replacements for these.
I also don't dare to try some polish methods, otherwise I might end up with a semi-transparent display.

If it's soft enough to scratch that easily, it will also be very easy to polish.  Try some toothpaste.

Thanks for the tip, but before attempting I would need to learn more (I haven't actually polished any scratches before).
Just for a test, I tried once polishing a piece of a transparent soft plastic material (nothing valuable) using a toothbrush and some toothpaste. Maybe I shouldn't have used the toothbrush but some really really fine material? Anyway, the result was I got a perfectly nice "diffused" plastic which might be a great thing for some LED projects (good to know). But for a multimeter display, it would be pretty much ruined if the same happened.

[Fungus]

I would also add that you should take a lot of care of the display cover.

I already see a light (but visible enough to be slightly annoying) scratch on mine after just a few uses. Not sure what caused it exactly, but I wish I knew earlier exactly how delicate it was (e.g. I think the DT doesn't have any protection, but can stand a lot more).

I always cut a phone screen protector to shape and stick it on my meters.

[kalel]

I always cut a phone screen protector to shape and stick it on my meters.

That's what I did. I got a bundle in the final days of Dick Smith closing for 10 cents each.

Yes, I'm going to do that too, but I just wish I was able to do it before the damage.
Still, it's much better now than it could be in the future.

[ebastler]

I tried once polishing a piece of a transparent soft plastic material (nothing valuable) using a toothbrush and some toothpaste. Maybe I shouldn't have used the toothbrush but some really really fine material? Anyway, the result was I got a perfectly nice "diffused" plastic which might be a great thing for some LED projects (good to know). But for a multimeter display, it would be pretty much ruined if the same happened.

Indeed -- toothpaste is fine, but use it with a soft cloth, not a toothbrush! The paste contains some mild abrasive; the bristles of the brush are not that mild...

[Fungus]

Indeed -- toothpaste is fine, but use it with a soft cloth, not a toothbrush!

Or just use your finger. That way you can feel what's happening.

[Bud]

Unless you want to experiment, there is variety of plastic polishing paste products in hardware stores and automotive sections, , they work well.

[kalel]

Thanks for the tips everybody. Yes, the brush method is good for diffusing soft plastic (e.g. light cover), but definitely not fine polishing, as one could expect.

I can still live with it at this point since it's relatively mild. If it gets worse enough before I can find a screen protector to apply, I'll try the polish method. It always feel risky, although I can first get some pieces of soft plastic to experiment on as before (always a good idea).

Other than that sensitivity, I'm really enjoying the meter so far. It's my first step up from DT830D (~$3 one that does have continuity tester, but not temperature), and the reading response is very rapid (e.g. measuring resistance and getting the value).

I hooked it up to some potentiometers, and autoranging has no problems switching quickly between ranges.

Continuity works great too, although I never had problems with the small DT there. It doesn't latch, but that means very little lag.

Btw Fungus, did you decide to buy that mini Aneng in the end? The one even smaller than DT.