AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter

[Mr. Scram]

Could someone compare the frequency the buzzers are running at?  Loud vs Quite.  Perhaps they started using different batch of buzzers that require a different frequency, even 500Hz off make a huge difference.

The frequency seems to be exactly the same, with the main frequencies being slightly under 2 KHz and 4 KHz. The first figure shows both waveforms overlaid. This shows the frequencies to be the same, but the amplitude very different. The waveform may be slightly different too, but to my ear with voided calibration, they sound very close. The two other plots show the spectrum of both beeps separately.

[flywheelz]

@Mr. Scram, nice work!  Then the problem is lack of power.  Perhaps they've used a higher value current limiting resistor for the buzzer, if there is one.

[ceut]

@Mr. Scram, nice work!  Then the problem is lack of power.  Perhaps they've used a higher value current limiting resistor for the buzzer, if there is one.

I've put a 39 Ohms in series with the buzzer, because it was too loud for me 
The buzzer is driven by Q2 directly from the MCU, at a fixed frequency of 1.95kHz (datasheet of the DTM).
My buzzer has 50 Ohms impedance - Maybe the impendance can be a little different from DMM to DMM.

I have also put another 39 Ohms in series with backlight Led.

So I think my mod are a little battery-saver 

Also I've done all my calibrations manually in the Eeprom (moving the hexa values) and now I find it nearly perfect for me 

[Crumble]

[...]

a) If it's always used correctly on the AC setting then probably nothing spectacular will happen. Safety features are for when you mess up, right?

b) If it simply dies a quiet death then "Crappy China" will be blamed, not the person who chose the meter.

I wouldn't be too sure about that.

a) Yes and no, when you are measuring mains, there is probably something going on there. Let's say a contactor is malfunctioning intermittently and creates inductive peaks upon disconnecting. Despite the high voltages possible these are usually quite innocent in energy content. They may however be able to initiate an arc within your meter (if the internal clearances are too small) that is then fed by the mains current which is capable of 1000s of Amps before any safety trips. That is why the CAT ratings require testing with voltage transients way beyond the voltage rating they test for (8kV for a CAT IV 600V meter for example). These occurrences aren't actually that likely, but only one such an event is able to kill you so I'd try to prevent it when feasible. Fluke has published a document with a simplified explanation of the things that can go wrong. You might like the explanation of mjlorton too.

b) If not, you will die a loud one, and then it might be less relevant who is to blame. You should watch the older videoblogs of Dave's if you have the time. I can recommend EEVblog #6 part 2. I do disagree with Dave in his crusade against anything cheap, but in this episode he does elaborate quite well (but not too long) about why a cheap multimeter would not suffice and makes some excellent points that hold today (8 years later). There was one with him emphasising about the UL listing, but I could not find it in the 1220 odd blogs he made. Bottom-line is that a CAT rating is only worth anything if it is independently tested, else it is no more than a claim of the manufacturer.

[GreyWoolfe]

Sorry if I annoy anyone with this question, but I don't have the patience to delve into 27 pages.  What I am looking for is a cheap meter for some low resistance measurements.  I need to fairly reliably measure 15 and less than 1 on an FRU for a piece of deployed company equipment.  My cheap Velleman meter(with Brymen leads) does it but it is bigger than I want to carry in my toolbag and I would rather not pay $50 for a Fluke 101 if this meter will do what I need.  This isn't going to be a constant use meter but just for this specific field application.  I have better meters at home when I rebuild the FRU.  It won't even be used for V or A measurement of any kind, just the resistance measurements.  If anyone can test their AN-8008 and let me know, that would be awesome.  It's even cheap enough, if it works, to buy 2 in case I leave one behind on a service call and don't get it back and it would still be cheaper than a 101.

[bitseeker]

GreyWoolfe,

I asked a related question in the other Aneng thread last month and evava did some test measurements. They're not quite as low as you want to go, but look promising. Have a gander at https://www.eevblog.com/forum/testgear/new-aneng-multimeter/msg1276004/#msg1276004 to see if it might fit your needs.

[Mark Hennessy]

My AN8008 measures those sorts of resistances just as well as my Fluke 87V does. In fact, you have to put the 87V into hi-res mode to match the 10 milli-ohm resolution of the AN8008. The only downside of the AN8008 is no relative mode, so you have to account for the resistance of the test leads manually. And the 87V is a touch faster to auto-range, but for your use, you could always go for manual ranging.

Of the range of tests I just did, the two meters agreed within a couple of counts of each other. No complaints from me 

Oh, and the Fluke 101 is only 0.1 ohm resolution...

[GreyWoolfe]

GreyWoolfe,

I asked a related question in the other Aneng thread last month and evava did some test measurements. They're not quite as low as you want to go, but look promising. Have a gander at https://www.eevblog.com/forum/testgear/new-aneng-multimeter/msg1276004/#msg1276004 to see if it might fit your needs.

I see what you posted.  1 resistor measured .98 .  That is just what I need. 15-18 is good, 30 is bad, according to the service manual.  I think it will work just fine.  Mark, I don't believe relative mode is necessary for my use.  The Velleman doesn't have it and the measurements are very close between it and my GW Instek GDM 8251A.  The Velleman is manual ranging so no big deal to put the Aneng in manual mode.  The 30 second wait to stabilize is no big deal, I can turn it on and remove the FRU and by the time it's out, the meter will be good enough.  I will grab one and if I like it, I will grab another.  I have a couple more sets of the Brymen leads from Frankie coming, I will use those instead of what the meter comes with, which will also help.

[Crumble]

For this kind of measurements it might be advisable to clean (the metal of) your test probes with acetone and then with contact spray, I found low value resistances to become quite a lot more consistent. I have a bargraph meter too and you can definitely tell the difference (btw continuity on a fast meter is a good indicator of probe cleansiness too).

[Neytron]

Hi, I just bought both models an8008 and an8002 I think both are a good complement. Modify the an8008 eeprom to add the temperature measurement function.

Direction 0xAD = 0x13 and 0xBD = 0x15 to add the functions ° C and ° F respectively in the mV position.

Copy calibration data from an8002 to an8008, addresses from 0x0B to 0x0F

Both measure the same temperature now

[GreyWoolfe]

I ended up ordering 1 yesterday.  I will put it through it's paces when it gets here.  If it works as I need, I will order another one.  When it comes in, I will do a comparison test under the exact circumstances that I will use it with my other hand held DMMs and post my results.

[Mr. Scram]

Hi, I just bought both models an8008 and an8002 I think both are a good complement. Modify the an8008 eeprom to add the temperature measurement function.

Direction 0xAD = 0x13 and 0xBD = 0x15 to add the functions ° C and ° F respectively in the mV position.

Copy calibration data from an8002 to an8008, addresses from 0x0B to 0x0F

Both measure the same temperature now

How do you modify the AN8008 EEPROM? I've been searching in the thread, but all I've found so far is that you need a PICkit programmer. It'd be great to add a temperature option to it.

[stj]

no, any programmer that handles 24'series eeproms or an arduino board.

[Crumble]

[...] but all I've found so far is that you need a PICkit programmer. It'd be great to add a temperature option to it.

Where did you find that? As said, it is an EEPROM, and there are more suited programmers for that. I don't think a PICKit will work (but it might, the 'C' versions are EEPROM too).

[stj]

a pk2 may work with AVRdude software.
maybe.

[floobydust]

One way to reprogram the EEPROM seems to be using an SOIC-8 clip, around $2 on Ali.
Then holding the DMM IC in reset, so it does not drive the EEPROM lines. So you don't have to lift the data/clk pins.
Then use the use the programmer of your choice. Like Bus Pirate etc.

I use an Arduino with SPI 3.3V level-translator and bit-bang.

[plazma]

[...] but all I've found so far is that you need a PICkit programmer. It'd be great to add a temperature option to it.

Where did you find that? As said, it is an EEPROM, and there are more suited programmers for that. I don't think a PICKit will work (but it might, the 'C' versions are EEPROM too).

PicKit works. I used a modified clone.

[hughtmccullough]

I have just got to grips with the EEPROM programming and this may be of some help to someone else who is new to it.  I used the programmer based on the CH341A chip that is available from various Chinese sources.  I connected this to the AN8008 with one of those SOIC8 clips that comes with a ribbon cable and adapter board that plugs directly into the programmer ZIF socket.
These are the items I am talking about:
http://www.ebay.co.uk/itm/CH341A-24-25-Series-EEPROM-Flash-BIOS-USB-Programmer-SOIC8-Clip-On-Board-UK-/162557028178?epid=1390692406&hash=item25d9276752:g:vG8AAOSwCQZZCi3S
...but this is just an example that shows both together, not necessarily the best deal.
I followed the procedure given in the Russian thread mentioned several times in this thread in connection with the AN8008. I have attached (I think) the instructions to save you looking them up, along with an English translation of the words.  Between the two you can work it out.  They are actually for the ZT101/102 but the relevant bits are equally valid for the ZT109=AN8008.  They used the PICKIT2.  So, that's definitely an option.
I use Linux mostly and tried the software available for the CH341A but it didn't work very well.  So, I ended up having to use Windows software.  There is a description of what to do here:

There is also useful information here:
https://onetransistor.blogspot.com/2017/08/ch341a-mini-programmer-schematic.html
That's about it.  You can look through this thread to see what bytes to change for adding/changing functions.
It took me a while to get there.  I haven't invented anything new and these are just some of the more useful resources that I came across.  So, hopefully this might speed up the process for someone else who is new to this.

On a private off topic note to Plazma, did you see my questions in the "Pocket Multimeter Shootout! ANENG AN101 vs. Uni-T UT120C vs. Victor VC921" thread? Have you any comments?

[texaspyro]

Does anybody have the locations for the WP and RESET connections on the AN8008?

I have a couple of nice thermocouple calibrators.  They let you select a thermocouple type and will output a voltage the simulates what that thermocouple would output for any specified temperature.

[hughtmccullough]

They are in the attachments I just posted!

[ciccio]

I've received the AN8002 I've ordered some weeks ago, to pair with my AN8008.
Nice instrument, but:
It seems the manufacturer is having some problems with the front panel artwork (see attache photo):
The second switch position is labeled V (DC in white), Vac, Hz and % duty cycle (yellow), but pushing the SEL (yellow) button switches only between V dc and V ac.
To measure Hz and % duty cycle you must rotate the switch to the fifth position, again labeled Hz and %.
The funny thing is that the photos on the supplier's site (Banggood) and other sites show a correct panel.
I'll solve the problem with a little piece of masking tape...
I remember another post reporting the same problem, but I could not retrieve it.
A quick test showed that the meter worked as specified. I like it very much.
Another problem (but my big, heavy and more expensive Meterman 33XR has the same) is that a broken thermocouple will show ambient (or cold junction) temperarure, and not an overrange, as any industrial thermometer will do. A simple pull-up resistor could do the trick.

[Mark Hennessy]

Mine is the opposite - the artwork doesn't include Hz and % on the voltage position, but the yellow button does. Ideally, you and I should swap cases

I've heard reports of meters where the yellow button only toggles between DC and AC, but yours is the first AN8002 I've seen with Hz and % printing on the case.

From what I can tell, there's no way to predict which version you'll get. There's pros and cons of each - at least it's quicker to switch between AC and DC for you.

[ciccio]

In effect I do not pressed hard fo use the meter (it was bpught just for curiosity).
Before I'll decide to use masking tape, please PM me to organize the excange of the cases.
UK and Italian postages will be very cheap.
Best regards

[Mark Hennessy]

I was joking about the cases - given how cheap these meters are, it's hardly worth the effort of posting parts of them around

Thanks again for posting your pictures. It's interesting to see how these meters are evolving over time

Mark

[stj]

maybe the differences are controlled by the eeprom - the documentation on the eeprom content is not exactly complete.