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

[ceut]

Hello,
I has been a long time since I have been here 

So I've bought an AN8008 (15€) and 2x UT210E (2x 24€) from banggood (which I like very much).
I've received my AN8008 yesterday and I have a calibration problem with it on the V DC (about 0.1V over).
I have tried with the calibration process without success: it's impossible to have something stable from a 500mV source.
So I have extract my 24C02A with my CH341A and only 3 wires, and I have put some jumpers to switch between program mode(CH341A) and read mode(DM1106EN mode), it works very well:




I have changed some options like adding Temperature in °C (only),  changing backlight time and power saving time, and it seems that calibrate with changing manually values works, but a little long to do.

I would like to disable annoying beep sound when changing mode, and slow down a little the display refresh because it seems that it updates too fast and then slowly stabilize the mesured value.

Also I find that the buzzer has a fixed delay which is too long and slow down the bip-mode + add some lag; I can't find if this delay is created by a capacitor or by the DM1106EN  (EEPROM?)

And I don't understand why there is a 9.99MOhms limit (whereas the AN8002 has 60MOhms), so I can't check my other DMM input impendance with this one 

Last thing is about the mA mode, why it lacks a range ?

I will continue to follow this topic, thanks for all informations in it !   

Hoping that someone will post the DM1106 datasheet in english 

[stj]

i see eneloops - did you try alkaline batteries?
i dont think the meter works properly at 2.4v

[ceut]

i see eneloops - did you try alkaline batteries?
i dont think the meter works properly at 2.4v

Hello,
Yes, after unboxing, I have put 2 fresh alkaline batteries and I have had this little calibration problem on V-DC.
Since, I use Eneloop to do the testing and flashing of the 24C02A, and I have the same calibration problem.
I try to correct this by changing values on the 22&23H adresses: it works but not easy.

Edit: After many mod tries on the 22&23 adresses, I have a good calibration now on VDC (my actual values are 22H= FF 23H=80 , original values were 8D and 81 so a little too high in mesurement).

[mnementh]

I couldn't help m'self... I had to get myself a shiny red spaghetti meter [...] I picked the "No Rush" option and got $5 to spend in Amazon Pantry... probably get me some BBQ spices or somesuch.

Spaghetti meter, but no pasta? No spaghetti sauce? Missed opportunity.

*Puts on best deadpan* They don't carry my brand. 


mnem
I put BBQ spices in my spaghetti. Doesn't everybody?

[rdl]

I'm running mine on a couple of older Energizer NiMH batteries (non-eneloop type). Every measurement comparison I made to my Fluke 87-III was spot on. It wasn't exhaustive testing, just spot checks here and there, but it does seem to work okay with that type of battery.

[ocw]

I received a Ragu 17B+ multimeter today.  I see that Amazon raised its price to $11.99 while it is going for around $15 from several American eBay sources.

While its specifications reminded me of the AN8008, the 17B+ is about the regular multimeter size rather than the small size of the AN8008.  Naturally, its circuit board looks entirely different (see the attachment).  They would have a hard time putting that 10 amp fuse inside of the AN8008.  The added relative/zeroing and MAX/MIN buttons are nice.  But its disappointing to have the 1 microvolt digit missing compared to the AN8008.

The DC voltage accuracy (about 0.1% high) came close to the matching my AN8008.  The Ragu's AC voltage readings were about 0.12% high and it maintained 1% accuracy or better from 8 to 1600 Hz.  It was 1 dB down at 2240 Hz (-3 dB at 3050 Hz).  The 17+ properly measured the RMS voltage of a square wave signal.  It measured frequency up to 54 MHz with a 1 volt RF input.  200 mV and less was adequate at lower frequencies.  It displayed 54.00 MHz with a much more precise frequency input.

The resistance measurement was very precise (close to 0.00%) near 1.XXX, 10.XX and 100.X readings. Between those points the readings were typically 0.10 - 0.15% high.  The only thing not fitting that description was my 10M 0.01% resistor being read as 10.04M (+0.04%).  The resistor test voltage was 1.00 volts while the diode check voltage was 3.28 volts.  The continuity alarm sounded with resistances below 50 ohms.

The uA DC current readings were about 0.1% low, the mA readings were around 0.3% high, and the A DC readings were about 0.15% low.  The three shunt resistances were 100.385, 1.4962 and 0.03253 ohms respectively.  Due to those resistances, the real world accuracy reading current of a regulated voltage without paying attention to those resistances was up to 1.1% low for uA readings and 9.2% low for mA readings.  I have yet to test the AC current accuracy, but I would expect it to be similar.

I'm not sure what happened to the capacitance measurement calibration.  It was as if the meter was zeroed with a negative 73 pF capacitor connected.  If you add that amount to all of the readings, it has pretty good accuracy.  Without that correction its accuracy is pretty bad until that amount of capacitance is insignificant.  The zeroing button didn't function in the capacitance mode.

The non-contact voltage detector set off its alarm when its display end was 2.5"/6.3cm away from a 120 VAC wire.

It's a nice meter and doesn't have the missing current ranges like the AN8008 does.  But, it doesn't have the ANENG's nice small size.  It will be useful for some tasks.

[mnementh]

My AN8008 arrived today; it spent the last week being bounced around several Post Offices due to the confusion and delay caused by Harvey. I'm with the other posters here; that extra lead kit is almost worth the cost of the meter. While quality of the fittings isn't the greatest, I'm pretty certain I can make them all quite reliable with a little careful resoldering. The assortment of end fittings does just SCREAM useful.

ocw, thanks for the quick Tech Teardown of the Spaghetti Meter... I was beginning to have second thoughts; after spending my $10 in my mind it was beginning to feel more and more like actually spending money for another of the Horror Fraught "Little Red Boxes"...


Cheers,


mnem
This space for rent.

[kalel]

Nice big fuse on that Ragu. I guess it compares with AN860B+? But the fuse seems better. At least looks the part.

[Fungus]

Nice big fuse on that Ragu. I guess it compares with AN860B+? But the fuse seems better. At least looks the part.

Looks impressive, yes, but notice that the fuse is only rated for 380V yet the meter claims "MAX 1000V DC" and "CAT IV 600V" on the front. 

I'm also not sure about the track spacing around it. Would it have killed them to bring this track down at a slightly different angle to gain a couple of mm more gap? There's plenty of space on the PCB! To me it looks as if that fuse might as well not be there if the voltage goes up high enough, it could simply arc across from the base of the fuse to that track.

Just looking at the picture I'd I'd say it's more like CAT II 300V than CAT IV 600V, CATIII 300V at best.

[kalel]

Nice big fuse on that Ragu. I guess it compares with AN860B+? But the fuse seems better. At least looks the part.

Looks impressive, yes, but notice that the fuse is only rated for 380V yet the meter claims "MAX 1000V DC" and "CATIV 600V" on the front. 

I'm also not sure about the track spacing around it. Would if have killed them to bring this track down at a slightly different angle to gain a couple of mm extra?

Still, if everything else was the same as an860b+, and it cost 10-12 USD, a great deal (a shame it's not int with free shipping). It would be interesting to see a comparison.

[joeqsmith]

I received a Ragu 17B+ multimeter today.  I see that Amazon raised its price to $11.99 while it is going for around $15 from several American eBay sources.

....

It's a nice meter and doesn't have the missing current ranges like the AN8008 does.  But, it doesn't have the ANENG's nice small size.  It will be useful for some tasks.

Larger fuses but looks like the same basic problem with the input.  I would be more concerned with mA fuse arch to return.  In your picture, it looks like the input it directly tied to common.   

[Fungus]

Still, if everything else was the same as an860b+, and it cost 10-12 USD, a great deal

No argument there. The $20 multimeter market is on fire right now (figuratively).

The Ragu  does look a slightly better bet than the 860B+ for the sort of people who want to poke at household mains. $15 more will get you a Fluke 101 though*, so... 

(a shame it's not int with free shipping). It would be interesting to see a comparison.

I only see USA/UK sellers selling them so shipping costs will double the price. I don't think I could get one for under $27.

Plus I really don't think I need another meter right now.

(*) $27+$15 = a Fluke 101 delivered to your door.

[ocw]

I forgot to mention, the Ragu 17B+ display is 6200 count in the voltage, current and resistance modes.  In the capacitance mode it is 10000 count as shown by  a 9.982 nF reading that I obtained.

[Mark Hennessy]

I forgot to mention, the Ragu 17B+ display is 6200 count in the voltage, current and resistance modes.  In the capacitance mode it is 10000 count as shown by  a 9.982 nF reading that I obtained.

Exactly the same as the AN8002/AN860B+

Everything screams DTM0660/DM1106EN chipset except one detail - the HF performance on AC volts. On every DTM0660/DM1106EN meter I've tested so far, the -3dB point is 3kHz. But this one is only 1dB down at 2.6kHz?

[ModemHead]

The Ragu sauce/measure unit is now up to $14.99 at amazon this morning.

[Fungus]

The Ragu sauce/measure unit is now up to $14.99 at amazon this morning.

The cheap ones seem to have gone from eBay, too. With shipping there's no way I could get one for less than about $50 now.

Three times the cost of the meter this thread is supposed to be discussing and more than a Fluke 101? No thanks.

[stj]

it would be interesting if they used the 1106 chip,
someone should bump it to 10,000 count in the eeprom and then see if the AC true-rms readings still look o.k.

[ocw]

On every DTM0660/DM1106EN meter I've tested so far, the -3dB point is 3kHz. But this one is only 1dB down at 2.6kHz?

I double checked that.  The Ragu 17B+ -1% voltage figure again was 1.6 kHz.  However the -1dB figure was 2.24 kHz this time.  I repeated the process several times--2.24 kHz is the correct figure.  I will correct my other message.  The voltage measurement was -3dB at 3.05 kHz.

I completed my accuracy verification of the 17B by measuring its AC current accuracy.  The uA AC readings were +/-0.1% while the mA readings were around +0.6%.  The A readings were about -0.3%. 

Similar to my voltage accuracy tests, I tested the current at 1X, 2X, 4X, 6X, 10X, 20X, 40X, 60X... points.  I precisely measure the output voltage of my audio generator and set the current by the proper choice of a 0.01% current limiting resistor.  This simulates the way that I most frequently use to meter to measure current--measuring the current from a voltage regulated power supply.  I mathematically correct that reading to see if it then matches the manufacturers specifications.  But, more importantly is how accurate the meter is without correction.  I feel that at least the moderate and higher price meters should not use an outdated VOM current measurement accuracy standard. 

For higher current evaluations I measure the voltage drop across four terminal precision resistors to determine the current being measured.  I make the tests at 60 Hz.  The current measurements most frequently have frequency response similar to that for voltage measurements.

[floobydust]

What's weird is how the factory CAL is done. You'd think it was automated.
But I can't see any calibration/test points on PCB, other than a soldered 0805 CAL jumper.
No serial data in/out. So not sure how data is being written to the EEPROM.

For the capacitance (null) calibration, it is funny the EEPROMs copy the "Uni-T" or "Brymen" number and use that for the stray capacitance value. Nobody seems to actually come up with the real value, only copying it.

This is what I have on the capacitance CAL:

Capacitance correction (500.0nF, 50.00uF)
The measurement function of the calibration table switch is placed in the capacitor position (or the resistance level (J1A, J1B short circuit)).

Calibrator output 500.0nF, wait for the display is stable, press +/- to adjust to 500.0 nF;
Can be used for the correction of the output value: 200nF ~ 600nF (100nF integer times), the recommended value of 500.0nF.

Calibrator output 50.00uF, wait for the display is stable, press +/- to adjust the display to 50.00 uF. If it has been adjusted, Press SELECT to skip this adjustment.
The capacitance value that can be used for correction: 20uF to 60uF (10uF integer multiple), the recommended value is 50.00uF.
Note: The capacitor needs to adjust the above two points, directly output the corresponding range capacitor value, the program will automatically switch the range. "
----------------------------------

Note there is an 6/9V ACV high-frequency correction factor in EEPROM at 28H, 29H

[Fungus]

No serial data in/out. So not sure how data is being written to the EEPROM.

The same way it's read out on power-up...

[floobydust]

I meant the DMM MCU external serial data in/out, as I thought that the MCU firmware does a bulk write to EEPROM.

The EEPROM SPI port cannot be shared with the DMM IC, you get bus contention if you try to communicate with the EEPROM, unless the DMM IC is held in RESET.

[ocw]

I found similar capacitor test frequencies on the Ragu 17B+ and the ANENG AN8008:

17B+      auto-selection of 0.58 Hz - 29.4 kHz
AN8008  auto-selection of 0.59 Hz - 27.5 kHz

Installing the 9 volt battery is confusing on the 17B+.  I didn't see anything on which way to install it.  The battery positive terminal goes to the left (the MAX/MIN button side).

[MacMeter]

I received a Ragu 17B+ multimeter today.  I see that Amazon raised its price to $11.99 while it is going for around $15 from several American eBay sources.

....

It's a nice meter and doesn't have the missing current ranges like the AN8008 does.  But, it doesn't have the ANENG's nice small size.  It will be useful for some tasks.

Larger fuses but looks like the same basic problem with the input.  I would be more concerned with mA fuse arch to return.  In your picture, it looks like the input it directly tied to common.   

I bought the Ragu, mostly because it was only $10, and I can just leave it on the work truck, and when I make a battery eliminator for it, I can leave it on in FREQ mode to monitor the 1800a mobile tractor generator. Useful sometimes having a meter you don't care about as long as does the job.

While I will never use it for current readings, would it still be wise if "possible" to put one of my spare BM235 fuses in there?

[MacMeter]

I found similar capacitor test frequencies on the Ragu 17B+ and the ANENG AN8008:

17B+      auto-selection of 0.58 Hz - 29.4 kHz
AN8008  auto-selection of 0.59 Hz - 27.5 kHz

Installing the 9 volt battery is confusing on the 17B+.  I didn't see anything on which way to install it.  The battery positive terminal goes to the left (the MAX/MIN button side).

I had to look closely deep inside with a flashlight to see the tiny mold marks for battery orientation. Then used a silver sharpie to make a legible mark. On mine the "Select" button does not seem to function as expected in some modes. If you to turn off the "Auto 15 minute shutdown" you have to hold the select button down before turning the meter on. In "Hz" mode further up the dial, the select button did nothing, but clicking on the Hz button itself cycled through the options. I suspect there are other user interface issues that were not fully tested before this was released, but for $10, I didn't have high expectations to begin with.

[stj]

I meant the DMM MCU external serial data in/out, as I thought that the MCU firmware does a bulk write to EEPROM.

The EEPROM SPI port cannot be shared with the DMM IC, you get bus contention if you try to communicate with the EEPROM, unless the DMM IC is held in RESET.

the meters i'v looked at have programming pads for the mcu, it's possible they have a passthrough mode, or a generic table they write to a blank eeprom.