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

[stj]

any chance of the rest of the schematic?
i'm curious about the star on the resistor and the function of the jumper.

[crazyguy]

any chance of the rest of the schematic?
i'm curious about the star on the resistor and the function of the jumper.

RLD is the signal input pin, i.e. short the jumper in NCV measurement

I think the resistor value (10M) is not that critical. It just connect the antenna to the ground.

[barry14]

I received my AN8008 21 days after buying it on Ebay.  Shipped from China.  I paid $10.00 for it plus $4.34 for shipping, or a total of only $14.34.  For that price, it is a  remarkable meter.  I checked it on most ranges and functions and it easily meets its specifications, usually much better. It comes with 2 sets of test leads and a wide range of tip adapters. The built-in stand is flimsy but usable.

[floobydust]

NCV measurement from the AC voltage signal into the RLD IC, the measurement results show five grades, 0 ~ 50mV display EF, 50 ~ 100mV / 100 ~ 150mV / 150 ~ 200mV / 250mV or more to 4 show a '-' character (adjustable) and with(?) the rhythm buzzer sound.

Applications need to be adjusted according to the value of Rx and the induction line. NCV measurement and the minimum resolution that can be set E2 (In 0.1mV): 25h (H) & 24h (L) set in base NCV measurements, 27h (H) & 26h (L) NCV resolution setting,
Calculated as the measured value - in base) / = 0 ~ 4 Resolution (rounded result), the count is greater than 4. 4. Such as:
25h (H) & 24h (L) = 0064h, 27h (H) & 26h (L) = 0096h, measuring the induced signal = 50.0mV, then LEVEL = (50.0-10.0) /15.0~=2, the display section 2 '- -. "

Optional PT1.2 NCV function as a control indicator (E2 provided F9h.bit0 = 1). When no signal PT1.2 = 0, a letter.
When the number PT1.2 with buzzer output, buzzer PT1.2 = 1, and 0 otherwise. This setting has no effect on other functions, PT1.2 = 1.

[floobydust]

I spent time reverse-engineering and figured out the schematic but the IC (die) pinout a bit different than DTM0660. The actual MCU must be the same family but with better A/D resolution and external Vref.
My guess is Dream Tech International writes the firmware for the multimeter MCU.

From Russian AN8008_1715xxxxx EEPROM dump I can see unused functions- such as temperature measurement, hFE, middle current, non-contact AC voltage detection (NCV) etc.
Should be possible to enable some eggs.

I could not find a UART TX line. I think the die-bonding wire is not brought out 

[tronde]

GBP 8.99 including shipping. Wonder how much profit is left from that?

http://www.ebay.com/itm/AN8008-True-RMS-Digital-Multimeter-9999-Counts-Square-Wave-Voltage-Ammeter-AC-DC-/162596699062

[kalel]

GBP 8.99 including shipping. Wonder how much profit is left from that?

http://www.ebay.com/itm/AN8008-True-RMS-Digital-Multimeter-9999-Counts-Square-Wave-Voltage-Ammeter-AC-DC-/162596699062

Isn't that one possibly a fraud? Considering the price, not the seller.

[joseph nicholas]

GBP 8.99 including shipping. Wonder how much profit is left from that?

http://www.ebay.com/itm/AN8008-True-RMS-Digital-Multimeter-9999-Counts-Square-Wave-Voltage-Ammeter-AC-DC-/162596699062

This doesn't work with PayPal.

[tronde]

Have not bought myself, but I get a choice of paypal or creditcard at checkout when I try.  Isn't payment options handled by ebay? 

[hugatry]

Have not bought myself, but I get a choice of paypal or creditcard at checkout when I try.  Isn't payment options handled by ebay? 

After selecting PayPal as payment option and logging in, there was an error saying the payment option isn't available.
And now the product has been removed from seller's listings. Either the payments were disabled because of possibility of that listing being a fraud, or the item was removed earlier and it took a while until that got synchronized across the servers 

[MacMeter]

Sounds like a "deal breaker", at least now you can afford a sandwich!

[kripton2035]

Quote from: crazyguy on Yesterday at 19:15:29

>Quote from: stj on Yesterday at 18:46:34

any chance of the rest of the schematic?
i'm curious about the star on the resistor and the function of the jumper.

Here is the translated datasheet into english, with automated software help.

[floobydust]

I got better stability and accuracy after changing the big bypass cap.
I found 3VDC rail has ~30mVpp of noise, low freq. (1kHz) and high freq. from DMM IC charge-pump.

The PCB has places for four 22uF 1206 decoupling capacitors C10, C14, C15, C16 but what's populated is one through-hole 100uF 16V YXA electrolytic that has poor ESR.
Changed to 47uF+two of 22uF X7R 6.3V (total measures 84uF) and 1/3 the noise now. Readings are more consistent and repeatable. Before I always had 2-5 counts variation.

The ICL8069DCZQ 1.2Vref is pretty quiet, C11 0.1uF across it but datasheet gives 4.7uF so you could upsize.

[stj]

hardware mods - nice.

i need to check my 8002 board - it uses a YXA, maybe stuff a polymer cap in instead.

[Naguissa]

Ordered one on ebay from China. Almost 16€, but had a 15€ coupon for a 20€ order so I added a magnetic usb and paid less than 6€.

Let's see when arrives...

Enviado desde mi Jolla mediante Tapatalk

[plazma]

I wonder what the MOQ would be for a slightly customized AN8002 or AN8008. Bonded TX pin and remove the fake CAT markings.

[kalel]

There's another suspicious listing on eBay, I guess this model is becoming very popular?

[Kalvin]

Got my 2 today. Nice and small. Useful when one runs out of DMMs and still need to measure something.

[stj]

I wonder what the MOQ would be for a slightly customized AN8002 or AN8008. Bonded TX pin and remove the fake CAT markings.

i wouldnt call the CAT markings fake without checking the detail - the fuses dont count.

[b_force]

I got better stability and accuracy after changing the big bypass cap.
I found 3VDC rail has ~30mVpp of noise, low freq. (1kHz) and high freq. from DMM IC charge-pump.

The PCB has places for four 22uF 1206 decoupling capacitors C10, C14, C15, C16 but what's populated is one through-hole 100uF 16V YXA electrolytic that has poor ESR.
Changed to 47uF+two of 22uF X7R 6.3V (total measures 84uF) and 1/3 the noise now. Readings are more consistent and repeatable. Before I always had 2-5 counts variation.

The ICL8069DCZQ 1.2Vref is pretty quiet, C11 0.1uF across it but datasheet gives 4.7uF so you could upsize.

Nice job.
These are easy hacks that everyone can do and are very affordable

[Fungus]

i wouldnt call the CAT markings fake without checking the detail - the fuses dont count.

Sure they do. A meter with a CAT rating has to live or die safely at that rating with the selector switch in any position.

If the fuses are stamped "250V" then they can't possibly claim it's 1000V CAT rated. Simple as that.

[Fungus]

Got my 2 today. Nice and small. Useful when one runs out of DMMs and still need to measure something.

Still didn't get mine. 

[alm]

If the fuses are stamped "250V" then they can't possibly claim it's 1000V CAT rated. Simple as that.

Especially since that 250 V is likely only applicable to AC. A 1000 V rating requires the fuses to also work at 1000 VDC.

[Kalvin]

Quick test:

Took a 1.5V battery and measured the battery voltage with two AN8008 and one UT61E simultaneously: AN8008s displays 1.565 +/- 0.001 and UT61E 1.5655 +/- 0.0001.

Current measurement test with the three DMMs in series in uA range: 3.37 uA +/- 0.01 uA.

[stj]

fuses are only for reading current, the CAT ratings are only for reading voltage.

*and i'm pretty sure they dont cover the ability to do something stupid like spining the rotary switch while the leads are hot.