Products > Test Equipment

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

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psycho0815:
Not sure if anyone cares but fyi i just received a Tougs M103 from amazon germany, from a german seller for 23€ delivered and it appears to be the exact same meter. Just in case you live in the eu and don't wan't to go through all the china hassle.

plazma:

--- Quote from: psycho0815 on August 01, 2017, 05:00:31 pm ---Not sure if anyone cares but fyi i just received a Tougs M103 from amazon germany, from a german seller for 23€ delivered and it appears to be the exact same meter. Just in case you live in the eu and don't wan't to go through all the china hassle.

--- End quote ---
With a black case. Nice :)

Fungus:
My meter finally turned up. 31 days after purchase.

MacMeter:
I ordered one on Amazon, knowing it would be slow from China. But this was a 1st for me, kind of a time buying scam, I assume they lied about it being in stock. I'm pasting the sellers response when after tracking the package from China, I received a tiny envelope with a "free" shrink wrap sleeve for a remote control, worth about 10 cents. Along with a business card saying the real package would still be coming. I then put in for a refund, and Amazon lets the seller contact me via email. See if this response is logical!

"We sent it out on Jul 17, 2017, normally it would take 10-25 workdays from China to US,
As the item is electric product,  it would take more days to complete the customs clearance.
we are afraid it could cause a delay, so a free case for remote controls goes to you first and the real package is after. Normally you can receive the item you oredered within 12 working days, would you please wait for it?"

So I then said, just give me a tracking number for the REAL meter, a few days later, they send it, only shows as "label created". So I'm assuming the meter was NOT in stock, so they send something to buy time, and then ship it when it's in stock.

Just thought I'd share this odd story, another reason I mostly avoid buying directly from China. Hopefully, in another 2-3 weeks it will arrive.

floobydust:

--- Quote from: evava on July 29, 2017, 07:20:22 am ---I wonder if that 8uV gap around zero (meter doesnt show values +-1uV +-2uV +-3uV +-4uV, instead of it only shows 0 or +-5uV or more) could be eliminated or at least reduced?
Is that set in EEPROM, or is it invariably written in firmware?
Is it possible to find out?

Otherwise it seems to be stable enough, I see no need to hide these small values (+-1uV +-2uV +-3uV +-4uV).

--- End quote ---

I see that deadband on the uV range centered around zero. Readings start at ±5uV up. Input from -4 to +4uV reads zero.
This would be done in firmware to mask noise.  With this meter, to read uV that low, I think a preamp is needed.  In other words, AN8008 gives 1uV resolution at 4uV up.
DMM's don't have specs for their reading deadbands and hysteresis.

The other "stickiness" people are seeing in readings I think are due to the averaging and filtering of A/D readings done by firmware - within the product spec of  ±3 counts.
This got better after I did the capacitor mods on Vss and Vref to lower H/W noise.

Other uV effects are thermocouple EMF with test leads and probably AC hum and noise.

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