Products > Test Equipment
EEVBlog 121GW Multimeter Firmware Details
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Lion_Tamer:
I have just tested my meter on the capacitance mode to see what sort of drift it has with results as below:

Set-up = The meter was placed in front of me between my keyboard and 2 monitors, probes were plugged in and clipped in to the holder on the back with nothing else connected and the excess lead laying on the bench. Blue tooth and logging was turned off. I left the meter in auto range mode on capacitance mode. Test length was 30 minutes each time.

Test 1:
Firmware Version 1.51
Available Resolution 10nF
Starting value 0.00nF
End value 0.00nF
Comment: At no point in the test did I see the meter value change.

Test 2:
Firmware Version 1.57
Available Resolution 1nF
Starting value 0.000nF
End value 0.002nF
Comment: The meter drifted up to 1pF after about 5 minutes and 2pF after 10 minutes, at one point during the test I did see 3pF on the display but it only lasted a couple of minutes.

I also tried touching but not pressing the buttons and leads during both tests with no noticeable changes to the displayed value.

Meter Serial No:180701854

I may have to look and see if I have any low value caps to test with when I can get a chance to sort my workbench out after recent building work.

Jem
CDaniel:
For capacitance there is not a zero offset calibration in the manual , anyway with or without the leads connected is showing 0.000
Interesting ...
lowimpedance:
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Jan 8th 2019
EDIT : Just for clarity of my posts and further down in relation to the problem found with the capacitance measurement. 

Below was in response to a previous members post relating to a bug (as noted above, and yes this is not the correct thread for this stuff but anyway..).
A number of posts by another member were removed by them which generally makes the thread seem disjointed with my responses.
But as the detail of my posts are still of interest I will leave them here.
I did ask in the other thread when the discussion moved there to move the posts from here but that did not happen and that time window has long passed.

*********************************************************************************************************
Okay I updated my kickstarter meter (1st batch) to firmware 1.57. And tested some lowish value capacitors. All connected to the meter via short leads and croc. clips.
The Meter was in Auto ranging mode and gave quick measurements on the three capacitor values when connected.

first value
 100pF silver mica.
 Initial connection showed 0.100 nF +/- 1pF -2 pF. With no capacitor connected the meter reads 0.000 nF
Repeated disconnect and reconnect gave same result. Leaving the cap connected and then turning meter OFF then ON from the RH OFF position did not affect the measurement.
Now using the LH OFF position introduced errors into the measurement, which then also persisted when also using the RH OFF then back to ON. A 100 pF with a variable reading
around 30 pF (not consistent).  :-\
Also cycling through the modes on that switch position did not restore correct measurement.

 1 nF polystyrene
 Initial connection showed 0.990 nF
Repeated connection gave the same result. Leaving the cap connected and then turning meter OFF then ON from the RH and the LH OFF position did not affect the measurement.

10 nF silver mica (a L&N standard cap !)
 Initial connection showed 10.110 nF. Cycling through the modes back to capacitance again now gave a reading of 10.040 nF. (This value corresponded to my Fluke 87V after I REL the 0.26 nf Offset out  :P.)
Repeated connection gave the same result. Leaving the cap connected and then turning meter OFF then ON from the RH and the LH OFF position did not affect the measurement.

Last test was to 'pad' the input capacitance with the 1 nF and REL it out then connect the 100 pF and repeat that a number of times.
The measured value was 0.100 nF and was the same each time it was re connected.

No drift measurement done
*******************************************************

NOTE :When I went to the firmware download page I noted a message above the firmware list saying quote:
"NOTE: This version has a change that will not function correctly with the app in capacitance range. An update to the app will be released soon."

Its not clear if this refers to the current firmware on the list with the DMM and the logging app or just the capacitance mode on the meter itself  :-//.
Or this message has been there for many firmware revisions !, as I only just updated from 1.17 its been a while since I looked at the firmware page.
lowimpedance:
 Yeah , not sure what to make of the initial success with using the RH OFF only, as it generally went (and stayed) pear shaped after using the LH OFF.
Will try to repeat after the meter has been off for some time.
My testing was with a pair of DIY short leads so not much to twist so thats why I used the 1 nF  to get of the measurement 'floor' !. Seemed to give good results after the REL.
 I had quite a lot of issues directly attributable to the sloppy switch which I resolved with similar shimming before the official shim was released.
Still not convinced this switch design is issue free yet.


lowimpedance:
 Re test of 100 pF after more than an hour turned off. Result was a correct reading of 0.100 nF when connecting / remove and re connect to the croc. clips.
Next leaving connected and turning OFF/ON from both directions initially gave correct reading but a short time later the reading started to display approx 82 pF instead.
I then cycled through the modes on that switch position and then re measured the 100 pF with the result now down around 25 pF or so as previously tested.
So a sort of repeatable result.
 Noted that the larger capacitance measures start a bit higher as well and then drop a small amount and could correlate to the same amount observed with the 100 pF. Needs further testing.

At this stage I have no plans to remove the switch, which considering the amount of usage I have given it would probably not show to much wear.
They did appear to be quite clean at the time I had the switch out, (nice gold plating).
However I will keep this in mind for when I do feel motivated to get in there again
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