Poll

Are you interested in seeing more handheld meters tested?

This testing is pointless! Please STOP damaging these meters!
3 (6.4%)
 Yes, I would like to more meters tested.
44 (93.6%)

Total Members Voted: 47

Author Topic: Handheld meter robustness testing  (Read 648231 times)

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Offline joeqsmith

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Many of you are aware that TechnologyCatalyst or 5ky, purchased several handheld meters out of his own pocket in order to run another $50 shootout.    The thread may be found here:
https://www.eevblog.com/forum/testgear/new-$50-multimeter-shootout-15-dmms-compared/  His Youtube channel  may be found here:
https://www.youtube.com/channel/UCYVMnw_W7-Rq-yJk80vprug/videos

One of the things that was brought up was testing these meters with some sort of electrical transient.   5ky has graciously accepted my offer to run them however with a slight twist.   

After running the first set of meters and now knowing roughly how they fail and what sort of energy is needed, I plan to start over from scratch and build a new transient generator.   The reason for the new generator is simple.  It will be programmable and allow me to automate some of the testing.   This will allow me to repeat tests and hopefully not spend near the time.  The last time, the UNI-T came in late from China and was just throne  into the mix and was damaged beyond repair.   I never knew just how poor of a design it was compared with the other meters.   The same for the Fluke 87V.   It would have been nice to know just where it failed at.     

Don't expect to see and covers blowing off the meters.   New generator does not mean more energy and 20J does not do the same damage as a KJ.   Like before, I plan to keep things at levels just high enough to stress the meters input protection circuits.   So if you are looking for a lot of fire and exploding parts, look else where.   I will keep the old generator just in case one of 5ky's meters does so well I think it could pass that test.       

I purchased a new Brymen BM869s as my basic home meter (huge step up for me).   A few members have asked about how robust this meter is.   My plan is to put this meter along with the 101 into the batch.   

5ky and I have not yet spoke.  I have a lot of work to do before I will be ready.    I may do some quick videos as I start to make some progress. 

In the mean time, here is an old 80's article on surge testing to kick things off ....
http://pml.nist.gov/spd-anthology/files/Dont_kid-kill.pdf
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline 5ky

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No rush, the meters are all in a plastic tote awaiting your word  :-+
 

Offline joeqsmith

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Video describing the new transient generator and initial testing of the power stages.

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Thinking about the AC wall socket test Dave shows during some of his meter videos....

Originally I had a 2M resistor in series with the output that I injected a voltage on to see if the meter was working.   Often, I had an AC wavefrom (wall transformer) in series with a DC supply so I could check both AC and DC modes without changing the setup.

With this test jig, I was thinking to have some sort of higher power bias that could substitute for the AC wall socket test Dave shows.    I had thought about just using a transformer but I loose the DC.   In the last video, this is why I showed the rectified signal.     

I know when I was testing with my 1KV high voltage supply (good for about 1mA) it was not enough current to overcome the protection circuits in the meters.    This is why I tested using the antique Drake radio's plate supply.  This is good for 300mA average.   None of the meters I looked at presented enough load to make that supply droop.     

Can't see making an arbitrary generator that can supply KVs at 100's of mA just to stress some meters....   So leaning towards a fixed transformer with rectifier like I showed.


 :blah: :blah: :blah:
For those crappy meters that actually get damaged when connected to the 220 line,  how much current was actually required to get them to fail?   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Have the Teflon spacers installed now and finally put a probe on it.   5.5KV pulse from new generator into an open.    110us FWHH can be set shorter.     Seemed to work fine down to 600 volts.   Very repeatable.   Ran into a couple of snags.  Noticed the new Brymen BM869s can't check the high voltage diodes I am using.   Is 14 volts drop too much to ask?  :-DD   The other problem is the relay I am using to trigger the generator welded the contacts after maybe 100 cycles.     Some good progress.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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Relay problem is solved.  Also after damaging the voltage sense, added protection for the amplifier.   Output stage now seems bullet proof.

I now have several damaged 25W bulbs.  This may not seem like a big deal, but while the voltage is lower than the old generator, it will put out roughly the same energy.  More than double what I damaged every meter I tested, except for that Fluke 101.    It will be very interesting to see how this new batch holds up..... 

Made up the test cable for it.   Attached picture compares new one with the original and how it fits to the Brymen.    Want to make sure that we get all that energy into the meter.....

Have a small isolation transformer on order now.   Because I have never actually seen a meter fail this outlet test,  I plan to design the system to handle
500mA.   Plan to rectify the AC to get my DC and AC bias when running the transient tests.  Will have a way to turn off this supply. 

The last major part is the controller for it.  Watching Dave's last video on the old Fluke, I was thinking to use an MC6801.   Another option I am thinking about is to run the thing headless and just use a PC with Labview.     
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online Vgkid

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Looking firward to more tests.
 :-BROKE  :bullshit:  >:D
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Online Fungus

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The last major part is the controller for it.  Watching Dave's last video on the old Fluke, I was thinking to use an MC6801.   Another option I am thinking about is to run the thing headless and just use a PC with Labview.   

Not sure what you mean by "use an MC6801" - build your own microcontroller?

These days almost everything is done with Arduinos.
 

Offline joeqsmith

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The last major part is the controller for it.  Watching Dave's last video on the old Fluke, I was thinking to use an MC6801.   Another option I am thinking about is to run the thing headless and just use a PC with Labview.   

Not sure what you mean by "use an MC6801" - build your own microcontroller?

These days almost everything is done with Arduinos.

The Fluke used an old Hitachi 63xx.   They had an OTP 6301 for a while.  I think there was a lawsuit over it.   Being a bit of a nostalgic buff, it may be fun to wire wrap one last board.   Maybe put a GAL on there.  :-DD   

The 6801 is a microcontroller.  No USB, CAN, Ethernet, FLASH, ADC, DAC, EEPROM.....     Does have some digital ports, serial port and PWM.    :-DD    There was talk of contest using a 1K device.   Maybe this will be my entry.   :-DD
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Made some progress on the new generator.   I cut and squared the parts to make the case.   These are 1/4 inch thick plate aluminum (in case she blows up!!).   I'll machine the front and back once I sort out the controller for it.    The Brymen does not appear all that concerned yet.....
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Unopened tube of Motorola MC68701CLs with quality guaranteed by Cristine.   



How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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The original Motorola parts were typically masked at the factory.   Hitachi came out with their clone which was CMOS and they had an OTP version. 

Second picture shows my homemade programmer  for the Motorola parts.   This was the 3rd programmer I had made.   Basically is emulates a SEEQ 2816AH device.  Has a dual ported Cypress part and a Lattice GAL for the logic.   Put you 68701 in the socket and hit the switch.   LCD

The transient generator does not need too many features.  Maybe a handful of switch inputs, couple of 8-bit ADC channels,  a few digital outputs a DAC and an LCD.   Maybe a little EEPROM to store some settings.   Nothing the most basic of PIC parts would have.    This transient generator needs something a little more classic....  :-DD

Time to see if the tools will still run.... 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Dang tools will run without DOSBOX.   

Hunting in my box of old displays, most are 16X2.  The largest one I had was damaged.   The one in the back I think is an old plasma unit.   I remember these looked pretty nice but it's way too large.    When the unit is running, I would like to have everything displayed on a single menu.   Getting it all to fit in 32 characters is going to be very cryptic.     Modern technology has spoiled me....

More searching in the junk pile and I uncovered an old Noritake VFD which will be perfect for this project.

Time to wire up something.       

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Once I tried to talk to some hardware, Windows helped me out.     :--   Then DOSBOX saved the day.   :-+   

I now have a 6801 talking with the display so I went ahead and ordered the push buttons.    All the hardware is now on order to finish it.   It's starting to come together but still thinking about 2-3 weeks out before I will try it out on a meter....       
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline 5ky

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I love me some dosbox.   :-+

I'm digging the retro components.  This is going to be a slick build!
 

Offline joeqsmith

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Spent the day working some more on the wire wrapping and relearning the 6801 instruction set.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline Lightages

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I am impressed. I haven't touched wire wrap since 1985?
 

Online tautech

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Spent the day working some more on the wire wrapping and relearning the 6801 instruction set.


Nice rats nest.  :-+
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Offline Muttley Snickers

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I wasn't sure as to the best place to leave these pictures so I will just plonk them here for now, found the listing on ebay au and this meter does have something about it that appeals, the overall look seems familiar and possibly the enhanced safety aspect after all if you cant plug in your probes then it's about as safe as it gets.

On the other hand if people that are unfamiliar with multimeter operations and procedures are in some way guided by the input jack shield as to the correct placement of the leads and that shield fails to work as intended as seen in the picture then they are better off without it.

« Last Edit: September 13, 2015, 02:41:06 am by Muttley Snickers »
 

Offline joeqsmith

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Sold my Ziftel (??) Slit wrap gun many years ago.   Would have made this job easier.    I think the wire wrapping is done as long as I don't add any more features.   :-DD    The basic software is now all in place and I have checked the hardware out.     

The biggest problem I see is that my basic code now takes up 2263 bytes and the MC68701CL only has 2048.   I would guess it's about 80% done and I was thinking to add a current probe with some sort of auto shutdown as well.   It's going to be tight!

Shown reading the high voltage input along with my very safe Weston meter and 500A shunt.





How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Recessed the front cover to give it a bezel look.   Drilled and tapped the holes so I could assemble it and start thinking about how I want to start mounting parts inside once they all get here.   Its a fair bit larger than the original generator and is going to be fairly packed. 


   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline 5ky

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That's going to be quite a bit larger than your old rig.  Did you make that new case?
 

Offline joeqsmith

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That's going to be quite a bit larger than your old rig.  Did you make that new case?

I looked into buying a case but yes, I am making the case for it from scratch.  The rest of the parts should be here tomorrow.   I hope to have the whole system assembled next weekend.   Then it's just finishing the code for it, make the cover for the case and figure out how I am going to letter it. 

Won't be much longer.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Remember ISP Expert and CUPL?   I am turning the hands of time back further to PALASM.   :scared:   Now where is that tube of 22V10's.....

I wound the current sense and tried it out.  Looks pretty good.   Not sure if is going to do anything to help the testing.  Hard to believe a meter would actually fail in ohms mode (or any mode) when stuck across the mains.  We will see. 

I have been working on the code and am now very close with 27 bytes left over.  2K will force you to have to think.   I just need to get the logic in there to run the tests and then start debugging. 

To top it off, the last of the parts arrived today.   The little step-up transformer looks pretty good.   I'll make a second video once I get things mounted in the case.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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PALASM sort of works in a DOSBOX.  The menus seem to screw up but it will compile.    Found a tube of PALs and one GAL.   Was able to get the old parallel port programmer working under Windows.   All that for a few FFs.  One more thing done.   




How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 


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