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Author Topic: Handheld meter robustness testing  (Read 1149577 times)

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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2225 on: December 10, 2017, 03:59:06 pm »
...
The only thing the meter appears to have going for it is a cal certificate but he appears to lend far to much weight to that, eg. does the certificate still have any legal weight if the meter falls on the floor? I'm sure Joe could invalidate that certificate in seconds.

There is not much to validate or invalidate.  Every company will have different requirements and procedures.   Over my career,  there are often cases we will have equipment that is not calibrated.   Then there are cases where we calibrate more often.  It really depends but it's always documented.   Handheld meters do not cost near as much as some of the equipment we have under control.  I am not aware of one case where we have had a report generated for a handheld meter.  These are normally checked for cal on an annual basis so any included cert really means nothing beyond if we wanted to track the drift, which we would not do.  It's in or out.   If its out, it gets repaired and or aligned and calibrated.   

Offline Metermeister

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Re: Handheld meter electrical robustness testing.
« Reply #2226 on: December 10, 2017, 06:27:10 pm »
>>>>>Mostly the video is a waste of time, you won't learn anything by watching it, my opinion of Agilent meters was lowered by watching it.
>>>>>or anything about testing methodology (his video is in no way a rebuttal of joe's)

 i do not agree. 95% meter video reviews have no methodology as you say. They mostly unique and individual and that is okay.
No one claims expert on subject (at least very few). In my country electronics is highly priced so all information is gainful and any insight is good.
Please stop being negative as there is positive in all things. I have seen much worse and much better videos but that is not relevant.
I actual did learn by his video and becuase of it I buy this meter (now waiting for shipping) becuase it does what I need and this review help me choose so all things are unique to each person needs. It seem good price and quality. Even joes last video show this meter can handle lot of abuse and still be good. :horse:
 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2227 on: December 11, 2017, 05:43:02 am »
I've been thinking about upgrading my home temperature chamber (meat packing box) to include cooling.    I had a few old Peltiers from back in the mid 90s.  One is about 60mm square.  No idea on the brand, part number or specs.   Made up a heatsink to try it out.   With 10Wish, small sink reaches 12.7C and the large about 38 with the fans off.   At 50W and the large fan on, it reached -12 open air.   The handheld meters are not much of a load and I have no need to ramp it very quickly.  I'll see about mounting it the box and give it a try. 

Offline HalFET

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Re: Handheld meter electrical robustness testing.
« Reply #2228 on: December 11, 2017, 07:06:58 am »
You can pick up a temperature controller for PLCs of aliexpress quite easily.  ;D
 

Offline EEVblog

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Re: Handheld meter electrical robustness testing.
« Reply #2229 on: December 11, 2017, 12:56:43 pm »
I've been thinking about upgrading my home temperature chamber (meat packing box) to include cooling.    I had a few old Peltiers from back in the mid 90s.  One is about 60mm square.  No idea on the brand, part number or specs.   Made up a heatsink to try it out.   With 10Wish, small sink reaches 12.7C and the large about 38 with the fans off.   At 50W and the large fan on, it reached -12 open air.   The handheld meters are not much of a load and I have no need to ramp it very quickly.  I'll see about mounting it the box and give it a try.

My 50W Peltier chamber gets about 17-18degC below ambient, so maybe 6 degC at best in the lab
Could do with better insulation though, but it's already pretty decent.

 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2230 on: December 12, 2017, 01:51:14 am »
Not too bad.   I was thinking about a single stage desktop ice maker depending how my meat packing box works out. 

Cut out a section of Pyropel for a gasket and sealed it with silicone.   The packing box is roughly 60mm thick.  I cut a few channels for the air and will add insulation into this area.   With no load, the old heatsink resistors and fan are inside for some thermal mass but the secondary box removed to get some idea on ramp rates.  Slow, very slow.   

It seems to hold at zero with 30W.  input.   One sensor is near the center, the other in a lower corner.   The small fan does not do a great job but there is a lot of space in that box right not.  The largest thing I have ever put inside it was that Gossen meter so I plan to add more insulation.

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2231 on: December 13, 2017, 01:03:54 am »
Ramping the box from 22C to 5C then to -5C.  The X-axis is in seconds.  I have not tried to tune it as I plan to add more insulation. 

A)
Red is the temperature
Blue proportional term
Green intergral term
Yellow is the error

B)
Only showing the temperature

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2232 on: December 13, 2017, 01:38:09 am »
Cut up some of that foamed packing out of a shipping box for insulation.  This is a much better size for what I use the box for.   There is plenty of room for the Gossen to sit on it's side and still get air flow around it.   Making one more ramp with it now to see if it improves things.   Afraid with a large thermal mass like the Gossen, it won't help the ramp times but it should at least hit -5.

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2233 on: December 13, 2017, 03:32:01 am »
Ambient to -10C.   About 1 deg overshoot without tuning it.    Regulation is well within a tenth.   Time to see how low it will get. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2234 on: December 13, 2017, 03:59:42 am »
Almost -15C  but I doubt it would hit this in the summer with the same power fed into it and the only load it has it the fan.

Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #2235 on: December 13, 2017, 11:29:42 am »
Thanks for sharing your work, Joe. I suspect one of the good things of having such slow ramp is to avoid condensation. 
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2236 on: December 13, 2017, 04:42:58 pm »
I may need to add a drip pan. 

Ran some wires into the box along with a K type.  I stuck it inside of that low end automotive meter.   

I like both the Brymen 869s and UNI-T 181A two temperature inputs.  I use this fairly often on the 869s.  I don't have the cable for the Brymen so I though I would use the 181A to collect the data.  It seems to work except I can't seem to get it to plot both temperature inputs.   It at least seems to record them.   Of course the battery is low and it needs to be recharged because of it's non-standard battery and you can't charge it while you are using it.  Too bad, it could be a really nice meter.   

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2237 on: December 13, 2017, 09:50:02 pm »
Had some time to waste while the 181A is charging up,  so I went ahead and glued the insulation into the upper section.   The battery finally died on the Brymen as well.  I keep meaning to put a good battery in it but I keep damaging meters so there seems to be an endless supply of cheap batteries.   :-DD     Won't be much longer and we can give it a go, maybe another day and the battery should be charged.. 

Offline kcbrown

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Re: Handheld meter electrical robustness testing.
« Reply #2238 on: December 13, 2017, 11:20:42 pm »
Had some time to waste while the 181A is charging up,  so I went ahead and glued the insulation into the upper section.   The battery finally died on the Brymen as well.  I keep meaning to put a good battery in it but I keep damaging meters so there seems to be an endless supply of cheap batteries.   :-DD     

Yours is probably one of the few labs in which the batteries consistently outlive the meters they came with.   :-DD




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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2239 on: December 14, 2017, 12:56:57 am »
Starting out, the three sensors read well within 1 degree.  The one K-type sensor came with that last meter.   I set the 181A to log every second.   

I used LabView to plot the data rather than Excel.  5471 seconds or about an hour and a half.   The actual air temperature is faster.  Again, one TC is taped to the LCD and the other inside the meter.  Both will lag a bit.  This is also why the one stuck to the LCD does not dip below when it undershoots.   The meter is a fair amount of thermal mass.    Looks like the half degree delta in the two K types tracks flips but I was not very careful to make sure things had stabilized before starting. 

It could use an LED light and a camera for looking at things like meters. 

Offline bitseeker

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Re: Handheld meter electrical robustness testing.
« Reply #2240 on: December 14, 2017, 05:14:05 am »
Had some time to waste while the 181A is charging up,  so I went ahead and glued the insulation into the upper section.   The battery finally died on the Brymen as well.  I keep meaning to put a good battery in it but I keep damaging meters so there seems to be an endless supply of cheap batteries.   :-DD     

Yours is probably one of the few labs in which the batteries consistently outlive the meters they came with.   :-DD

 :-DD True. First I've heard of such a problem.
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Offline kcbrown

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Re: Handheld meter electrical robustness testing.
« Reply #2241 on: December 14, 2017, 05:42:06 am »
Had some time to waste while the 181A is charging up,  so I went ahead and glued the insulation into the upper section.   The battery finally died on the Brymen as well.  I keep meaning to put a good battery in it but I keep damaging meters so there seems to be an endless supply of cheap batteries.   :-DD     

Yours is probably one of the few labs in which the batteries consistently outlive the meters they came with.   :-DD

 :-DD True. First I've heard of such a problem.

I chalk it up to terrible luck, myself.  :-DD


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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2242 on: December 14, 2017, 03:05:34 pm »
I let the 181A charge all night and it finally finished.   It needs a thicker case with AAA cells.   

Looking at boroscopes.   Most claim they are waterproof and some have operating temperatures of 0 - 80C.  They also have the LEDs built in.  This may be the way to go when testing meters that can't log remotely.   I also added a USB3 extension cable to the mix.

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2243 on: December 15, 2017, 05:40:56 am »
I placed all three sensors next to each other and then cycled the packing box.  Basically I wanted to see how well the three sensors track before moving on.  This is the UT181A software showing the various ramping.   

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2244 on: December 15, 2017, 05:47:09 am »
What I've done here is taken the data from the 181A software along with the data I collected from the control program and overlaid them.  Both the 181A and the PC were collecting data at 1 second intervals.   The small spike in the 181A near 5 deg. C is from me wrapping the meter in a towel. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2245 on: December 15, 2017, 06:04:56 am »
I let the packing box settle at 60 C for a half hour to show the stability.  Again, there is no load in the chamber but I doubt a meter is going to present much of a load anyway.    I then drove it back down to 0 and again let it settle.  It's not as stable at the colder temperatures but more than good enough for what I plan to use it for.   

Now I just need to get a camera for inside and we can give it a try on that ALLOSUN or my UT90A meter.   It's getting to be colder here.  Maybe we can do some snow tests as well.

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2246 on: December 15, 2017, 08:30:24 pm »
Time to do some load testing with the meat packing box.   Most of what I have used this box for has been less than 1W.   Most the the meters I have looked at would not be much of a load as long as they were not measuring high currents.   Even then, 20A and a 0.01 ohm shunt is about it (with the UT61E I modified). 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2247 on: December 16, 2017, 01:06:17 am »
Red showing the temperature with various stepped loads. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2248 on: December 16, 2017, 01:23:35 am »
I started out at 5C, let the box stabilize, then applied a 2.4 Watt load and watched the response.  Next, I removed the load and let it settle.   I tried 14 Watts but the box just can't remove that much heat so I dropped it to 6.5 Watts.   Looking at the I term, this appears pretty close to the limit at this temperature. 

Next I took it to 50C and again let is stabilize.   I then added the 6.5 Watt load and waited for it to settle.  Then I applied 14 Watts.     

I then applied 23.6 Watts which was more than enough to heat the box without the peltier.  I have a window comparator that monitors the error and will change the polarity if the temperature exceeds 5 degrees.   At 55C, it switched and starts to cool.  There is some undershoot.  Then I remove the load and again at 45 it changes polarity and starts to heat and overshoots. 

Camera is next. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #2249 on: December 16, 2017, 07:42:09 pm »
Before getting my meat packing box, this was my thermal chamber.  Shown here in 2003 as I am sorting transistors for the antique Tektronix current probe.   I wrote RAP about repairing it and sent him pictures of the test fixture knowing he would have some good advice.   

Quote
"You could ask Fairchild if they sell the 2N3906 and 2N3906 chips in TO-18. I bet if the military wanted to buy 100 of these for $30 each, they could get them just fine,but, how much AUTHENTICITY do you want to pay for?

Best wishes. / rap"

The UT181A is now inside the container.  I've added the ability to run a profile.   I've looked at this meter in the past and it was the most stable out of the ones I have looked at.  Again, it could be a very nice meter with a few small changes.   


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