Handheld meter robustness testing

[exe]

There's this:

I know about it, it's horrible (imho). There are reviews on youtube. But it is not even autoranging... Although, I can't name anything better for the price.

[joeqsmith]

I've had a few people ask me about the CEM DT-9989.   A member here was posting about their bad luck trying to buy one.  UNI-T has something as well but seems again that I have not seen anyone who thought it was useful.

I have a need from time to time for a small battery powered scope and ended up with a couple of old Fluke 97s.  These are basically a meter and scope combined.  They work alright for what they are but there are no parts available for them. 

[kalel]

The meter I linked above mentions 10 kHz, but can't even DSO138 work with faster signals? Okay, it's not a multimeter... but it is small, cheap, and can work on batteries (I guess). It didn't get too many shining reviews (at least the ones I've seen). Getting the unsoldered version is riskier, as it would be hard to be absolutely sure or prove that there wasn't an issue with soldering the kit together if something doesn't work.

[bitseeker]

Yeah, looks nice, but only 10kHz? Might as well get one of these:

For $21, DSO150, nice enclosure, assembled, 200kHz. Pair it with a nice, safe, DMM.

Or for $46, get a DSO-112A,  2 MHz, 5 Msps.

[totalnoob]

Thank you Joe, I will have to look into those.

Paul

[joeqsmith]

Yeah, looks nice, but only 10kHz? Might as well get one of these:

For $21, DSO150, nice enclosure, assembled, 200kHz. Pair it with a nice, safe, DMM.

Or for $46, get a DSO-112A,  2 MHz, 5 Msps.

I've seen a few of these used in videos.   They seem to require an external power source.  Maybe someone makes a case with a battery pack for it.  Then is still is a scope, not a multi-meter.   The UT81 was a bit faster.  When I  was looking for small scope, I thought about getting one but did not see anyone say it was a good investment. 

I started a thread on the old  Flukes.  They can't read current or temperature directly and there is no capacitance mode. 

https://www.eevblog.com/forum/testgear/old-philips-fluke-97/

[bitseeker]

Yeah, it was just in response to the comments that the ET201 is only 10kHz and rather inadequate as a DMM. So, if a single instrument isn't a deal-breaking requirement, for not much more money, one might be able to do better with separate handhelds for DMM and scope.

The DSO112A has a built-in rechargeable battery. I think I saw it in operation on Marco Reps channel. I'm not that keen on having a touch screen, but the device seemed to show wiggly lines OK.

Anyway, back to the combo handheld scopemeters.

[exe]

There is also Velleman WFS210 for 20 quids discussed in https://www.eevblog.com/forum/testgear/vellerman-wfs210-wireless-oscilloscope-for-only-20-!/ . It's a battery-powered portable wifi oscilloscope. Software seems to be crap, I haven't decided if I want it to buy or not.

For isolated measurements I use my MicSig TO1104, but 1) sometimes I forget to disconnect power 2) it's my main scope, I need one more isolated from it (preferably a tiny device as my bench is small). That's why I asked about options. Also, measurements on the scopes I've seen are imprecise. I mean, I know there is only 8bit ADC, but looks like I get even less steps, even with averaging (firmware issue?).

[joeqsmith]

CEM offers an AT-9996 automotive scope meter.  They also have the AT-9995 which  is a 4000 count.  Tach will work with 2-10 cylinder engines.  The dwell supports 2,5,6 & 8 cylinder engines.   

Mastech has a MS6230, 2000 count.

Someone did show the internals of the BM-319s with some sort of review.
https://www.eevblog.com/forum/testgear/brymen-bm319s-automotive-dmm-teardown-small-review-tme-supplier-feedback/

Of the ones I have seen, I am leaning towards the CEMs and the Brymen.   CEM does not appear to have the manuals available.   

[3db]

Joe
How would you feel about doing a tour of your lab and,or your Fluke calibrator ?

3DB
 

[joeqsmith]

Joe
How would you feel about doing a tour of your lab and,or your Fluke calibrator ?

3DB
 

I have a old Fluke 731B reference standard that I show in several videos.  Besides that, I am not sure what you are referring to.  Most of the equipment has been used in various videos.

I ended up picking up an automotive meter to play with.   Don't expect me to unbox it and talk about how great it is for an hour. 
https://youtu.be/q_89qoFMivg

[rsjsouza]

Joe, good tests - thanks for sharing. At first glance I could confuse it with a Hioki - it has a somewhat close appearance.

The display susceptibility to high voltage could be a coupling between the input terminals and the Holtek IC - they are physically close. As you mentioned, the fact the buttons still beep is revealing the main chipset is still going its merry way - further apart from the input terminals. 

The susceptibility to RF/interference is quite bad as well... I would expect automotive meters to be fully wrapped in shielding.

[joeqsmith]

Towards the very end, you may have noticed with nothing connected to the meter it would reset.   If you have worked on problems like this, you are aware it may have nothing to do with the inputs.   Maybe they will make a better version down the road. 

After seeing the BM235 reset, I am not sure about their automotive products.  In the manual they spec 3V/m.  That's nothing.   

[bitseeker]

Don't expect me to unbox it and talk about how great it is for an hour. 

Oh, thank goodness.

[bitseeker]

No worries. I knew you wouldn't suddenly change your style.

[Muttley Snickers]

This was an excellent video and a good reminder to people that these types of products can be susceptible to all kinds of external influences. As no real destructive tests were conducted you should probably box this one back up and either make a claim or send it back because it was not as described, If you don't then the seller will not get the message that this practice as well as the meter itself is completely out of order.   

Many thanks for your great efforts, it reminded me of how much I now miss my Suzuki, on a side note a mate came around once and saw that I had one and said "I didn't know you were into bikes", I replied "I'm not really, just hospitals and nurses".    

[xcube]

CEM offers an AT-9996 automotive scope meter.  They also have the AT-9995 which  is a 4000 count.  Tach will work with 2-10 cylinder engines.  The dwell supports 2,5,6 & 8 cylinder engines.   

....

Of the ones I have seen, I am leaning towards the CEMs and the Brymen.   CEM does not appear to have the manuals available.   

CEM AT-9995 :
Manual

There are some more from CEM

CEM AT-9955:
Manual

CEM AT-9906DIS:
Manual

Nice review on ALL-SUN EM135 Digital Automotive Meter, many thanks for this.

After seeing the BM235 reset, I am not sure about their automotive products.   

I have a quick look at the teardown picture form BM235, BM257 and BM319.
It seems to me that BM31x will based on BM25x and have a little more shielding when a BM235.
But only your tests will show if it is true.

[bitseeker]

Joe, that engine emulator is awesome!

[joeqsmith]

I suspect the RPM with the Brymens would be limited to 10K in this application.  The were very responsive as usual.   I ended up providing them the link to the video starting where I had the 869s on the jig.  They can at least watch their little meter reset.   lol.  I may get one but like the Fluke people have been pointing out.  Wonder if it would die like the 87V. 

Joe, that engine emulator is awesome!

Thanks.  These little projects are what makes electronics such a fun hobby. There is always so many things to learn.  People who are bored with electronics as a hobby must have a really limited skill set.

[tautech]

I suspect the RPM with the Brymens would be limited to 10K in this application. 

Which isn't of much use if you want to tune a chainsaw. <sigh>

There's not much decent available for high RPM engines other than a genuine Husky tacho, but the $$. 
http://www.baileysonline.com/Chainsaw-Parts/Repair-Tools/Tachometers-Ammeter/Husqvarna-502-71-14-01-OEM-Pulse-Engine-Tachometer-502711401.axd

Still, I guess they're are cheaper than these that we used 40 years ago: 
http://www.baileysonline.com/Chainsaw-Parts/Repair-Tools/Tachometers-Ammeter/Oregon-Wireless-Tachometer.axd

[joeqsmith]

Looks like they may not have read the datasheet.  I think the meter's susceptibility could be improved with some very minor changes.  If I can get it to survive some basic levels without a shield, I'll look into changing the front end.   

[tautech]

I suspect the RPM with the Brymens would be limited to 10K in this application. 

Which isn't of much use if you want to tune a chainsaw. <sigh>

There's not much decent available for high RPM engines other than a genuine Husky tacho, but the $$. 
http://www.baileysonline.com/Chainsaw-Parts/Repair-Tools/Tachometers-Ammeter/Husqvarna-502-71-14-01-OEM-Pulse-Engine-Tachometer-502711401.axd

Still, I guess they're are cheaper than these that we used 40 years ago: 
http://www.baileysonline.com/Chainsaw-Parts/Repair-Tools/Tachometers-Ammeter/Oregon-Wireless-Tachometer.axd

I shift around 10,500 and go through over 11,000 running 160MPH or so.   Not to say that chainsaws are not fun.  They most certainly are!!

Nice. We've chatted about drags some time back.

How long have you had the logging Joe ?
BTW, the column for Nitrous is blank.... WTF. 

[bitseeker]

People who are bored with electronics as a hobby must have a really limited skill set.

Yeah, same goes for those who say they're bored because they're retired. Having to work for a living is my limiting factor!

[joeqsmith]

We don't all reach for the foil to solve every EMI problem.   

https://youtu.be/uuaRUWcrZRk

[Crumble]

I may be a rare breed but I love working far too much to retire.  One day that may change.

I love that attitude. However, personally I find that when I'm not working I do tend to loose focus on what to do and how to do it and progress gets slower. I respect you for keeping on doing your thing and doing it thoroughly, keep it up!