Author Topic: EEVblog #1007 - Is a $25 Multimeter Any Good  (Read 111602 times)

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Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #275 on: July 20, 2017, 08:55:51 pm »
Qualified personnel (electrician+PPE) could make measurements on a live panel, but dangerous depending on the voltage class. It's frowned upon

If you're wearing a hard hat and carrying a large yellow multimeter they might let you.

If you're wearing a baseball cap and carrying a neon screwdriver? Not so much.

Still, this was apparently taken in Russia so different standards apply. Want to take some pictures of the pretty wires and switches? Just give the guy with the keys some American cigarettes and a bottle of vodka.

I don't think body-capacitance is enough for a neon-lamp that bright, 600VAC 60Hz 100pF I get Xc=26MEG and 19uA.

Maybe $0.001 Chinese safety resistor was failing.

(and he was this >.< close to disappearing in a big blue flash)
 

Offline Someone

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #276 on: July 21, 2017, 01:07:17 am »
That's a ridiculous photo!

No employer would allow you to even open the door on an energized panel, let alone no PPE like eye protection, gloves.
Then there's the $1 electrical tester with no return wire? How does it glow? From the dumbness lol  :palm:
Photoshopped busbars?

Just out of curiosity, how would someone troubleshoot a panel like that if they're not allowed to open the door with it energized? Do they just have to dismantle the whole thing and bench test each component separately? Or maybe turn it off, hook up test gear, instrumentation, etc, then turn it back on and monitor from a distance?
Both of your suggestions are correct and ways that industrial electricians might debug such a panel, but there are also cases where they might measure or even work on it live. The work would be carefully planned by a group of people and not just opening it up then investigating ideas as they come up, then it would be done with 2-3 people present who are all suitably trained in electrical safety and first aid procedures.
 

Offline Brumby

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #277 on: July 21, 2017, 01:28:01 am »
I did notice he kept his fingers as far back as possible.  Well away from the shaft and tip.

That has to count for something.
 

Offline joeqsmith

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #278 on: July 21, 2017, 01:37:02 am »
Tell you what: I'll up my bet to the price of a meter. If anybody thinks an AN8008 won't survive the grill igniter I'll get a meter shipped to joe and you can send me the purchase price via paypal if it lives.
I appreciate the gesture.
It's on it's way. Maybe in a few weeks I can run it. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline amspire

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #279 on: July 21, 2017, 01:54:14 am »
I don't think body-capacitance is enough for a neon-lamp that bright, 600VAC 60Hz 100pF I get Xc=26MEG and 19uA.
The glow is visible with just microamps of current. 19uA would be fairly bright. The voltage drop across the neon is something like 70V.

Someone probably did a bit of photoshopping in the photo to make it brighter.

Just did a test with one of these screwdrivers. At 240V AC 50Hz, the glow is very visible with 13uA. According to my calculations, my body must have been at about 160V AC and my body capacitance must be about 260pF!

« Last Edit: July 21, 2017, 02:10:51 am by amspire »
 

Offline jonovid

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #280 on: July 21, 2017, 02:01:50 am »
I have ordered it online, on the understanding that the AN8008 DMM is basic. but has some redeeming qualities for a hobbyist
working with low voltages like battery powered toys. grill igniters are not on the list.  ::)  also its not my only DMM on the bench.  reminds me, did Dave fix that piezo mosquito problem he had in his own branded DMM.
Hobbyist with a basic knowledge of electronics
 

Offline joeqsmith

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #281 on: July 21, 2017, 03:53:11 am »
I have ordered it online, on the understanding that the AN8008 DMM is basic. but has some redeeming qualities for a hobbyist
working with low voltages like battery powered toys. grill igniters are not on the list.  ::)  also its not my only DMM on the bench.  reminds me, did Dave fix that piezo mosquito problem he had in his own branded DMM.


The 235 I bought did not have the audio problem.  Just the connectors were not fitted very well. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline retiredcaps

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #282 on: July 21, 2017, 03:57:00 am »
Voltlog posted this video.  I haven't watched it yet, but I thought I would share.

 
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Offline G7PSK

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #283 on: July 21, 2017, 07:29:57 am »
That shutterstock photo is exactly that a Stock photo with a model posing with the neon screwdriver and a switch panel that is most likely standing on a bench, the neo light is the bit photo-shopped in. No doubt for the requisite fee you can have the photo for your own advertising without the water mark.
All the big power switch banks that I have seen cannot be opened with the power on due to mechanical interlocks, and I have seen a few big switch panels in my life as I used to build and service big gen sets at one time.
 

Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #284 on: July 21, 2017, 08:17:23 am »
I did notice he kept his fingers as far back as possible.  Well away from the shaft and tip.

That has to count for something.

Not in every shot.



The neon glow on his finger there looks very real to me.


Apparently the head torch works! They did some shots in the dark.

The darkness reveals some green LEDs on the breakers. Does green mean "OK!" or "safe to poke at"?

That shutterstock photo is exactly that a Stock photo with a model posing with the neon screwdriver and a switch panel that is most likely standing on a bench

Might be true if there were no photos of the surroundings.

I don't think body-capacitance is enough for a neon-lamp that bright, 600VAC 60Hz 100pF I get Xc=26MEG and 19uA.
The glow is visible with just microamps of current. 19uA would be fairly bright. The voltage drop across the neon is something like 70V.

Someone probably did a bit of photoshopping in the photo to make it brighter.

This is Russia! Russia is famous for their neons, Nixie tubes, etc. IT stands to reason that their screwdrivers are brighter.


(How did we get from "$25 multimeter" to this?)
« Last Edit: July 21, 2017, 08:46:10 am by Fungus »
 
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Offline EEVblog

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #285 on: July 21, 2017, 10:32:49 am »
I've now had three Aliexpress companies that sell the AN8008 (or their own branded one) and wanting me to promote their store  ::)
You mean they want you to put a link to their store in the video?
What sort of $$$ were they offering?  >:D

I don't care. I automatically turn down all sponsored or paid video review requests.
 

Offline cezar

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #286 on: July 21, 2017, 03:51:51 pm »
anyone got hands on this?
https://www.aliexpress.com/store/product/ZEAST-282-20000counts-Digital-Multimeter-True-RMS-4-1-2-Auto-Range-Voltmeter-Current-Ohm-Resistance/1490693_32819174795.html

it's only $10 more expensive (well... I know it's 40% more) but seems like much more capable.


 

Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #287 on: July 21, 2017, 03:56:57 pm »
anyone got hands on this?
https://www.aliexpress.com/store/product/ZEAST-282-20000counts-Digital-Multimeter-True-RMS-4-1-2-Auto-Range-Voltmeter-Current-Ohm-Resistance/1490693_32819174795.html

it's only $10 more expensive (well... I know it's 40% more) but seems like much more capable.

Looks amazing, specs are up there with a Fluke 87V. More meter than I'll ever need.




I dunno though. The workmanship of the input jacks may be exquisite but the design's only "reasonable".  :o

(insert the pen smoothly but firm. Oh, baby).
« Last Edit: July 21, 2017, 04:03:05 pm by Fungus »
 

Offline ebastler

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #288 on: July 21, 2017, 04:12:23 pm »
Revolutionary! The first 4 1/2 digit multimeter with only 4 digits in the display.
If the other specs are as credible, I'll pass on it...

EDIT: I see that they have photos of two slightly different meters in that product description. They seem to have added space for the extra "1" in a revised version.

« Last Edit: July 21, 2017, 04:15:53 pm by ebastler »
 

Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #289 on: July 21, 2017, 04:14:13 pm »
Revolutionary! The first 4 1/2 digit multimeter with only 4 digits in the display.
If the other specs are as credible, I'll pass on it...

I think I could get an AN8002 and an AN8008 for the same price and do more work than with one of those.

The only other thing I might need from a meter is safety. I'm betting that one doesn't have it, despite the CAT IV marking on the front.
« Last Edit: July 21, 2017, 04:28:01 pm by Fungus »
 

Offline kalel

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #290 on: July 21, 2017, 05:41:26 pm »
Revolutionary! The first 4 1/2 digit multimeter with only 4 digits in the display.
If the other specs are as credible, I'll pass on it...

I think I could get an AN8002 and an AN8008 for the same price and do more work than with one of those.

The only other thing I might need from a meter is safety. I'm betting that one doesn't have it, despite the CAT IV marking on the front.

Also, it comes with no USB connectivity? I think that there are meters with that option at that price range. Although, their specs might not match, but still, logging can be useful.
 

Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #291 on: July 21, 2017, 07:32:37 pm »
Also, it comes with no USB connectivity? I think that there are meters with that option at that price range. Although, their specs might not match, but still, logging can be useful.

Yeah, if you could get logging that might be useful.

 

Offline plazma

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #292 on: July 21, 2017, 07:36:34 pm »
There are many multimeters with the same DTM0660 chip as in Aneng AN8002 but with logging built in or TX pin bonded. However they are much larger in size except Victor VC-921.
 

Offline cjs

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #293 on: July 22, 2017, 01:39:16 am »
Revolutionary! The first 4 1/2 digit multimeter with only 4 digits in the display.

I'm pretty sure you're being sarcastic here, and ha ha, but just in case someone else doesn't get it:

Incorrect photos are not unusual. The meter is actually pretty similar in specs to the (in)famous UT61E (the most notable difference to my eye is that it lacks a 2 A current range), and there are a lot of pictures of the UT61E with the correct model name on the meter but showing the rather different display of the UT61A through D models. My guess would be that a lot of shops have a graphics guy to whom they hand photos to be cleaned up and they get "cleaned up" without much care as to which photos were actually used to assemble the final image.

In this case, looking at the images below taken from this store's link, the first one I would guess is from a different, lower-count meter; note the lack of space for a "1" digit between the "AC" indication and the four digits and, much more damning, the lack of a secondary display or bar graph. The second image looks as if it's a correct display; there's only four digits but there is space for a presumably non-iluminated "1" digit at the left. And the third image of course shows that there is indeed a "1" digit there.

I always get nervous, though, when looking at shops displaying what is ostensibly the meter I'd be buying but with the wrong display. This guy is $7 cheaper than this guy for what is supposed to be, but doesn't look like, the same meter.

(And hey, since we're totally off topic at this point anyway, now that I've learned much about people feelings toward meter labeling, anybody want to discuss how the ZEAST 282 compares to the UT61E, besides the obvious lack of serial data output?)
 

Offline MacMeter

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #294 on: July 22, 2017, 03:00:35 am »
Back on topic:
Searched the Internet, could not find a PDF manual for this "AN8008 True-RMS Digital Multimeter". Anyone know of a download link? Thanks!
 

Offline alm

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #295 on: July 22, 2017, 06:40:26 am »
Already posted by you here (and has since been answered). Please do not post the same question multiple times. It makes people waste time answering a question that may already be answered and splits discussions. It is bad enough having two threads about the same meter; please do not make it worse.
 

Offline b_force

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #296 on: July 22, 2017, 09:46:13 am »
Maybe it's a good idea to combine the topics, or pick just one?
It's pretty difficult to keep track on both (and what is shared in both)
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

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Offline JanJansen

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #297 on: July 22, 2017, 11:18:06 am »
That new movie measures nothing, they only talk about daves movie and say the same stuff, bad movie.
Someone making movie with measuring results please ?, oh wait, no one has that expensive calibration stuff.
aliexpress parachute
 

Offline joeqsmith

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #298 on: July 22, 2017, 07:38:58 pm »
Harbor Freight also gives away these beauties. The convenient on/off switch means the selector can literally be in any position when junior connects the probes.



I guess anyone, not just Jr, could have the selector literally in any position when we connect the probes to the meter or to the target. 

As far as multimeter safety sins go, the "convenient on/off switch" is one of the worst. Fake CAT ratings pale by comparison.

Just think of the children!

Under what conditions do you feel having a separate on/off switch makes a handheld multimeter less safe than one where the function is built into the rotary selector?

Do you feel the separate mechanical on/off switch is less safe than an electronic one? 

What about meter's that can be powered up by remote?

What about meters that go into sleep mode and you rotate the selector to wake them?
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline alm

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #299 on: July 22, 2017, 07:57:46 pm »
Not Fungus, but my $0.02.

Under what conditions do you feel having a separate on/off switch makes a handheld multimeter less safe than one where the function is built into the rotary selector?
I do not think it is a big deal. The meter should be safe regardless of the switch and leads configurations. So powering on a meter with the switch set to current should not be a safety issue. That this is almost certainly not the case with this particular meter is a different issue.

Of course it can blow an (expensive) fuse or trip a breaker, shutting down a mains circuit. But those are not safety issues (unless there was a pre-existing one like a locked door that cannot be opened without electricity). I do not think it is an amazing design in combination with the shared current jacks. But I remember bench meters that used ganged switches for function switch (so it would be persistent across power off). They had a separate power button. And some had a shared V/mA socket. Never had any problems with that.

Do you feel the separate mechanical on/off switch is less safe than an electronic one? 
Since power on/off on a DMM will not usually affect safety and function selection or voltage at/current through the test leads, I do not think this matters at all. Meters that use soft switching for functions (e.g. any modern bench meter) will usually default to a high impedance (e.g. DCV) state on power on.
 


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