Author Topic: EEVblog #1007 - Is a $25 Multimeter Any Good  (Read 94205 times)

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Offline kalel

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #400 on: August 09, 2017, 09:54:53 am »
Got mine the other day. It's very cute and small. Seems to be accurate in the voltage ranges as well.





Good results. :)
 

Online Specmaster

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #401 on: August 09, 2017, 10:57:07 am »
Can't argue with those results can you?
Who let Murphy in?
 

Offline kalel

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #402 on: August 09, 2017, 11:13:12 am »
Can't argue with those results can you?

Pretty amazing. If we look at low voltage uses of these things, they seem to be great value.
 

Offline FrankBuss

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #403 on: August 09, 2017, 01:27:31 pm »
Got my new Fluke 8842A, and I built a simple test circuit with two 1.5V batteries, two 1 meg resistors, a precision 10k trim pot for the offset, in parallel to one battery a 56k resistor for a smooth voltage ramp (a pot was too noisy), and a 1uF Wima film capacitor parallel to the measurement. Then no breathing or moving for 5 minutes, and I could measure this:



+/-5uV deadband confirmed, but no hysteresis. I would say it is perfect for 10uV resolution for this price.

I know, I really have to clean up my workbench :=\
So Long, and Thanks for All the Fish
Electronics, hiking, retro-computing, electronic music etc.: https://www.youtube.com/c/FrankBussProgrammer
 
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Offline JanJansen

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #404 on: August 09, 2017, 02:49:28 pm »
The crocodile cables that are include break off after measuring about 100 capacitors, the screw-able cables are worthless,
Now i have to look to proper crocodile cables, do they all fit in ?
aliexpress parachute
 

Offline metrologist

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #405 on: August 09, 2017, 03:58:11 pm »
Got my new Fluke 8842A, and I built a simple test circuit with two 1.5V batteries, two 1 meg resistors, a precision 10k trim pot for the offset, in parallel to one battery a 56k resistor for a smooth voltage ramp (a pot was too noisy), and a 1uF Wima film capacitor parallel to the measurement. Then no breathing or moving for 5 minutes, and I could measure this:


+/-5uV deadband confirmed, but no hysteresis. I would say it is perfect for 10uV resolution for this price.

I know, I really have to clean up my workbench :=\

Now I am envious, you actually have space to set your meter on the bench without balancing and other things sliding off... Sadly, I looked for that Fluke after Dave's video. The 8008 did not come.
 

Offline retrolefty

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #406 on: August 09, 2017, 04:34:31 pm »
Quote
If I had the choice in a situation like this, I would strongly lean towards having a noisy measurement than a 'cleaned up' one.  At least with the noisy one, I would see the fluctuations - which would remind me of this limitation or prompt me to check if this was normal.  With a "cleaned up" reading - I just wouldn't have any indication ...

 In our industrial DCS systems in a refinery, a tech could call up the 'raw reading' signal reading to disable any 'zero clamping' filtering on the sensor reading being looked at. Operators liked nice quite zero readings and techs liked to see the actual noise on live signals if they wished, win...win.


 

Online Brumby

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #407 on: August 10, 2017, 07:54:40 am »
Operators liked nice quite zero readings and techs liked to see the actual noise on live signals if they wished, win...win.

That is exactly where my thinking lies.  For the operator, the zero null would be adequate, but the techs have the same interest that I do.
 

Online Specmaster

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #408 on: August 10, 2017, 08:45:03 am »
Got my new Fluke 8842A, and I built a simple test circuit with two 1.5V batteries, two 1 meg resistors, a precision 10k trim pot for the offset, in parallel to one battery a 56k resistor for a smooth voltage ramp (a pot was too noisy), and a 1uF Wima film capacitor parallel to the measurement. Then no breathing or moving for 5 minutes, and I could measure this:



+/-5uV deadband confirmed, but no hysteresis. I would say it is perfect for 10uV resolution for this price.

I know, I really have to clean up my workbench :=\
That update is so s l o w though that I can't help but feel that if the extra digits are that important, (in certain situations I can see that they could be) then for them to be meaningful, especially if you needed to interact with the device under test when a critical point was reached at all, that you need the update speed of the bench meter at least? At the moment it is lagging badly behind and what ever the point that you needed to interact with it, to possibly switch off to prevent damage to the project etc being developed and tested, that it would be too late anyway.
Who let Murphy in?
 

Offline kalel

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #409 on: August 10, 2017, 09:05:39 am »
Got my new Fluke 8842A, and I built a simple test circuit with two 1.5V batteries, two 1 meg resistors, a precision 10k trim pot for the offset, in parallel to one battery a 56k resistor for a smooth voltage ramp (a pot was too noisy), and a 1uF Wima film capacitor parallel to the measurement. Then no breathing or moving for 5 minutes, and I could measure this:



+/-5uV deadband confirmed, but no hysteresis. I would say it is perfect for 10uV resolution for this price.

I know, I really have to clean up my workbench :=\
That update is so s l o w though that I can't help but feel that if the extra digits are that important, (in certain situations I can see that they could be) then for them to be meaningful, especially if you needed to interact with the device under test when a critical point was reached at all, that you need the update speed of the bench meter at least? At the moment it is lagging badly behind and what ever the point that you needed to interact with it, to possibly switch off to prevent damage to the project etc being developed and tested, that it would be too late anyway.

If speed is more important than accuracy, perhaps an automated system might be best, that switches off the project at certain value. Otherwise, you have your own reaction time to factor in.
 

Offline FrankBuss

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #410 on: August 10, 2017, 10:56:58 am »
Got my new Fluke 8842A, and I built a simple test circuit with two 1.5V batteries, two 1 meg resistors, a precision 10k trim pot for the offset, in parallel to one battery a 56k resistor for a smooth voltage ramp (a pot was too noisy), and a 1uF Wima film capacitor parallel to the measurement. Then no breathing or moving for 5 minutes, and I could measure this:



+/-5uV deadband confirmed, but no hysteresis. I would say it is perfect for 10uV resolution for this price.

I know, I really have to clean up my workbench :=\
That update is so s l o w though that I can't help but feel that if the extra digits are that important, (in certain situations I can see that they could be) then for them to be meaningful, especially if you needed to interact with the device under test when a critical point was reached at all, that you need the update speed of the bench meter at least? At the moment it is lagging badly behind and what ever the point that you needed to interact with it, to possibly switch off to prevent damage to the project etc being developed and tested, that it would be too late anyway.

I don't think it is lagging behind. The update rate of the AN8008 looks like more than 1 sample per second, but it might have an offset. That's tricky, you can't tell it has an offset by shorting the leads, because of the dead spot.

The Fluke can be changed to insane speed (manual says 33 samples per second for this range) which you can't read anymore, if you need only 1 uV resolution instead of 0.1 uV, which can be very useful in combination with GPIB and automated measurements.
So Long, and Thanks for All the Fish
Electronics, hiking, retro-computing, electronic music etc.: https://www.youtube.com/c/FrankBussProgrammer
 

Online Specmaster

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #411 on: August 10, 2017, 01:38:32 pm »
Well compared to your Fluke it is certainly lacking on some occasions it is very noticeable indeed.
Who let Murphy in?
 

Online Brumby

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #412 on: August 11, 2017, 12:50:25 am »
I couldn't get much past this...
Well compared to your Fluke .....
 

Offline floobydust

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #413 on: August 11, 2017, 12:54:40 am »
[snippet]

...  +/-5uV deadband confirmed, but no hysteresis. I would say it is perfect for 10uV resolution for this price.

I do see hysteresis on the DCV function, but not noticable on uV. I observe it needs to read a value one or two counts over the present reading before it updates the display.

I can see the AN8008 meter uses a slow and fast filter in software, for display. The slow filter is ~2seconds. The fast is msec I'm guessing.
For fast changing signals, the meter uses the fast filter's value and if/when the derivative settles, it switches to displaying the slow-filter's value.
If you quickly connect the probes from 0V to 5.000V, it sometimes grabs (fast filter value) 4.930V and after 2 seconds goes to show (slow filter value) 5.000V
For quick changes slow filter gets "primed" by the fast filter, to speed display response time.
It's not perfect but works well enough if you wait.
 

Offline floobydust

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #414 on: August 11, 2017, 01:01:10 am »
I couldn't get much past this...
Well compared to your Fluke .....

Actually, it's not far off.
 
In china they are envious of Fluke multimeters, considered the ultimate, like owning Gucci or Mercedes but far too expensive for the masses. They are after them...
Reading the chinese forums, these multimeters appear to be a result of communism.

The government mandated the need for low-cost precision multimeters, in order to improve the nation.
The result is planning and fab of single-chip DMM IC's, which make these low dollar meters possible.
There is great national pride in this accomplishment. 
 

Online Specmaster

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #415 on: August 11, 2017, 09:14:58 am »
I couldn't get much past this...
Well compared to your Fluke .....
I'm not sure what you're saying here but from my part it was a  typo, it should read "Well compared to your Fluke, it is lagging, on some occasions it is very noticeable indeed."

To my mind the extra digit is very useful in tracking down short circuits as it allows the user to see if they moving towards or away from the location of the short and in that context the update speed is not so critical.
Who let Murphy in?
 

Online Brumby

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #416 on: August 11, 2017, 11:53:18 am »
It's simple.

Comparing a Fluke to a $25 el cheapo is a great way for me to not take great interest in the rest of the sentence.


Probably an over-reaction, so I'm sorry for that.
 

Offline b_force

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #417 on: August 12, 2017, 01:57:45 pm »
It's simple.

Comparing a Fluke to a $25 el cheapo is a great way for me to not take great interest in the rest of the sentence.


Probably an over-reaction, so I'm sorry for that.
Don't see why Fluke needs to be the holy God here?
Just use multimeters (or any kind of equipment) for what it's good for.

So there are enough situations that you perfectly can compare a $25 meter with a Fluke.
In some situations the Fluke will be less, in others a $25 multimeter will be less.
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

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Offline _roger_

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #418 on: August 25, 2017, 11:08:38 am »
hello, just a little information.

IS possible has min/max or peak function?Link of mod? :D
 

Offline plazma

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #419 on: August 25, 2017, 11:34:21 am »
hello, just a little information.

IS possible has min/max or peak function?Link of mod? :D
AN8002 can be modified to have extra buttons. The same modifications did not work with AN8008.
 

Offline _roger_

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #420 on: August 25, 2017, 12:19:42 pm »
So is not possible a mod to have peak function? :(
thanks for the info man
 

Offline PeteAU

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #421 on: September 02, 2017, 11:22:56 am »
I jumped on the AM8008 bandwagon and had some issues. It was showing 300-something volts when measuring 3.3DCV signal.
Anyone else had this problem? Pressing down on the range switch seems to have fixed it (for now?)...
 

Offline plazma

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #422 on: September 02, 2017, 11:26:59 am »
I've had some problems with wrong measurement and missing function. They were always caused by misaligned contacts on the dial. They may get misaligned when opening and modifying the unit.
 

Offline floobydust

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #423 on: September 04, 2017, 12:48:53 am »
My AN8008 died and couldn't do ohms. Either the decimal point jumped around constantly or getting wandering 40-60ohms with input jack shorted. Test leads are ok. Checked all soldering re-did PTC but same problem.

Looks like oxide on the rotary switch contacts, spun it back and forth a few times and it's ok for now.

Gold on the PCB with copper alloy for the wiper, I guess the metal is crap, or the Krytox lube I used is causing troubles.


 

Online Brumby

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #424 on: September 04, 2017, 04:04:45 am »
I caved.

For the $22.62 it cost me (with a 2-4 week wait) it's not going to sink the ship.
 


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