Author Topic: Another cheapo multimeter: 19999 count, 0.05% DC accuracy  (Read 10483 times)

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Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #50 on: April 18, 2018, 04:07:45 am »
Thank you. The first teardown big picture is missing

I had type the wrong picture number, it is fixed now.


The AN870 seems to have about twice the usable frequency for TrueRMS, half a digit extra on most measurements, otherwise very similar.

How do you get that, they both drop just above 2kHz, i.e. RMS needs considerable lower frequency to work.

PS: how well does the NCV tester work? Can it detect wires in walls?

I have a wall without wires in that most NCV tester signals on. NCV is fairly difficult to compare because how you hold the meters is one of the parameters for sensitivity. If you have your hand around the meter and the wire is just behind a very thin wall it might give alarm.

 

Online Fungus

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #51 on: April 18, 2018, 04:16:47 am »
Looks like the accessories vary with brand....  :popcorn:
 

Offline 001

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #52 on: April 18, 2018, 04:53:03 am »
Can I  power AN870 with two AA NiMH cells ?
 

Online Fungus

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #53 on: April 18, 2018, 04:54:18 am »
The AN870 seems to have about twice the usable frequency for TrueRMS, half a digit extra on most measurements, otherwise very similar.

How do you get that, they both drop just above 2kHz, i.e. RMS needs considerable lower frequency to work.

The AN860B+ is 5% down at 1kHz, 12% down at 2kHz.

(although it is quite linear up to 2kHz so you can still take measurements if you know that)

You say the AN870 is 5% down at 2kHz, that's half as much.   :)

 

Online Fungus

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #54 on: April 18, 2018, 04:55:30 am »
Can I  power AN870 with two AA NiMH cells ?

The test says:
Code: [Select]
Meter works down to 2.2V where it turns off, battery symbol show at 2.4V.
So it's your call.

(2.4V is quite high though, maybe this meter is suitable for Batteroo Batterisers!  8) )
« Last Edit: April 18, 2018, 04:57:09 am by Fungus »
 

Offline 001

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #55 on: April 18, 2018, 04:57:08 am »
 No?  :-//
 

Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #56 on: April 18, 2018, 04:59:59 am »
Can I  power AN870 with two AA NiMH cells ?

You cannot use the full runtime of them, the meter says empty battery at 2.41V, that would mostly work.

 
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Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #57 on: April 18, 2018, 05:03:23 am »
The AN870 seems to have about twice the usable frequency for TrueRMS, half a digit extra on most measurements, otherwise very similar.

How do you get that, they both drop just above 2kHz, i.e. RMS needs considerable lower frequency to work.

The AN860B+ is 5% down at 1kHz, 12% down at 2kHz.

(although it is quite linear up to 2kHz so you can still take measurements if you know that)

You say the AN870 is 5% down at 2kHz, that's half as much.   :)

My numbers says 2kHz and 5% for both meters, measured with a sinus. It is a fairly high order filter.
A square wave is only about 10% different from a sine wave.
 

Online Fungus

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #58 on: April 18, 2018, 07:03:18 am »
My numbers says 2kHz and 5% for both meters, measured with a sinus. It is a fairly high order filter.
A square wave is only about 10% different from a sine wave.

I was using a square wave, maybe that's the difference.
 

Offline 001

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #59 on: April 18, 2018, 07:59:56 am »
 what about temperature compensation ?
 

Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #60 on: April 18, 2018, 01:59:46 pm »
what about temperature compensation ?

Thats fairly standard with a temperature sensor inside the multimeter chip. The linearization for temperature input is good, it basically works from -200 to +1300°C
 
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Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #61 on: April 18, 2018, 05:29:03 pm »
As it says at the bottom of the review I got this meter from Banggood and after my review they decided to add some discount (I do not now if they raised the price before they did that  :) ), details are on my frontpage (Click globe).
 

Offline 001

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #62 on: April 18, 2018, 07:54:37 pm »
what about temperature compensation ?

Thats fairly standard with a temperature sensor inside the multimeter chip. The linearization for temperature input is good, it basically works from -200 to +1300°C

is it same circuit as qn860 or not?
 

Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #63 on: April 18, 2018, 09:29:12 pm »
what about temperature compensation ?

Thats fairly standard with a temperature sensor inside the multimeter chip. The linearization for temperature input is good, it basically works from -200 to +1300°C

is it same circuit as qn860 or not?

It is basically the same as AN860B+
 

Offline 001

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #64 on: April 18, 2018, 09:50:50 pm »

It is basically the same as AN860B+

Is it DTM0660 based?  :o
 

Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #65 on: April 18, 2018, 09:54:20 pm »

It is basically the same as AN860B+

Is it DTM0660 based?  :o

It is rather difficult to read the type number on a COB chip and I am not going to check the contents of the EEPROM.
 

Offline Stinger

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #66 on: April 19, 2018, 08:29:27 am »
Thank's for your job.  :-+

And about wrong temperature mesurement of AN860B+ brother ?
 

Offline 001

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #67 on: April 21, 2018, 04:20:27 am »
And about wrong temperature mesurement of AN860B+ brother ?

What about  AN860B+  temperature?  :-//
 

Online Fungus

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #68 on: April 21, 2018, 05:00:52 am »
What about  AN860B+  temperature?  :-//

I never had any problems with it.  :-//

 

Offline HKJ

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #69 on: April 21, 2018, 05:06:19 am »
And about wrong temperature mesurement of AN860B+ brother ?

What about  AN860B+  temperature?  :-//

Probably somebody that do not know how thermocouplers work, there are a couple of pitfalls.
I wrote a bit about it here: https://lygte-info.dk/info/DMMThermocouplers%20UK.html
 
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Offline gpu7990

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #70 on: May 03, 2018, 05:23:06 am »
Hello, can someone read eeprom from zt219 or AN870? Thanks
 

Offline lordvader88

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #71 on: May 03, 2018, 07:16:17 am »
So what's the verdict ? I need a 2nd DMM for breadboard level stuff and for upto 240V mains heaters/hotwater boilers, once in a blue moon. And I don't want to take my quality DMM out of my house.

So for $50 is a good choice for that ?
 

Offline Johnboy

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #72 on: May 03, 2018, 08:20:21 am »
The consensus seems to be that these cheapos, while useful for extremely low-current, low-voltage work, are not suitable for working with mains.
I do not think anyone here would suggest that the meters discussed in this particular thread can be considered "safe" for household use, let alone industrial applications. If safety is your concern, that is what you are paying for, not the meter.

I'm interested in this model because of what it can do at the lowest ranges, but I wouldn't trust my life to the diaphamous input protection on the device when working with higher voltages, and I don't recommend you do either.
« Last Edit: May 03, 2018, 08:28:10 am by Johnboy »
 

Online maginnovision

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #73 on: May 03, 2018, 08:21:18 am »
I am fairly certain one of mine died at 120v. The leads are junk and there is little protection in the meter. Get something else.
 

Offline lordvader88

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Re: Another cheapo multimeter: 19999 count, 0.05% DC accuracy
« Reply #74 on: May 03, 2018, 09:04:57 am »
Yeah rewatching some of Joe Smith's testing video's (of others), this thing has no amount of input protection MOVs or PTCs.
 


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