Author Topic: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter  (Read 299392 times)

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Offline mnementh

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #625 on: September 17, 2017, 05:00:18 am »
I've had problems in both hertz dial positions. So far I can't reliably reproduce the problems. In the first dial position for hertz and voltage, I get no readings for hertz at times, but can get a reading in the dedicated hertz dial position, then at times this behavior is just the opposite.

The AC mode "Hertz" function is probably only for low frequencies (mains AC).

The dedicated Hz function will probably go much higher.

If you don't get a reading, try swapping the leads around. These meters often need a zero crossing to work. eg. My AN860B+ only measures the frequency of Arduino pins when the leads are connected "backwards".

All my tests have been on 60 Hz sources, the Geny is a 3-phase crystal sync. However, come Monday I'll try your suggestion of reversing the leads. Thanks.

I'm thinking this may be the cause of your erratic readings. The meter may not be properly designed to count 3-phase AC; only single-phase.

As for those worrying about using it on mains... I could see if you were talking 440 or even 240VAC; but 120VAC? Hell... one of the old codgers (admittedly, a bit off in general, but still) I used to work with at the Ding & Dent Appliance store would use two fingers of one hand to test for presence of live AC when puttering around inside of microwaves and the like. 120VAC really still qualifies as "low-voltage" IMO; hell I've seen 12VDC powered amplifiers with +80V and -80V rails.


Cheers,


mnem
"Electrons may be very, very tiny; but when they gang up on you they always win." ~ me
« Last Edit: September 17, 2017, 05:02:04 am by mnementh »
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Offline MacMeter

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #626 on: September 17, 2017, 11:44:32 am »
Quote
I'm thinking this may be the cause of your erratic readings. The meter may not be properly designed to count 3-phase AC; only single-phase.

As for those worrying about using it on mains... I could see if you were talking 440 or even 240VAC; but 120VAC? Hell... one of the old codgers (admittedly, a bit off in general, but still) I used to work with at the Ding & Dent Appliance store would use two fingers of one hand to test for presence of live AC when puttering around inside of microwaves and the like. 120VAC really still qualifies as "low-voltage" IMO; hell I've seen 12VDC powered amplifiers with +80V and -80V rails.
Cheers, mnem
"Electrons may be very, very tiny; but when they gang up on you they always win." ~ me

I'm only reading a single phase at a time, voltage readings are accurate on each phase to neutral. It's the two "hertz" settings that act oddly, it could be the contacts in the meters "switch". I'll try to document the behavior in more detail this week, for those that like a good mystery.

And yes, I've heard the stories of the "old timers" using their fingers to detect voltage, never felt compelled to do it myself. Almost all of electrical readings I do are outside or in a studio, open air settings, temporary installations typical of most film and TV sets and locations. The few times I have to read a mains box in an electric closet or room, I would only probe with a "SAFE" meter. Most of the voltage we are exposed to is 120v. AC, and 220v AC measured between the generator phases. There are times when more power is needed in an underpowered studio, and the they rent one or two MegaWatt CAT generators that put out 480v AC, step down transformers are then used.
« Last Edit: September 17, 2017, 11:48:45 am by MacMeter »
 

Offline Mr. Scram

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #627 on: September 17, 2017, 02:58:21 pm »
I'm thinking this may be the cause of your erratic readings. The meter may not be properly designed to count 3-phase AC; only single-phase.

As for those worrying about using it on mains... I could see if you were talking 440 or even 240VAC; but 120VAC? Hell... one of the old codgers (admittedly, a bit off in general, but still) I used to work with at the Ding & Dent Appliance store would use two fingers of one hand to test for presence of live AC when puttering around inside of microwaves and the like. 120VAC really still qualifies as "low-voltage" IMO; hell I've seen 12VDC powered amplifiers with +80V and -80V rails.


Cheers,


mnem
"Electrons may be very, very tiny; but when they gang up on you they always win." ~ me
I know of plenty of smokers who could tar a ship with what went in their lungs each week and still died of old age, but I still wouldn't recommend it to anyone. MacMeter does seem to use it on 240V.

However, I'm not trying to be a safety nanny here. It's not criticism as such. I'm just interested in real life use I would consider a bit beyond the hardware. Even though I do things differently, it's an interesting opportunity to learn. I have been wondering whether anyone uses the AN8008 on mains on a regular basis and how that works out.
 

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #628 on: September 17, 2017, 03:53:01 pm »
I know of plenty of smokers who could tar a ship with what went in their lungs each week and still died of old age, but I still wouldn't recommend it to anyone.

I'm sure there's plenty of people using DT830Bs on mains AC on a daily basis but I'd like to think that not many of them reside here.


I have been wondering whether anyone uses the AN8008 on mains on a regular basis and how that works out.

a) If it's always used correctly on the AC setting then probably nothing spectacular will happen. Safety features are for when you mess up, right?

b) If it simply dies a quiet death then "Crappy China" will be blamed, not the person who chose the meter.

 

Offline mnementh

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #629 on: September 17, 2017, 10:02:01 pm »
Quote
I'm thinking this may be the cause of your erratic readings. The meter may not be properly designed to count 3-phase AC; only single-phase.

As for those worrying about using it on mains... I could see if you were talking 440 or even 240VAC; but 120VAC? Hell... one of the old codgers (admittedly, a bit off in general, but still) I used to work with at the Ding & Dent Appliance store would use two fingers of one hand to test for presence of live AC when puttering around inside of microwaves and the like. 120VAC really still qualifies as "low-voltage" IMO; hell I've seen 12VDC powered amplifiers with +80V and -80V rails.
Cheers, mnem
"Electrons may be very, very tiny; but when they gang up on you they always win." ~ me

I'm only reading a single phase at a time, voltage readings are accurate on each phase to neutral. It's the two "hertz" settings that act oddly, it could be the contacts in the meters "switch". I'll try to document the behavior in more detail this week, for those that like a good mystery.

And yes, I've heard the stories of the "old timers" using their fingers to detect voltage, never felt compelled to do it myself. Almost all of electrical readings I do are outside or in a studio, open air settings, temporary installations typical of most film and TV sets and locations. The few times I have to read a mains box in an electric closet or room, I would only probe with a "SAFE" meter. Most of the voltage we are exposed to is 120v. AC, and 220v AC measured between the generator phases. There are times when more power is needed in an underpowered studio, and the they rent one or two MegaWatt CAT generators that put out 480v AC, step down transformers are then used.



Ummm... okay... so tell me, exactly how are you measuring individual phases with just a meter?

Last I knew, we still needed a 'scope for that. All 3 phases are still present on each leg; you can't ever get away from that. If your meter is made with a simple rectifier and notch filter designed for measuring single-phase AC, it's going to be totally out to lunch measuring 3-phase. This is one of the big differences between a Radidio Shack cheapie and a decent industrial meter; I suspect you may be falling into a similar trap here, especially after reading elsewhere about how all the clone meters are doing away with every last component they can get away with "...just to save 0.0001 per unit".

As for the old-timers doing stuff we'd consider daft; I never said I thought it was a good idea. But measuring an AC source you know to be 120V? I certainly wouldn't be afraid to use even the HFT "Little Red Box of Damifino" for that. Smeesh.

What's the best meter in the world? The one you have WHEN YOU NEED IT.


Good hunting,


mnem
In other news...

« Last Edit: September 17, 2017, 10:18:57 pm by mnementh »
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Offline bitseeker

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #630 on: September 17, 2017, 10:03:55 pm »
Is the "value" of the HF free meter inflating?
TEA is the way. | TEA Time channel
 
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Offline joeqsmith

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #631 on: September 17, 2017, 10:13:47 pm »
Is the "value" of the HF free meter inflating?
:-DD :-DD :-DD
 
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Offline mnementh

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #632 on: September 17, 2017, 10:18:08 pm »
Is the "value" of the HF free meter inflating?

Clearly, the "Lil' Red Box of Damifino" is feeling the pressure of the "'Sghetti Meter"...  :bullshit:  :-DD :-DD :-DD


mnem
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Offline texaspyro

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #633 on: September 17, 2017, 10:53:30 pm »
Does anybody have the calibration procedure for the Ragu 17B?  Mine is reading around 10% low on the DC volts (< 6V) and resistance range.

I thought I saw it somewhere in this thread, but can't seem to find it...
 

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #634 on: September 17, 2017, 11:46:43 pm »
I thought I saw it somewhere in this thread, but can't seem to find it...

If you saw anything it would have been for the meter this thread is about.  :-//
 

Offline texaspyro

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #635 on: September 18, 2017, 12:06:18 am »
I thought I saw it somewhere in this thread, but can't seem to find it...

If you saw anything it would have been for the meter this thread is about.  :-//

Yes, but this is the only thread that even mentions the Ragu meters...
 

Offline Mr. Scram

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #636 on: September 18, 2017, 12:09:33 am »
Yes, but this is the only thread that even mentions the Ragu meters...
Time for a dedicated one, I guess :)
 

Offline IanB

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #637 on: September 18, 2017, 01:06:52 am »
Ummm... okay... so tell me, exactly how are you measuring individual phases with just a meter?

Last I knew, we still needed a 'scope for that. All 3 phases are still present on each leg; you can't ever get away from that. If your meter is made with a simple rectifier and notch filter designed for measuring single-phase AC, it's going to be totally out to lunch measuring 3-phase.

This is of course not true!

If you measure between two legs of a three phase supply, or between one leg and neutral in a star system, then you will see a single phase AC voltage waveform. If this wasn't true then the whole electrical distribution system in the UK would be impossible, since nearly all homes and business premises in the UK are supplied from three phase distribution transformers, and all homes have a single phase AC supply.

So yes, you can easily get away from three phases in a three phase system. Just measure a single phase.
« Last Edit: September 18, 2017, 01:08:50 am by IanB »
 

Offline mnementh

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #638 on: September 18, 2017, 03:09:39 am »
Mmmokay... I know I've seen it demonstrated otherwise; all 3 phases visible in a single trace at the same time on a single leg. Is this a Delta vs Wye thing, or perhaps a 3-phase transformer thing that I've just mis-remembered?

I know that with a Wye-wound load you have an artificial neutral; perhaps that was related to the transform between Delta wound source and Wye-wound load. Dammit... now you've got me wondering what the hell it was they were showing when I saw that... I remember being amazed when they showed how it was connected.


mnem
I think I'm gonna declare this one a case of temporary stupidity and move on with my life.
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Offline tooki

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #639 on: September 19, 2017, 02:37:48 pm »
Forgive my naivety, but what's wrong if it comes from China? Mine took about 2.5 weeks, but no problems so far with the meter. just no box.

Some people want it NOW, DAMMIT!

I wait since 5 weeks to get mine from Bangood. |O
I think they use the cheapest way to ship. :horse:
Just a data point, I ordered one from banggood for $17.77 on Sep 3, it shipped the next day, and was delivered yesterday on the 18th, 2 weeks on the dot.
 

Offline Mr. Scram

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #640 on: September 19, 2017, 11:33:22 pm »
I just received my second AN8008 and it seems to have taken 8 days. In both cases, delivery was ridiculously quick. Both came from the same seller. The serial numbers are only twohundredsomething apart, which doesn't seem too unlikely coming from the same source with only three weeks between them. What surprised me a bit is that the beep or buzzer of the new unit isn't by far as loud as the one of the first unit. I have taken them both apart to check for any differences, but there isn't anything visible that would explain why one is much louder than the other. The boards look exactly identical, with the lone exception being the oscillator packages that are installed rotated a 180 degrees with respect to each other. The hand soldered joiints don't seem to look as neat as the machine soldered ones, with some component legs having very little solder.

Calibration hasn't been checked. That will be something to do in the near future.
 

Offline b_force

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #641 on: September 20, 2017, 10:27:02 am »
Cheap piezo buzzers can have quite some tolerance in them.

Offline daybyter

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #642 on: September 20, 2017, 11:45:36 am »
Did you exchange the test leads? Cleaning the tips of my 830 test Leeds with some sanding and alcohol made the buzzer louder.
 

Offline Mr. Scram

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #643 on: September 20, 2017, 03:13:19 pm »
Did you exchange the test leads? Cleaning the tips of my 830 test Leeds with some sanding and alcohol made the buzzer louder.
It's not just in the continuity mode, but also when operating the switch when no leads are involved.
 

Offline tooki

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #644 on: September 20, 2017, 04:31:17 pm »
Did you exchange the test leads? Cleaning the tips of my 830 test Leeds with some sanding and alcohol made the buzzer louder.
It’s a (surprisingly good) latching continuity mode, the contact resistance of the test leads has no relation to the loudness.
 

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #645 on: September 20, 2017, 04:36:09 pm »
Did you exchange the test leads? Cleaning the tips of my 830 test Leeds with some sanding and alcohol made the buzzer louder.

It shouldn't make any difference to the buzzer volume. The buzzer will be triggered by a comparator (or something similar).
 
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Offline tooki

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #646 on: September 20, 2017, 04:40:57 pm »
Did you exchange the test leads? Cleaning the tips of my 830 test Leeds with some sanding and alcohol made the buzzer louder.

It shouldn't make any difference to the buzzer volume. The buzzer will be triggered by a comparator (or something similar).
Not only that, but in the AN8008 it’s latched, so it’s the MCU driving the buzzer.
 

Offline Mr. Scram

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #647 on: September 20, 2017, 04:49:23 pm »
It occurred to me that the battery voltage might play a role in this, even though I put what I thought to be fresh batteries in both. I just swapped the batteries of the two units, but that doesn't make a difference.

I also already encountered the gap between the milliamp and microamp range, which is a bit disappointing. I got confused by the different readings for a while, until I realised the AN8008 actually shows a consistent change in readings when you have plugged the leads into the wrong sockets. You get perfectly consistent but incorrect readings when you use the microamp scale, but plug the leads for the milliamp scale. It doesn't help that both units show the exact same wrong reading.
« Last Edit: September 20, 2017, 04:58:32 pm by Mr. Scram »
 

Offline retrolefty

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #648 on: September 20, 2017, 05:05:15 pm »
I just received my second AN8008 and it seems to have taken 8 days. In both cases, delivery was ridiculously quick. Both came from the same seller. The serial numbers are only twohundredsomething apart, which doesn't seem too unlikely coming from the same source with only three weeks between them. What surprised me a bit is that the beep or buzzer of the new unit isn't by far as loud as the one of the first unit. I have taken them both apart to check for any differences, but there isn't anything visible that would explain why one is much louder than the other. The boards look exactly identical, with the lone exception being the oscillator packages that are installed rotated a 180 degrees with respect to each other. The hand soldered joiints don't seem to look as neat as the machine soldered ones, with some component legs having very little solder.

Calibration hasn't been checked. That will be something to do in the near future.

 I too bought a second unit (gave the first to a friend) about a month apart but from a second seller on e-bay. My buzzer is barely audible. I too took mine apart to investigate. Found putting some tape over the hole made it twice as loud but still weak for my old hearing. Kind of a bummer but I don't rely on the buzzer much anyway and I still think this a nice cute DMM.

 

Offline flywheelz

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #649 on: September 20, 2017, 07:11:31 pm »
Could someone compare the frequency the buzzers are running at?  Loud vs Quite.  Perhaps they started using different batch of buzzers that require a different frequency, even 500Hz off make a huge difference.
 


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