Big Clive's "Trashy" meter, unboxed ( Duratool D03047 multimeter )

[Fungus]

Gotta be impressed by Duratool...

Not only can they make a decent DT830 for €3.75, they can also make one with built-in network cable tester for €4.79:



(they managed to keep the transistor tester, too )

[xrunner]

That's pretty impressive for the price. Initially I thought the cable testing was performed by manually using the probes and checking the continuity by inserting them into the holes. But no - it has LEDs that indicate for you. 

[Nikola Tesla Junior IV]

... it would reside within 1 or 2 MM from the outside of the unit where you would be presumably be putting an appendage at some point in time.

Is that less than the insulation on a Fluke probe cable?

I would guess more.

Perhaps you do not understand the "skin effect" to its full potential. If such is true, then I can elaborate on my short answer to your question.

Its my opinion that it's an insult to include Fluke in the same discussion, and for my reasons, I would direct you to this  -->  https://www.fluke.com/en/learn/blog/safety/safe-test-tools-real-world-use

[joeqsmith]

Those free meters have gone through several hardware changes over the years to reduce cost.  Even if we saw a difference between the two meters I show, I couldn't tell you if it had anything to do with the label or not. 

Is 1100V the limit? Seems to me like a 2000 count meter should be able to display 2000V... 

Meter1 is the most recent marked 250V on selector.  Note how large print in the back "Do not test voltages over 250 volts". 
Meter2 is from when I started running these tests marked 1kV on selector. 
Meter3 is the oldest revision I have.

Note how the input has changed over the years to reduce cost.   As far as your thoughts on 2000 count meters should all handle 2kV.  I guess then the UT61E at 20k counts should handle 20kV and the 300k count GMW should handle 300,000 volts? 

Maybe you feel all meters should display a minimum of 2kVDC?  Again, I'm not shy about running them.  Maybe the 121GW, UT91E, the yellow and the latest at 2kV with the meters set to their highest DCV settings. 

***
There were a few people running a similar test using an insulation tester.   Of course, it folds back.  If we run it, the power supply will have enough power available to not fold back.    Are you going to perform the same test with one of your new meters as well? 

[robert.rozee]

from a chart on DigiKey's site (https://www.digikey.co.nz/en/blog/what-are-multimeter-cat-safety-ratings) i see:

Measurement Category	Working Voltage	Transient Voltage	Test Source (Impedance)
CAT I	300 V	1500 V	30 Ohms
CAT II	300 V	2500 V	12 Ohms

Joe: roughly, what physical size of resistors would you expect to see at the front end to meet even the 1500v (cat I) requirements? both as a single resistor, and as a string of SMD resistors.


cheers,
rob   :-)

[Fungus]

"Wear ANSI approved goggles when replacing the battery"? 

[joeqsmith]

I have never designed a handheld meter to meet these safety standards and have no idea what is required.   Worse, the manufactures don't seem to agree what the requirements are.   If that's not bad enough, I question if the "independent" test house monopoly even understands the requirements and will provide unbiased data. 

On the plus side, CAT I is a very low energy environment and the risk compared to higher ratings will be lower, assuming the person's education remains constant. 

[Fungus]

As far as your thoughts on 2000 count meters should all handle 2kV.  I guess then the UT61E at 20k counts should handle 20kV and the 300k count GMW should handle 300,000 volts?

I never said "all meters", or that it was related to counts. It just seemed odd that a 2000 count meter with a 2000V range would stop at 1100V, not 1000V.

If the Uni-T has a 20kV range then it should measure uo to 20kV. I'm betting it doesn't have a range that high though. I'd guess the highest range will be 2kV and it probably displays "OL" if you go past 1kV.

I don't own a Uni-T though or have any gadgets that will generate 1kV-2kV in a controllable manner.

[joeqsmith]

As far as your thoughts on 2000 count meters should all handle 2kV.  I guess then the UT61E at 20k counts should handle 20kV and the 300k count GMW should handle 300,000 volts?

I never said "all meters", or that it was related to counts.  It just seemed odd that a 2000 count meter with a 2000V range would stop at 1100V, not 1000V.

Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V."   There was no mention of range until now.    Still, on the back of the meter it states "5. Read the manual before use.".  You seem to have been missed this as there is no mention of a 2kV range. 

[joeqsmith]

I don't own a Uni-T though or have any gadgets that will generate 1kV-2kV in a controllable manner.

In your case, I wouldn't be too concerned about a particular meter's ability to display or survive to these levels then.   Personally,  I use a divider rather than attempting to measure voltages outside the range of the meter.   Still, I have damaged meters before making such low voltage measurement directly.   It's a sinking feeling to watch your expensive Fluke go belly up because of a weak front end design.

Video showing an old and new revision of the DT830 being exposed to 2kV.  Double the range of the older and 4X the range of the newest.   

https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg4829636/#msg4829636

[Fungus]

Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V."   There was no mention of range until now.    Still, on the back of the meter it states "5. Read the manual before use.".  You seem to have been missed this as there is no mention of a 2kV range.

Right... but then you posted a picture of a "250V" meter happily displaying 1100V:


I was just wondering where it stops measuring, it seems like a reasonable question to me.

It's a 2000 count meter so 2000V seems like a possible limit.

(unless it freaks out earlier)

[Gyro]

Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V."   There was no mention of range until now.    Still, on the back of the meter it states "5. Read the manual before use.".  You seem to have been missed this as there is no mention of a 2kV range.

Right... but then you posted a picture of a "250V" meter happily displaying 1100V:


I was just wondering where it stops measuring, it seems like a reasonable question to me.

It's a 2000 count meter so 2000V seems like a possible limit.

(unless it freaks out earlier)

These 3 1/2 digit dmms are all based on clones of the Intersil ICL7106, which has been around for decades. The chip basically has a +/-200mV input and display capability which you scale with voltage divider networks for the desired ranges. There is no intelligence in there - there are no dedicated pins for overrange, to enfoce a reading limit etc. The only way to decode the display values going to the display would be a bunch of XOR gates monitoring the LCD segment and backplane drives.

There is no way to limit the display at 250V, it will carry on displaying up to the 2000 digit reading if nothing on the board breaks down first (which it does). The manufacturers have cost reduced the meters to the point where they can't take anything like the maximum display reading without breaking down, and semsibly provided indications on the range switch and warning label. This isn't restricted to 3 1/2 cheapies, many dmms would probably display 2kV, 4kV, or 6kV (depending on IC display counts) but are limited to 1kV on the front panel labelling, instructions, and internal protection / breakdown.

There are two alternatives for the manufacturer. Either delete the 250V range altogether and provide a the maximum range at 200V, or provide the higher range and clearly indicate that it is rated for 250V max (as they have done). I know which alternative most buyers would prefer - and so is what they sell.

[joeqsmith]

Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V."   There was no mention of range until now.    Still, on the back of the meter it states "5. Read the manual before use.".  You seem to have been missed this as there is no mention of a 2kV range.

Right... but then you posted a picture of a "250V" meter happily displaying 1100V:

I was just wondering where it stops measuring, it seems like a reasonable question to me.

It's a 2000 count meter so 2000V seems like a possible limit.

(unless it freaks out earlier)

I had posted that picture prior to your asking.   The 1100ish volts isn't a magic number.  It's where that particular power supply folds back with that load.  A different power supply was required to reach the 2kV you had asked about.   The counts will have nothing to do with when the hardware fails.  All of the meters shown held up beyond their maximum ranges. 

[floobydust]

If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?

[rsjsouza]

Good testing Joe. The older versions of the M830B-type meters can take a beating but not the newer ones.

Over the years I did several tests on those meters, obviously noting the erosion in quality and materials. However, on my channel I recently tested the Hypertough TD35235J (All-Sun EM830) that is sold at Walmart stores, has third party certification and it is quite well built for the price of $12.99 on US eBay: eBay auction: #294500510119

In my lower voltage tests (up to 280Vac) I was able to damage only the 1.5 and 9V battery testers (I forgot about the load resistors). Overall, it works quite well.

[Fungus]

The counts will have nothing to do with when the hardware fails.

Obviously not.  It's more down to the components, the PCB layout, and the dirt inside it.

It might be fun to do a few tests though.

(even if it tells us nothing because every 830 has a different PCB)

All of the meters shown held up beyond their maximum ranges. 

This could maybe have been part of your robustness testing - how high will it go on the voltage range before it freaks out?

[Fungus]

If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?

It's nothing to do with voltage, it's about energy.

[floobydust]

If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?

It's nothing to do with voltage, it's about energy.

What came first- the voltage creating an electric field causing an insulation breakdown and arc, or the energy behind that arc?
I say creepage and clearance largely determine a multimeter's maximum safe ("before an arc can occur") input voltage. Spacings analysis during certification with UL/CSA, they'll ask for PCB files and go through it. The high voltage tests have the final say.
My point is to look at the DT830 spacings and the astute eye will see some tight spots. Is using this on 240VAC mains outright unsafe? A reasonable question because with a "trashy" meter the risk is good to know. I keep one (DT830) in my car and a friend wants their stove checked. Use it or not?

[Fungus]

If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?

It's nothing to do with voltage, it's about energy.

What came first- the voltage creating an electric field causing an insulation breakdown and arc, or the energy behind that arc?

That wasn't what you asked, you asked about "comfort".

Is using this on 240VAC mains outright unsafe?

I vote "no".

Proof: The amount of people who use them for that.

I keep one (DT830) in my car and a friend wants their stove checked. Use it or not?

It's as much about procedure as anything else, eg. triple-check the position of the selector and probe wires, give the probe wires a tug before starting, wear wellies, wear a glove on one hand, don't try and measure the amps.

[robert.rozee]

Is using this on 240VAC mains outright unsafe?

I vote "no".
Proof: The amount of people who use them for that.
[...]
It's as much about procedure as anything else, eg. triple-check the position of the selector and probe wires, give the probe wires a tug before starting, wear wellies, wear a glove on one hand, don't try and measure the amps.

number of people, not amount

regarding the use of the multimeter you happen to have handy rather than the appropriate tool, see:
https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash


cheers,
rob   :-)

[Fungus]

Is using this on 240VAC mains outright unsafe?

The phrase I was replying to was "outright unsafe".

I just measured my mains AC using my Big Clive meter. It said 226V and I'm alive to tell the tale. I wasn't even nervous when I did it.

https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash

So ... don't use a DT830 to measure amps on a large industrial 480V supply? Got it! 

[David Aurora]

Is using this on 240VAC mains outright unsafe?

I vote "no".
Proof: The amount of people who use them for that.
[...]
It's as much about procedure as anything else, eg. triple-check the position of the selector and probe wires, give the probe wires a tug before starting, wear wellies, wear a glove on one hand, don't try and measure the amps.

number of people, not amount

regarding the use of the multimeter you happen to have handy rather than the appropriate tool, see:
https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash


cheers,
rob   :-)

The reality of this thread is that nothing anyone can say is gonna convince this guy that his meter is anything short of amazing.

Either we're misrepresenting what he says, or any dangers of the meter can be negated by wearing gumboots, or anyone who doesn't want to risk blowing their hand off to save a few bucks is a softcock, or we don't understand how awesome having a transistor tester in our meter is, or our measurement expectations are too high/low, or you're a 1%er with a bad toupee if you use a proper meter, etc. The goalposts move for every good reason given to avoid a meter that literally costs less than a shitty pizza from Dominos. I've personally been getting a good laugh out of this trainwreck thread ever since the "secret" tip he shared on page one about using hot glue in the ends of your probes to make them better. It's kind of like watching an Ichiban Moto video, except this guy isn't in on the joke.

At the end of the day, old mate just wants a pat on the back for outwitting everyone and getting the bargain of a lifetime.

[Fungus]

Either we're misrepresenting what he says

Yep.

or any dangers of the meter can be negated by wearing gumboots

Why are you banging on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on about "safety".

Not once have I ever said this meter is suitable for high-energy work.

(in fact I've said "don't!" several times)

[David Aurora]

Either we're misrepresenting what he says

Yep.

or any dangers of the meter can be negated by wearing gumboots

Why are you banging on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on about "safety".

Not once have I ever said this meter is suitable for high-energy work.

(in fact I've said "don't!" several times)

Is using this on 240VAC mains outright unsafe?

The phrase I was replying to was "outright unsafe".

I just measured my mains AC using my Big Clive meter. It said 226V and I'm alive to tell the tale. I wasn't even nervous when I did it.

https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash

So ... don't use a DT830 to measure amps on a large industrial 480V supply? Got it! 

Another post, another sidestep. Yawn.

The reason I and others have banged on about safety is because stupid people read stupid advice on the internet and then go do stupid things. This thread is full of such advice. You keep banging on about how these things work just fine at high voltages, then when you get called out you backtrack and claim you never said they were suitable for it. One minute you're saying "Don't do it", the next you're saying you did anyway. Some noob could easily take your bravado as gospel and go probing mains using the wrong terminals or mode and get a free pass to destination fucked. They could even do it correctly, cop a surge and still get that ticket. They could just as easily (and this is the key here) probe something that SHOULD be low energy but isn't due to circuit failure or mislabelling, and be completely unprepared for the shitstorm that rains down.

If you love these things for testing 9V batteries and measuring resistors then cool, that's great. But once you start sprinkling disclaimers about your safety advice being "to appease thread nannies" and telling stories about using these meters for things people shouldn't, you're making a clear inference that these ARE in fact OK to use in potentially lethal situations.

[Fungus]

You keep banging on about how these things work just fine at high voltages, then when you get called out you backtrack and claim you never said they were suitable for it.

Rubbish.

I said they were suitable for high voltage, and I stand by that. Pictures have been posted of a worse meter than this measuring 1100V in somebody's hand.

(I notice you don't go after joe...)

I also said they weren't suitable for high energy. If you can't understand the difference between the two then you're in no position to lecture anybody on safety.

This meter is CAT I 500V rated. I think that's a correct rating and said so in the very first post, anything else is just your imagination.

End of.