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

[joeqsmith]

...I wonder if Flukes protect people from that?

Don't most of the higher end meters I show have a dead stop, far away from the shunts?   

[Fungus]

Ceramic fuses? 

Yep. And 500V rated!

[Fungus]

"Fuck you I like them" is a perfectly good reason too.

Let's go with that then. 

[EEVblog]

Hell, "Fuck you I like them" is a perfectly good reason too. I was just trying to understand the attraction.

Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.

[AndyBeez]

I wonder if that trashy meter carbonates?

[M0HZH]

I don't get it- why do people buy stuff like this?

I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal 

I bought one when I was a kid and couldn't afford anyting else.
I bought one when I needed to check something and I was 2 hours away from my other meters.
I bought one for a basic tool kit that stays at a remote radio site (runs on solar, 2h hike from the closest road) just in case someone without tools needs to do a quick check-up

Plenty other reasons why you would by a cheap disposable meter.

[EEVblog]

Plenty other reasons why you would by a cheap disposable meter.

Maybe, but when you can get a quite decent $20 class meter these days, I'm not seeing much of a point.

[Fungus]

Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.

Clive doesn't hold back on the tech stuff, he does a lot of good reverse engineering and explanation of the circuits he finds. inside those trashy things. Some of them are quite ingenious. Making things for $5 isn't easy.

(and others are dangerous and he always explains why... it's all stuff worth knowing)

[Fungus]

Maybe, but when you can get a quite decent $20 class meter these days, I'm not seeing much of a point.

The point is that now we know there's $4 meters that can do it too.

(so long as all you need is basic features)

PS: Don't you make videos along the lines of "What's the cheapest possible microcontroller?" Why should we struggle to use barely-documented, unknown Chinese chips in out projects when we can get mainstream AVR chips for under $1?

[robert.rozee]

Plenty other reasons why you would by a cheap disposable meter.

Maybe, but when you can get a quite decent $20 class meter these days, I'm not seeing much of a point.

it depends if you have $20 in your wallet, or only $4.

my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters. issues of minimum creepage and clearance distances. the likes of Fluke take these quite seriously, the chinese makers of the cheaper brands less so. the reality is that (adherence to) these distances are likely not going to be put to the test by the vast majority of users; but on the odd occasion the some users may find themselves less lucky.

it seems to be that the cost of improving creepage and clearance distances should be quite minimal. either that, or ensure the multimeter tops out at a suitably low voltage (<50v RMS). see: https://en.wikipedia.org/wiki/Low_voltage


cheers,
rob   :-)

[Fungus]

my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters.

With the dial and leads in the correct position? I'd put my money on "not much apart from displaying the voltage on screen".

Even with the meter in this thread I'd go with "not much".

I haven't traced the circuit out but it appears to be made by a company that takes things seriously. I'd say the only reason they rate it for mains AC is that the lowest applicable rating includes voltage surges of 2500V+ which would be too much for it.

Measuring 230V AC though? Probably OK, although I wouldn't advise anybody to do it - surges happen!

Not everybody goes near mains electricity though and it's perfectly OK to buy one of those meters if you don't.

If you work on mains AC all day long? Get a suitable meter.

PS: Can you put your hand on your heart and swear you always wear gloves, etc. when poking at mains AC with your Fluke?

[robert.rozee]

my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters.

I'd say the only reason they rate it for mains AC is that the lowest applicable rating includes voltage surges of 2500V+ which would be too much for it. Measuring 230V AC though? Probably OK, although I wouldn't advise anybody to do it - surges happen!

not quite sure what you've written is entirely clear, but i think you're asserting that for measuring 230v AC the meter should have a 2.5kv surge rating. with this, i would broadly agree. there are many standards from around the world, but i would agree that being able to withstand a 2.5kv surge is a reasonable compromise for measuring domestic AC.

but are you also saying that it is OK for a piece of test equipment with a scale calibrated up to 250v or more, sold as being suitable for the purchaser to measure domestic AC mains, to not be able to withstand a 2.5kv surge? if this is what you are saying, then, well, why do we even bother having these safety standards?!

i think we all agree that DT-830 style multimeters are not suitable for measuring domestic AC mains voltages. i am just going one step further to suggest that manufacturers and retailers of such multimeters should be held accountable for selling a product that does not comply with the relevant safety standards. ie, farnell should not sell such products, repco and bunnings (or walmart or ASDA) should not sell such products, ebay should not allow such products to be listed on their site.

as an alternative, it should be fine for anyone to sell products that either comply with the relevant safety standards (the Fluke 101 provides a good example), or that are constrained to be usable only within safe limits - that is <50v RMS or thereabouts. either step would not seriously impact the manufacturing cost: remove the 500/1000/2kv ranges, limit the display of 200v ranges so that the multimeter displays an 'over-range' for anything over 72v AC/DC, move current ranges to a separate uA/mA input socket, redesign PCB layout and component choices to meet minimum creepage and clearance distances.

after all, if i were to set up shop selling pairs of rubber kitchen gloves marked in big letters across each glove as "250v safe", how long would i be allowed to stay in business?

PS: Can you put your hand on your heart and swear you always wear gloves, etc. when poking at mains AC with your Fluke?

i take reasonable precautions around mains AC voltages. if i have any doubts about what i am doing, i STOP. that is simple common sense, coincidentally one of the least common commodities in this universe.


cheers,
rob   :-)

[Fungus]

but i think you're asserting that for measuring 230v AC the meter should have a 2.5kv surge rating.

It's not an "assertion".

It's the requirement for a meter to be labelled "CAT II 300V", as defined by industry experts.

but are you also saying that it is OK for a piece of test equipment with a scale calibrated up to 250v or more, sold as being suitable for the purchaser to measure domestic AC mains, to not be able to withstand a 2.5kv surge? if this is what you are saying, then...

I'm not saying that at all.

What I'm saying is that I would carefully use this meter to measure 230V mains in a pinch, if there was nothing better around.

Car analogy: Using this meter to measure mains is like driving without a seatbelt. You won't instantly die if you do it, you can probably do it for years and get away with it. I don't recommend it though and I always wear mine.

Careful driving isn't a substitute so that's why I added "If you work on mains AC all day long? Get a suitable meter.".


PS: This meter clearly says "CAT I" on the front so it is not being sold as "suitable for the purchaser to measure domestic AC mains".

[robert.rozee]

PS: This meter clearly says "CAT I" on the front so it is not being sold as "suitable for the purchaser to measure domestic AC mains"

the DO3047 has 500v written SIX times on the front of it, including the two ranges (AC and DC) labelled 500. an average reasonable person (as defined in law) would be hard pushed to not assume it was safe for making measurements up to 500 volts. the "cat I" text occurs just once. i see that "CAT I describes secondary circuits not intended to be connected to the mains electricity supply" (https://www.flir.com/discover/professional-tools/what-do-cat-ratings-mean/). off the top of my head, i can not think where the average person might today encounter such a defined source. in times gone by, perhaps a battery-powered fluorescent lamp? but today, no.

Car analogy: Using this meter to measure mains is like driving without a seatbelt. You won't instantly die if you do it, you can probably do it for years and get away with it

it is a poor analogy, "About 90 people are killed every year on New Zealand roads because they weren't wearing a seatbelt" (https://www.nzta.govt.nz/about-us/about-waka-kotahi-nz-transport-agency/annual-report-2018-19/safety/). our front-line police officers have the unpleasant task of attending to those 90 dead, mangled bodies. extrapolating worldwide, that is around 144,000 dead, mangled bodies.

[Bud]

Hell, "Fuck you I like them" is a perfectly good reason too. I was just trying to understand the attraction.

Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.

Yeah, I am not sure if the guy has ever used an oscilloscope. Or even knows what it is.

[AndyBeez]

There is a justifiable real world use case for trashy meters: A school science lab or engineering department requires meters that can be used, abused, destroyed and stolen by pupils, whilst keeping inside the school's diminished science/engineering budget. [ As the school prefers to spend all of its funds on a fully equipped sport gym, next year's budget will be even slimmer. Which will be blown on portable oscilloscopes. ] Chances are, the smart EE students will already have a Fluke or EEVBlog meter at home.

As for the price of these meters, put your production engineering hard-hats on for a moment. Could as a business you design, manufacture, promote and distribute these meters for their western market price point? Very unlikely.

[Fungus]

an average reasonable person (as defined in law) would be hard pushed to not assume it was safe for making measurements up to 500 volts.

An "average person" has no business poking around inside mains distribution panels. It might even be illegal.

Even Dave doesn't do it. He calls in an electrician in the videos where he's connecting up his solar panels, etc.

I assume all electricians:
a) Are aware of what a CAT rating is
b) Would laugh if they were given this meter to work with

it is a poor analogy, "About 90 people are killed every year on New Zealand roads because they weren't wearing a seatbelt"

It's a perfect analogy, you just forgot to contrast with "how many people didn't?"

According to this page: 91,000 people were fined in NZ for not wearing a seatbelt.

https://www.stuff.co.nz/motoring/122306446/traffic-fines-have-cost-kiwis-more-than-272-million

(nb. that's just the ones who were caught/fined - the real number will be much, much higher)

[Fungus]

The manual that comes with this meter is surprisingly specific about overload protection on each range:





Edit: I'm not sure why it says the 5A range has a 250V fuse, the one inside the meter definitely has "500V" stamped on it.


Maybe they decided to upgrade the fuse to match the other one after the manual was printed - avoid confusion by having them both the same.

[robert.rozee]

with just a little photo editing, here is a much more suitable version:



note that apart from removing ranges, a small electrical modification would be required so that above 75v an over range is displayed - the continuity buzzer could also be pulsed as an extra warning.


cheers,
rob   :-)

[joeqsmith]

... , i can not think where the average person might today encounter such a defined source. in times gone by, perhaps a battery-powered fluorescent lamp? but today, no.

From the link provided:

CAT I describes secondary circuits not intended to be connected to the mains electricity supply, such as electronics, including a typical laptop PC, and circuits powered by regulated low voltage sources.

I wouldn't consider people involved with this forum being average.  I'm sure there are a few of us working with electronics in excess of 500V.  I would have no problem using even the free HF meter to measure kV levels as long as the energy is low enough.   

[Fungus]

I would have no problem using even the free HF meter to measure kV levels as long as the energy is low enough.

Yep. That's another reason to own them.

I used to use them to monitor voltages when I was in my "Can I make big sparks?" phase (we've all been there...)

They measure 1000V, no problem. Just don't hold them in your hand while you do it.

[joeqsmith]

They measure 1000V, no problem. Just don't hold them in your hand while you do it.

Why not?   

Here are two free HF meters.  Newer style on the left is now marked 250VDC compared with the original 1kV marking.   Also shown with me holding the new low voltage meter in parallel with the Brymen BM789 with 1kV applied, no gloves.    I'm sure there are a few people who would consider this a very unsafe practice but as I said, it comes down to the energy available and your level of education.   

[Fungus]

They measure 1000V, no problem. Just don't hold them in your hand while you do it.

Why not?   

As a disclaimer to the thread nannies.

Here are two free HF meters.  Newer style on the left is now marked 250VDC compared with the original 1kV marking.

But they still measure/display 1kV, right?

[joeqsmith]

They measure 1000V, no problem. Just don't hold them in your hand while you do it.

Why not?   

As a disclaimer to the thread nannies.

It's better to educate with facts than spread fairy tails.   My grill starter can put out Amps at several kVs.  It would even damage this meter.  But I would have no problem surviving a direct pulse from it..   

Here are two free HF meters.  Newer style on the left is now marked 250VDC compared with the original 1kV marking.

But they still measure/display 1kV, right?

I guess posting it was a kV and having the three meters reading a kV still left you with that question.   YES they can still display 1kV.   And if someone was thinking that the supplied leads were not safe to use under these conditions, I beg to differ.   

If you wanted to promote safe practices, mention the one hand rule.

[Fungus]

As a disclaimer to the thread nannies.

It's better to educate with facts than spread fairy tails. 

It's not that, I just don't want to sit through another ten posts on the subject of "safety!!"

Is there anybody here who hasn't been zapped by tens of thousands of volts? I doubt it.

eg. When getting out of a car. After walking on a nylon carpet then touching a door knob.