EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: 001 on September 23, 2018, 11:21:08 pm
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Is some new version here?
(https://i.ebayimg.com/images/g/XEoAAOSwsddbdCHd/s-l1600.jpg)
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Looks like a new one.
No MIN/MAX/REL?
Ohms/diode/continuity/capacitance all crammed into a single range? That doesn't sound like much fun.
I'll stick with the 860B+.
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From the display it looks like it does have MIN/MAX and REL
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From the display it looks like it does have MIN/MAX and REL
That doesn't mean anything. They use the same display in all their meters.
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This looks sort of like a redesigned ZT102, with a uA range. I looked at the current Zotek models and none of them seem to match exactly.
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This looks sort of like a redesigned ZT102, with a uA range. I looked at the current Zotek models and none of them seem to match exactly.
WHY?
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I have been looking at the meter (Review will show up at a later date), but I will post a warning here:
mA range is protected with a 200mA PTC, not very smart for a 600mA range.
10A range is unfused, even though the front says fused.
The enclosure says it uses a 9V battery, but it uses 2xAAA.
(https://lygte-info.dk/pic/Aneng/AN882B/DSC_2995.jpg)
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WTF :o almost empty case.
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I have been looking at the meter (Review will show up at a later date), but I will post a warning here:
mA range is protected with a 200mA PTC, not very smart for a 600mA range.
Not necessarily bad for protection (it will heat up much faster if it's underrated) but it will cause big burden voltages as you go higher.
10A range is unfused, even though the front says fused.
The fuses are the probe cables.
Joking aside: This is not good. I guess even ANENG has trouble producing meters at this price. This is only slightly better than an 830B.
The bad part is that it could damage their reputation for $20 meters (which are quite good).
WTF :o almost empty case.
Not looked inside many multimeters...? :popcorn:
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I have been looking at the meter (Review will show up at a later date), but I will post a warning here:
mA range is protected with a 200mA PTC, not very smart for a 600mA range.
Not necessarily bad for protection (it will heat up much faster if it's underrated) but it will cause big burden voltages as you go higher.
It will heat up too fast to measure 600mA
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Not looked inside many multimeters...? :popcorn:
About 10 Different multimeters :-DD
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Not looked inside many multimeters...? :popcorn:
About 10 Different multimeters :-DD
You are are interested in the inside of multimeters you can just check my review list:
https://lygte-info.dk/info/DMMReviews.html
It is more than 70 multimeters now, both cheap and expensive.
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I have visited your website often, nice work :-+
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It will heat up too fast to measure 600mA
It should take several seconds to heat up, but... yeah. Not good for a multimeter. You couldn't leave it connected while you're working on something. :--
Maybe you can measure the time needed to heat up and/or plot a graph of burden voltage against time as part of your review.
(also: don't PTCs have a limited number of cycles before they die?)
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Is some new version here?
It certainly looks so. Although... Yawn. Pretty boring meter IMO.
WTF :o almost empty case.
It may be the Harbor Freight (https://www.eevblog.com/forum/reviews/harbor-freight-cen-tech-90899-small-teardown/) effect...
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Is some new version here?
It certainly looks so. Although... Yawn. Pretty boring meter IMO.
WTF :o almost empty case.
It may be the Harbor Freight (https://www.eevblog.com/forum/reviews/harbor-freight-cen-tech-90899-small-teardown/) effect...
Spot on :-DD
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It will heat up too fast to measure 600mA
It should take several seconds to heat up, but... yeah. Not good for a multimeter. You couldn't leave it connected while you're working on something. :--
Maybe you can measure the time needed to heat up and/or plot a graph of burden voltage against time as part of your review.
(also: don't PTCs have a limited number of cycles before they die?)
Fairly easy to do:
(http://lygte-info.dk/pic/Aneng/AN882B/400mA.png)
First one is 400mA
(http://lygte-info.dk/pic/Aneng/AN882B/600mA.png)
Second one is 600mA
In addition to a high burden voltage you also got a strict time limit.
I would not worry about any limit on PTC cycles, it depends on how serious out overload it and I doubt it would have much affect with low voltage, maybe mains voltage would add some wear.
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There's plenty of room in there for decent fuses, but oops it's under the display...
PTC fuses fatigue after the first few trips, their holding current drops quite a bit. It would be good to trip it say 5 times and then do the test. I wonder about its voltage rating, only telecom PTC's good to high voltage but they are much larger than this one. Think about the holding current+voltage and all the heat generated.
What is the pushbutton switch (pads) for on the backside? CAL mode perhaps.
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PTC fuses fatigue after the first few trips, their holding current drops quite a bit. It would be good to trip it say 5 times and then do the test. I wonder about its voltage rating, only telecom PTC's good to high voltage but they are much larger than this one. Think about the holding current+voltage and all the heat generated.
PTC are sometimes used as temperature sensors, the change will depend on how hard they are over driven and what they are designed for.
I doubt a small over current will add much wear to the PTC.
What is the pushbutton switch (pads) for on the backside? CAL mode perhaps.
I would expect it to be a button that is used together with one or two of the front buttons to activate calibration, maybe the REL or RANGE button. As you can tell I did not check it.
My reviews are not about uncovering all the secrets in a multimeter (or any product), this is much better done in a thread here. I am satisfied if I can describe the behaviour of the meter in a way that means people buying it knows what they get.
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Second one is 600mA
You get over two seconds to take the reading - plenty of time! :palm:
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PS: And how long to cool down again?
eg. If you switch to 10mA, how long before the burden voltage returns close to zero?
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Second one is 600mA
You get over two seconds to take the reading - plenty of time! :palm:
Facepalm indeed... somehow I think that Zotek (Aneng's ODM) is starting to randomly throw PTCs around the board to see what is EEVBlog's forum folks think of that. If something sticks, then it must be good. First it was the puny PTC near the main IC (AN8008, 8009, 860, 870) and now is on the mA range. What's next? :scared:
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PTC fuses fatigue after the first few trips, their holding current drops quite a bit. It would be good to trip it say 5 times and then do the test. I wonder about its voltage rating, only telecom PTC's good to high voltage but they are much larger than this one. Think about the holding current+voltage and all the heat generated.
PTC are sometimes used as temperature sensors, the change will depend on how hard they are over driven and what they are designed for.
I doubt a small over current will add much wear to the PTC.
"When there is an overload condition, the polymer heats up internally from I2R heating. When the polymer heats up to approximately 100-125°C, its molecular structure changes from semi-crystalline to amorphous. This causes a macroscopic expansion, which breaks the conductive paths. When the conductive paths are broken there is a large increase in resistance - typically several orders of magnitude. At this point, the device is in the “tripped state”. Upon cooling, the polymer reforms to its semicrystallized state and the conductive pathways are reestablished. However, when the polymer recrystallizes it does not return immediately to the same base resistance. It does not compact as tightly as when it was pre-tripped, and therefore the post trip resistance is typically 50 % higher then the initial resistance. Note the post trip resistance increase is not a cumulative effect; additional tripping will not cause increases in resistance in excess of the first trip."
https://www.bourns.com/resources/technical-library/library-documents/multifuse-pptc-resettable-fuses-technical-library (https://www.bourns.com/resources/technical-library/library-documents/multifuse-pptc-resettable-fuses-technical-library)
I did extensive testing on PTC fuses and found they change after the first (few) trips, so I had to factor that into my designs.
Here, the 600mA trip might go to 500mA and be very annoying.
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PS: And how long to cool down again?
eg. If you switch to 10mA, how long before the burden voltage returns close to zero?
About 10 seconds, at least if I switches to 10mA fairly fast.
(http://lygte-info.dk/pic/Aneng/AN882B/600-10mA.png)
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Facepalm indeed... somehow I think that Zotek (Aneng's ODM) is starting to randomly throw PTCs around the board to see what is EEVBlog's forum folks think of that. If something sticks, then it must be good. First it was the puny PTC near the main IC (AN8008, 8009, 860, 870) and now is on the mA range. What's next? :scared:
It is nothing new with PTC's as current fuses, Mastech has been using it for a long time and I have also seen it in some pocket meters, but usual the PTC is selected to match the current range.
The small PTC's in meters works fine and will usual handle mains voltage on ohms range, but not much more (Like CAT over voltage). Most cheap meters also has a small 900kOhm resistor that would have trouble with much above mains voltage.