A look at the Uni-T UT210E

[bitseeker]

Yep.

AliExpress: US$33-34.

[hgg]

My device had no pull-up resistor - took me about three hours, with attentive observation and trying to understand - what is not right.  I soldered an adapter for usbasp <-> clip (used SMD pull-up resistors , so to small to see).  So clip on a chip, selector switch in something other than OFF, and you can be read / write.

Did you use the USBasp programmer for this?
Can the USBTinyISP programmer be used as well or is it compatible only with ATMEL AVR chips?

[TheAmmoniacal]

Haven't read the whole thread (so sorry if this has been asked previously), how easily does it pick up interference from nearby cables for DC current? Would you at all be able to get a reasonable reading from one of the wires in a ribbon cable? If you have one cable through the clamp and one just outside - but next to it - do you get an additive reading?

Some testing for this would be very much appreciated.

[macboy]

Haven't read the whole thread (so sorry if this has been asked previously), how easily does it pick up interference from nearby cables for DC current? Would you at all be able to get a reasonable reading from one of the wires in a ribbon cable? If you have one cable through the clamp and one just outside - but next to it - do you get an additive reading?

Some testing for this would be very much appreciated.

No problem taking readings with the return wire nearby. Conductors outside the clamp, even touching it, do not affect the reading.

[TheAmmoniacal]

How do they shield the hall effect sensor?

[joeqsmith]

Do you think if you hold a DC clamp right next to a wire instead of placing the wire through it, it will read the same current?   

Haven't read the whole thread (so sorry if this has been asked previously), how easily does it pick up interference from nearby cables for DC current? Would you at all be able to get a reasonable reading from one of the wires in a ribbon cable? If you have one cable through the clamp and one just outside - but next to it - do you get an additive reading?

Some testing for this would be very much appreciated.

[TheAmmoniacal]

No, but I do (did?) think it would /affect/ the reading.

[Maxlor]

I tested it just now. I put 1.5A through the clamp, and placed a wire carrying 0.5A in various positions around the clamp. I could make the reading change by approx +- 5mA. Having the second wire pass by the clamp in a straight line would show next to no effect, having it go in a half circle around the clamp affects the reading by a couple of mA.

[TheAmmoniacal]

That is impressive, thanks!

Anyone know how they achieve this?

A conductor should induce a magnetic field in the core of the clamp indiscriminate of being in the loop or outside. Are they somehow using the radial nature of the magnetic field being induced?

[TheAmmoniacal]

A conductor should induce a magnetic field in the core of the clamp indiscriminate of being in the loop or outside.

Could you explain why?
[/quote

Nope, I'm wrong 

[timofonic]

A conductor should induce a magnetic field in the core of the clamp indiscriminate of being in the loop or outside.

Could you explain why?
[/quote

Nope, I'm wrong 

Why are you wrong?

[Maxlor]

That is impressive, thanks!

Anyone know how they achieve this?

A conductor should induce a magnetic field in the core of the clamp indiscriminate of being in the loop or outside. Are they somehow using the radial nature of the magnetic field being induced?

Actually it's about what you'd expect, and roughly the same range as the errors you get when you just rotate the meter and thus change its exposure to ambient magnetic fields. There won't be anything in the meter to counteract these types of fields specifically.

As for the discrimination: maybe consider this: http://www.electronics-tutorials.ws/electromagnetism/mag8.gif
A conductor passing through the clamp creates circular magnetic flux in the clamp's ferrite, whereas when the conductor is outside the clamp, the flux isn't circular but very roughly unidirectional, which a much smaller total flux value.

Eh, at least that's how I imagine it working, but I admit it's been a while since the physics lecture that discussed this.

[obd.tech]

Just wondered how much drift and stability this little tool has on the 2A DC setting?

I just found that there is a brother model called the UT210'D' that has an AC/DC amp range to 20/200Amps with a resolution of 10mA. Also comes with frequency and temperature readings.
Anyone used it or can comment on what's likely to be more real world usable for testing low current draw for vehicle battery drains etc 

[Maxlor]

Just wondered how much drift and stability this little tool has on the 2A DC setting?

This has been answered in the very first post in this thread, and several later ones as well. Or are you asking about anything other than very short term drift? If so, realize that this is not a precision instrument, it can drift a fair amount and not get anywhere near its accuracy boundaries.

I just found that there is a brother model called the UT210'D' that has an AC/DC amp range to 20/200Amps with a resolution of 10mA. Also comes with frequency and temperature readings.
Anyone used it or can comment on what's likely to be more real world usable for testing low current draw for vehicle battery drains etc

I don't see the point in the D model. 1mA resolution is a lot more useful than just twice the max range. Or in other words, if I didn't need 1mA resolution, I'd pick one of the many clamps that go into several hundred to 1000 Amps.

Battery drain and charge currents in vehicles is usually on the order of a few amps, so you'd use the 20A mode for that most of the time. So either device would work. Don't leave the clamp on when starting the engine though as the current will be in the several hundreds of A; if I understand Joe's post earlier in this thread correctly, this overcurrent might magnetize the ferrite.

The extra features don't matter to me much, I have them in other, better multimeters. Imo they might as well have simplified the device and left out the jacks and associated modes. We like this meter because it's pretty much the only clamp at this price point that measures high res DC current; for anything other than measuring current other meters are easier to use, more accurate and generally better.

[joeqsmith]

I think obd.tech is referring when the car goes into standby where it can draw well below 50mA.   This it the whole reason I did not test this meter to destruction as I actually use if for this test.   It works very well for it.  You just need to zero it out before you take your reading.  Beats pulling the cable.

I too have no need for any features beyond the clamp and if it could not resolve sub 50mA, really would not have a use for it.   

I have a few of these now and I have caused them to take a set (become magnetized).  If it gets bad enough, you will need to make yourself a degauss tool for it.  I am not sure at what current this will happen.   My welder did a number on it and so did a magnet.     I have always been able to recover them.

Just wondered how much drift and stability this little tool has on the 2A DC setting?

This has been answered in the very first post in this thread, and several later ones as well. Or are you asking about anything other than very short term drift? If so, realize that this is not a precision instrument, it can drift a fair amount and not get anywhere near its accuracy boundaries.

I just found that there is a brother model called the UT210'D' that has an AC/DC amp range to 20/200Amps with a resolution of 10mA. Also comes with frequency and temperature readings.
Anyone used it or can comment on what's likely to be more real world usable for testing low current draw for vehicle battery drains etc

I don't see the point in the D model. 1mA resolution is a lot more useful than just twice the max range. Or in other words, if I didn't need 1mA resolution, I'd pick one of the many clamps that go into several hundred to 1000 Amps.

Battery drain and charge currents in vehicles is usually on the order of a few amps, so you'd use the 20A mode for that most of the time. So either device would work. Don't leave the clamp on when starting the engine though as the current will be in the several hundreds of A; if I understand Joe's post earlier in this thread correctly, this overcurrent might magnetize the ferrite.

The extra features don't matter to me much, I have them in other, better multimeters. Imo they might as well have simplified the device and left out the jacks and associated modes. We like this meter because it's pretty much the only clamp at this price point that measures high res DC current; for anything other than measuring current other meters are easier to use, more accurate and generally better.

[obd.tech]

Thanks Guy's,
understand what your your saying about what it does for the price point.
I was wondering how much zero drift different ones had (batch variation?) as my primary use for 1 would be Parasitic battery drains when cars 'shut down' , like joeqsmith commented on.
I also have tried other amp clamps and some are so variable that they are unusable with any confidence for this task, maybe i was thinking that readings in the 10mA and lower, accuracy is too much to expect in real usable workshop conditions?
My trusted 'old friend' is a Lem Heme LH630 which is pretty stable but only has a 100mA resolution, it does the job (no manual zero point  ), but a finer accuracy is always nice as long as its stable 

Have you guys any idea what limit's the UT210E will handle before this 'set' magnetism happens? Is it dependant on the setting your on? i.e. 2A and you measure 150% of this........or 150% of it's 100A maximum value (does that make sense?) Basically if you overload the hall sensor? or is it the clamp core that becomes magnetised?
If this 'set' condition happens....what is the resultant behaviour and what was your degauss tool to fix it.
Thanks Guy's 

[Maxlor]

I don't have data about batch variation, and I doubt others here have tested enough of these meters to make a statement about that with any confidence. Lacking that, your next best thing is the stated accuracy, which is 2% +- 8 counts for the 2A DC range, and 2% +- 3 counts for the other DC ranges.

Magnetizing might happen when you go above 100A, switch setting doesn't matter.

[bitwelder]

The instructions for the UT210E warn in the AC/DC current measurement section:

When measure current, unplug test pen to avoid electric shock.

I get that the accidental contact with the test leads may disturb the current clamp measurement, but is there really a risk of electric shock if somebody touches them?
What are the voltage levels induced in the instrument while using the clamp?

[obd.tech]

I don't have data about batch variation, and I doubt others here have tested enough of these meters to make a statement about that with any confidence. Lacking that, your next best thing is the stated accuracy, which is 2% +- 8 counts for the 2A DC range, and 2% +- 3 counts for the other DC ranges.

Magnetizing might happen when you go above 100A, switch setting doesn't matter.

What i was asking for was 'how many mA's do your meter's drift' to get a real world feedback from you guys, to get a picture of average/min/max variation between ones actually used.
Far better than any tech spec's IMO 

[joeqsmith]

It only needs to be stable long enough to take the reading.  I zero it, clamp it, read it, done.   I have never had a need to watch the current for a half hour while the car goes to sleep.    If there is problem (trunk light, hood light, glove box light... stuck on), current is easy to detect with it.    Of course you go putting your magnetic screw drive next to it, you are going to have problems.    Who cares about the zero point for a batch.  That's why you zero it out before you take a reading.  It's a button, you push it.   Keep in mind, this is not a unique problem for this low end DC clamp.  Having a DC offset is common.   So is having to degauss. 

As stated, the range switch has nothing to do with when the clamp becomes magnetized.  Even if you had a perfect meter where  0 ADC was 0, put it in the drawer with your magnetic screw drivers and that will solve that!   

It may be a good idea for you to read a little about how a DC clamp works.  If you magnetize the clamp, the sensor will be effected by it.  It can't tell how the clamp was magnetized.  So you get an offset with the DC Amps.   How much will depend how far you push it.   Could be several Amps or mAs.  To degauss these, I have been using a large copper coil that I have feed the probe through.   The coil is just running off the line.   

I was wondering how much zero drift different ones had (batch variation?) as my primary use for 1 would be Parasitic battery drains when cars 'shut down' , like joeqsmith commented on.

...

Have you guys any idea what limit's the UT210E will handle before this 'set' magnetism happens? Is it dependant on the setting your on? i.e. 2A and you measure 150% of this........or 150% of it's 100A maximum value (does that make sense?) Basically if you overload the hall sensor? or is it the clamp core that becomes magnetised?
If this 'set' condition happens....what is the resultant behaviour and what was your degauss tool to fix it.
Thanks Guy's 

[joeqsmith]

It's a UNI-T?  Why would you ever plug the leads into it!    

My guess is their concern is you have the leads attached to something sitting at some potential and now you place the clamp over another circuit that having a much different potential, the probe could arc over. 

The instructions for the UT210E warn in the AC/DC current measurement section:

When measure current, unplug test pen to avoid electric shock.

I get that the accidental contact with the test leads may disturb the current clamp measurement, but is there really a risk of electric shock if somebody touches them?
What are the voltage levels induced in the instrument while using the clamp?

[obd.tech]

Thanks joe  & Maxlor but i think you misunderstood what i was trying to establish?
Car trunk lights etc 'stuck on' is easy stuff that my Lem clamp will find easy even with 100mA resolution.
I'm after confirmation that this UT210E is stable for periods of time when watching for small intermittent active drains from body modules etc switching.
Some cars can take upto an hour to shut down (tho i haven't yet found any)

If this meter is up and down like a fiddlers elbow (like a few i've tested) it is of no help 

What i'm asking you guys is can you tell me by how much does 'YOUR' UT210E drift over 10/20/30 minutes.
Hope you understand my question now 

[Maxlor]

If you set it down in 2mA mode and watch the meter without touching it, expect it to drift beyond 10mA in about a minute. I haven't done any testing beyond that, but I've seen offsets of a few hundred mA while setting up, just moving the meter around. So I don't expect prolongued measurements to be very useful; zeroing is an essential part of the measurement. If you need to track power consumption ever time, you should use this procedure: zero, clamp on, read value, clamp off, repeat after a couple of minutes.

Mind you, this applies to DC measurements, which are difficult to do with a clamp because of $physics. Any DC clamp will have the same problem. It's much easier to get good AC readings

[timofonic]

So a clamp for DC= useless?

[joeqsmith]

So a clamp for DC= useless?

   
I take it when you wrote "watching for small intermittent active drains" this is some sort of transient condition.   Your plan is to sit and watch it for a half hour to see if you can detect an this intermittent draw?   I'm way too lazy for that even if it were not under the hood of a car!   One blink of the eye and you lost your sample.    

I am not sure what you require for a sample rate or what sort of change in current you are trying to detect.  That fact you were looking at a clamp with a 10mA res tells me you're looking for some big shifts.   The fact your looking at a meter to do it and feel you can catch it with your eyes tells me it is very slow.   

What I could do if you are interested is I have modified a UT210E to provide an analog output.   If you ignore the temperature changes in the room, the changes I made to the clamp, the drift of my meter, etc.   Then you would need to consider that the drift of the clamps ADC would not be considered.    I could get you a fairly good idea.  I would run no current through the probe, leave it setup where it would not be disturbed mechanically.    Then just log it for a half hour or so at say once a second.  From this I could give you the standard deviation, mean, min, max or what ever else you are looking for.   

Thanks joe  & Maxlor but i think you misunderstood what i was trying to establish?
Car trunk lights etc 'stuck on' is easy stuff that my Lem clamp will find easy even with 100mA resolution.
I'm after confirmation that this UT210E is stable for periods of time when watching for small intermittent active drains from body modules etc switching.
Some cars can take upto an hour to shut down (tho i haven't yet found any)

If this meter is up and down like a fiddlers elbow (like a few i've tested) it is of no help 

What i'm asking you guys is can you tell me by how much does 'YOUR' UT210E drift over 10/20/30 minutes.
Hope you understand my question now