Products > Test Equipment
A look at the Uni-T UT210E
mgruber:
Thank you for your fast response to a newbie.
I have a pen with a round-shaped neodym magnet glued to one end, which I usually use to pick up bolts from tight spots.
So when I put this into my drill, do I need to face the magnet opposed to the + or - side of the meter clamp?
And do I need to have the pen spinning by the drill or...?
I know these question are more than embarassing for someone who has learned about magnetism at school, but decades have passed. :'(
Edit: I forgot that I also have one of those magnetic parts tray cups, where you put nuts and bolts in, in case it would be easier to do with that.
Edit #2: I managed to get it down with the magnetic pen to 0.001 when I hold the meter horizontal in "panorama mode", but when I'm holding it upright/vertical the value goes up to 0.050. What did I do wrong? :(
RoGeorge:
You did nothing wrong. The instrument is so sensitive that it can sense the magnetic field of the earth, which is about 50uT.
To overcome such a good sensitivity, you need to zero the instrument in the same location and in the same position you will use it for measuring.
Hydron:
As above, this is simply a (reasonable) limitation of the design, and why it has the zero button. This may be why more manufacturers don't offer such good resolution in clamp meters - personally I am happy with the tradeoff.
The only current clamps I have seen that manage mA level resolution without this problem have a closed or very-close-to-closed magnetic circuit. An example is the classic Tektronix AC/DC current probes, which use very clever thin film hall elements (plus lapped contact surfaces for the sliding part of the magnetic circuit) and actually null the DC field with an opposing current rather than directly measure the field strength. While extremely capable, even used these cost orders of magnitude more than the UT210E.
mgruber:
I could have sworn that the value was 0.000-0.002 no matter in what direction I held it before.
Anyway: thanks to clarify that the actual measuring process isn't affected by a magnetised clamp and that zeroing before measuring is sufficient.
brainwash:
I was a bit annoyed with the slow continuity response, so, I took a look at the DTM0600 datasheet (mine has the newer chip).
By removing the 470 ohm R7 and trying different values, I was able to get the response time down a lot when R7=90k.
According to the formula in the datasheet, with a 1.5k PTC this will measure continuity up to 2.3k. The factory setting (470) measures up to 50 ohms.
This is perfectly fine for my purposes, might not be good for you. My use-case is dragging the probe over lots of pins to see which one is connected. If it bypasses some small-value resistors, it's a bonus for me. Theoretically, with 1MOhm, the maximum continuity resistance would be ~25k.
It would be nice to be able to reduce the latching time, right now it's a bit too long for my taste. Obviously the response time could also be improved by using better probes, but it won't magically go <100ms.
Edit: I've installed a 100k resistor for R7 and got ~530 ohms maximum resistance for continuity. Not sure why that's so far off from the formula.
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