Using an ARB to test meter's continuity feature - Page 1
Forum section: electronics / testgear

author: joeqsmith
author_rank: Super Contributor
timestamp: August 16, 2015, 06:01:02 pm
content: Attempted to come up with a better way to evaluate how the continuity feature compares between different meters. I am not a big fan of touching the leads together. In doing so, I learned that the UNI-T meter I have has a unique feature from the other meters I have.Sorry for the small number of meters. This is all that remains...The UNI-T was so fast a viewer recommended we have a little fun with it...

author: dadler
author_rank: Unknown
timestamp: August 16, 2015, 06:23:13 pm
content: How were you driving the continuity tester from your function generator?

author: joeqsmith
author_rank: Super Contributor
timestamp: August 16, 2015, 06:29:59 pm
content: Quote from: dadler on August 16, 2015, 06:23:13 pmStarted using an ARB with FET. Later tried driving the inputs direct which may do a better job and would be easy to replicate.

author: dadler
author_rank: Unknown
timestamp: August 16, 2015, 06:49:44 pm
content: Quote from: joeqsmith on August 16, 2015, 06:29:59 pmI'd think that driving the FET would be closer to using the continuity tester in its intended context, as the continuity current would be provided entirely by the meter itself?Have you given any thought to experimental procedures for evaluating the latching functionality of continuity testers? I can't think of an easy way myself, at least not without opening up the meters.

author: joeqsmith
author_rank: Super Contributor
timestamp: August 16, 2015, 07:30:50 pm
content: Quote from: dadler on August 16, 2015, 06:49:44 pmI think that the recovery time for the current source would be nothing and we really would be interested in the receiver side. But I am not sure if this would always be the case. Looking at the four meters I have left, I did not see a difference. (actually, I am not sure of that as I only think I looked at one meter when I started out). I was using 0-4V signal when I tried it without the FET. Maybe some of you could try this as well.I started out with just the frequency and I thought that would not be good enough because it does not give you an idea how short of a pulse the meter could detect. This is why I added the pulse width test. Between these two, you should have a very good idea how the filter works. The resistance threshold was added last. As I stated in the video, I could see reasons people would want to adjust some of these parameters. I was expecting to see all the meters have some hysteresis in the resistance as well as filtering but was surprised to see only that UNI-T had it.

author: Fungus
author_rank: Super Contributor
timestamp: August 17, 2015, 06:29:08 am
content: Quote from: joeqsmith on August 16, 2015, 07:30:50 pmAs I understand it: The point of the test is to simulate dragging the probe across a row of contacts (eg. the legs of a chip) to find continuity.By this standard the pulse width is the better test.

author: joeqsmith
author_rank: Super Contributor
timestamp: August 17, 2015, 01:23:44 pm
content: If you watch most reviews (including my own) people tend to touch them very fast. I think I mentioned about how I will pull the leads across the pins of an IC, listening for the beep. In this case, it is near 50% DC and it's all about how fast I can move the probe without the meter missing.That said, a meter may be able to detect a 0.001 second pulse for example but then hold the beeper active for say 1 seconds. Seems we really want to know both. Personally, I would enjoy seeing more technical reviews overall.One concern I have with the UNI-T I was playing with is that it is so fast it may not have enough input filtering and may give false beeps. Would be interesting to hit some of these with a little RF and see how stable they are. I was amazed how many of the meters I looked at had no shield and the ones that did it was minimal at best. I played around with a stupid little induction heater a while ago and the Mastech meter I have would whack out when it was near the coil. Just how susceptible are the meters to different fields? This is another aspect that never gets mentioned in the reviews.

author: timofonic
author_rank: Frequent Contributor
timestamp: August 17, 2015, 04:39:15 pm
content: That's interesting. I use continuity testing most of the time and my shitty and old DMM is driving me crazy.It would be very interesting to investigate about it and if other Uni-T provides such fast response. It would be nice to know the possible disadvantages and if there's as possibility to overcome them.

author: retiredcaps
author_rank: Super Contributor
timestamp: August 17, 2015, 04:57:17 pm
content: There was another old thread about speed of continuity athttps://www.eevblog.com/forum/testgear/what-is-you-ideal-continuity-tester/msg263741/#msg263741Details of how Tooms did the test are at (warning ** lots of pictures, so may be slow loading)http://www.tooms.dk/BTW, another member did an informal test and found Fluke 8024B was the quickest.

author: timofonic
author_rank: Frequent Contributor
timestamp: August 17, 2015, 09:27:26 pm
content: Quote from: retiredcaps on August 17, 2015, 04:57:17 pmMaybe I got lost, but it seems he just used Fluke DMMs. Anyway, interesting tests!

author: joeqsmith
author_rank: Super Contributor
timestamp: August 18, 2015, 01:25:07 am
content: Looks like he only looks at the min. pulse width as well. I would want a meter that can detect a short and once opened, can reset to detect the next short very fast. He does everything at 1Hz which tells me nothing about how fast I could expect to be able to move a the probe from node to node.Quote

author: timofonic
author_rank: Frequent Contributor
timestamp: August 18, 2015, 02:17:15 am
content: Quote from: joeqsmith on August 18, 2015, 01:25:07 amMe too! I'm quite bad making PCBs, but I want to improve it. I also want to detect fails at circuits, soldered by me (I'm a bad solder too, maybe i need some tools to overcome that) or for repairing.My current DMM is virtually useless. I tried other classmates DMMs (cheap too), their continuity testing was okaish but not so responsive as I wished to be (that drives me insane in SMT PCB boards), but any crap is better than mine.I have extremely limited incomes, but I want to save to get a few DMMs. I want at least one of them to have very good continuity testing.I wonder if all Uni-T DMMs features this fast continuity testing behavior or its just available on certain models. Maybe a crowsourced experiment could provide some interesting data about it

author: tautech
author_rank: Super Contributor
timestamp: August 18, 2015, 03:15:07 am
content: Joe, thanks for the vids, excellent as usual.Would you also consider enlarging on the continuity data by testing voltage and current like in this thread:https://www.eevblog.com/forum/testgear/multimeter-with-low-continuity-test-voltage/

author: joeqsmith
author_rank: Super Contributor
timestamp: August 18, 2015, 04:30:49 am
content: I never thought of this but its a VERY good point and I would think that the reviews would cover this as well! I saw that post on the 87V. I wonder if that was a one off or if they normally run up that high."For those doing PCB reverse engineering and concerned about continuity testing damaging delicate componentry, I thought it good to link to this post and thread"I have attached the data I took for the hand held meters I have left. The HP I used to make the measurements is within cal.Even with as crappy as it sounds, a friend of mine had asked if I had put a speaker behind the UNI-T to make that video. I started out thinking I would just do a simple single note playback but dismissed it as too simple. If the short is there too long, the meter will beep. So getting it to sound this good took some work.

author: tautech
author_rank: Super Contributor
timestamp: August 18, 2015, 04:39:02 am
content: As usual closer examination of TE specs reveals the perfect equipment is hard to find.While the UNI-T continuity test might be blindingly fast, its voltage and current used for continuity is worse than the others in your table.

author: joeqsmith
author_rank: Super Contributor
timestamp: August 18, 2015, 04:58:03 am
content: I would normally throw out the fact that these are some pretty low cost meters and how you get what you pay for and Fluke is king. But then there is that 87V post. I need to check into that.

author: tautech
author_rank: Super Contributor
timestamp: December 17, 2015, 10:25:52 pm
content: Quote from: joeqsmith on August 16, 2015, 06:01:02 pmYou've got competition:https://www.eevblog.com/forum/chat/silent-night-being-sung-by-an-agilent-33120a/