Uni-trend UT-M03 & UT-M04 (accessories for UTD-4102C) - Page 1
Forum section: electronics / testgear

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 16, 2019, 12:55:41 am
content: When I bought my scope (Uni-T UTD-4102) it came with a few accessories which included two small boxes.UT-M03 & UT-M04Both of these are shown in the instruction manual in the list of contents but, other than that, there is no mention of them.They appear to be current to voltage convertors. If that's the case do they simply allow you to read current as a voltage? The device is built to plug into the positive and negative "DMM" input so is it just to give a current input to the built-in DMM? I can't imagine anybody would use for that as it is far less useful than an actual DMM and anyone buying a scope of this price would have a better DMM anyway.

author: Fiveohfour
author_rank: Contributor
timestamp: February 16, 2019, 01:30:52 am
content: I would’ve guessed they’re for current clamp accessories that you can buy for scopes/bench meters, but can’t actually saySent from my iPhone using Tapatalk

author: threephase
author_rank: Regular Contributor
timestamp: February 16, 2019, 09:13:21 am
content: They look like current shunts to me. Input wired in series in the circuit under test and then the output to the oscilloscope as a voltage. Similar to the Omicron ones I have and the Keysight 34330A.

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 16, 2019, 09:34:14 am
content: Quote from: threephase on February 16, 2019, 09:13:21 amThanks. It's what I guessed but what is the point? If you have a decent scope I'm sure you would have a multimeter so why bother with these add-ons in order to use the scope as a DMM? Seems pretty pointless to me.

author: danco
author_rank: Newbie
timestamp: February 16, 2019, 03:53:10 pm
content: I believe it is the same as for the voltage, you certainly have a DMM to measure the voltage, but the scope tells you much more about it, the same you can see about the current in a circuit, the DMM can't show you fast variations so here lays the use for these "magic" boxes. Just my thought.Sent from my MI 5s Plus using Tapatalk

author: joeqsmith
author_rank: Super Contributor
timestamp: February 16, 2019, 05:29:05 pm
content: Did they supply some sort of banana to BNC adapters as well to use them with the scope? The couple of ads I found did not show these being included.

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 16, 2019, 09:48:45 pm
content: I've just used the UT-M04 to measure the power usage of a cheap 5/7.5/10v ref I got off ebayReadings using the UT-M04* against Keithley 2100 & Philips PM2525 (I've just taken these readings for another thread!)eading >>>>> Cheap 5v ref 10w 100ohm res Volt ref draw PP3Keighley 2100 5.01068v 98.9082 0.85924 mA 9.49572vUNI-T UTD4102C 5.00v 98.6 0.859 mA * 9.49Philips PM2525 4.98v 99.01 0.8580 mA 9.47UNI-T UT60E 5.01v 98.8 too low 9.49So maybe it is a useful device after all, it's as accurate as a dedicated DMM costing twice as much (although only to 3places rather than 5)

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 16, 2019, 10:43:18 pm
content: The boxes both have a pair of banana plugs/sockets. It only plugs into the DMM socket and gives you two female sockets to plug the supplied DMM leads into. They are basically just for using to measure current via the DMM input. I used them this evening and they are as accurate as my best DMM through the range they measure but my original point is still true as far as I see it ie. Why would you. I suppose there may be niche reasons such as using the logging capabilities of the scope's DMM input and as they were free (well included) I'm not actually complaining but maybe at least explaining them might have been useful. I am loathed to experiment beyond what I know with my expensive test equipment that is no longer in warranty and would rather at least see that what looks right is....

author: threephase
author_rank: Regular Contributor
timestamp: February 17, 2019, 08:57:03 am
content: I guess you could ask why you would add DMM functionality to a bench based scope in the first place? Most people who have gone to the expense of a scope are also likely to have DMMs, unless they are thinking that their scope can provide a one stop approach for a small / hobby workshop?If they are thinking that, then I guess wanting to measure current with a DMM is not unusual and having the current functionality added via external shunts is probably easier than building it into the scope hardware. My Omicron transient analyser works on the same principle, the unit can only measure voltage, so I have current shunts and set up the channel accordingly to turn the mV to an amps reading.I think I once used the DMM function of a USB scope when I was working out in the field and my DMM failed, but it is rare for me to use that side of a scope - on the other hand, there may be people who use such functionality regularly because of the type of work they do.When I review an insulation tester, I do sometimes measure the short circuit output current via a current shunt and an oscilloscope to get a trend plot, the only other time I have come across such current shunts is to extend the current range of a DMM up to 30A or so.They are probably missing a trick though if they haven't included BNC to banana adapters to allow them to be used on a scope channel, you can then monitor current and voltage as a time synced pair of signals.Kind regards

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 17, 2019, 10:18:56 am
content: Quote from: threephase on February 17, 2019, 08:57:03 amSo a BNC cable to twin banana plug cable and the scope set to x1 should allow a current trace?

author: threephase
author_rank: Regular Contributor
timestamp: February 17, 2019, 04:29:31 pm
content: Yes, a BNC to 4mm sockets would allow you to plug the UT-MT03 / 4 into the oscilloscope channel and record it as a mV trace. If the scope has a custom probe facility, you may be able to set the channel up to convert that mV into Amps via the relevant ratio. I am not familiar with the UTD-4102C, so do not know if you can do this.Example adapter shown below, the UT-MT03 /4 needs to be connected up as it would be for the DMM connection, as the internal leads for the mV signal may not be capable of taking the current.

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 17, 2019, 05:34:25 pm
content: I realised that I have a couple of banana to BNC adapters so will be able to hook it up now.Thanks.

author: Fiveohfour
author_rank: Contributor
timestamp: June 30, 2019, 01:40:49 am
content: Quote from: threephase on February 17, 2019, 08:57:03 amI am so ignorant when it comes to this field. Do you have any suggestions for crash courses on electrical theory? I want to do things far beyond my level of understanding. Inrush current alone, a single definition/term, has first fascinated me and then infuriated me because I cannot get straight answers even engaging engineers from Fluke, Klein, and AEMCI NEED THE MATRIX TRAINING CODE.Actually the screens showed it’s all just 1’s and 0’s, can’t be that hard after all, now to just find a reputable tattoo parlor to fabricate and surgically embed wildly futuristic (& equally wildly giant and industrial in appearance) high speed brain interconnect/bus to put in my skullSent from my iPhone using Tapatalk