Idea: Multimeter that could log to an SD card? - Page 1
Forum section: electronics / testgear

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 05:51:51 pm
content: Something I just thought of, instead of using internal memory or an IR port, a multimeter could have a slot for an SD or micro SD (standard SD would probably be preferred) to log data to, that way you could log a pretty massive amount of data, and could swap SD cards if you needed to continue logging but get the data for the previous few days without interruption, or something along those lines.Just another random idea I had.

author: mariush
author_rank: Super Contributor
timestamp: May 14, 2014, 05:55:54 pm
content: Lots of multimeters have the data logging protocol documented and available... see the multimeters in UltraDMM, including the UT61E.It's a piece of cake to make a small "adapter" with a PIC/Arduino and a SD card slot to log records to SD card.

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 06:00:17 pm
content: Quote from: mariush on May 14, 2014, 05:55:54 pmFair enough, though you would need to power it, whereas if it were built it you would not. A combination of IR or micro SD would probably be the most handy, if the market called for it, but I doubt it will be made.

author: mariush
author_rank: Super Contributor
timestamp: May 14, 2014, 06:07:52 pm
content: The market is too small. Lots of multimeters go straight to Bluetooth/WiFi modules so that you can log data into a cellphone or tablet, and that works betters because you have the data directly available to have graphs in realtime and so on.I was thinking of making a pass-through adapter for the UT61E I have, to log data into a FRAM memory chip and send to PC at same time, but I'm just too busy (and lazy) to start such a project.

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 06:27:53 pm
content: Quote from: mariush on May 14, 2014, 06:07:52 pmTotally slipped my mind that they are doing Bluetooth now, that is far better than an SD card.

author: HKJ
author_rank: Super Contributor
timestamp: May 14, 2014, 07:27:03 pm
content: Quote from: XOIIO on May 14, 2014, 05:51:51 pmThere is a problem with the isolation, in a CAT3 meter it must handle fairly high voltages, making it difficult to access the card.One meter that will support it is the Mooshimeter:http://www.dragoninnovation.com/projects/34-mooshimeterBluetooth is not always better than memory. If you need to log something for a couple of days, it can be problematic to leave you phone to record it.

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 07:28:21 pm
content: Quote from: HKJ on May 14, 2014, 07:27:03 pmWell, I figure the Bluetooth would just be to dump the internal memory to your phone.

author: jpb
author_rank: Super Contributor
timestamp: May 14, 2014, 07:39:48 pm
content: Quote from: HKJ on May 14, 2014, 07:27:03 pmI guess if you are monitoring for a couple of days you could use a pc or a laptop but I agree just saving to an internal card would save power and be much easier.A lot of DMMs have internal memory but generally it is not very big. It would be better just to increase the size of this rather than compromise the robustness of the housing by having an external slot for an SD card.

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 07:56:13 pm
content: Quote from: jpb on May 14, 2014, 07:39:48 pmAgreed, but a multimeter that could parasitically charge while measuring current or voltage, say from a solar array, while datalogging to a 64gb sd card would allow some massively long term datalogging.

author: HKJ
author_rank: Super Contributor
timestamp: May 14, 2014, 07:59:46 pm
content: Quote from: XOIIO on May 14, 2014, 07:56:13 pmJust make the electronic low power, the mooshimeter I linked above promises 6 month logging on one set of batteries.

author: jpb
author_rank: Super Contributor
timestamp: May 14, 2014, 08:02:41 pm
content: Quote from: XOIIO on May 14, 2014, 07:56:13 pmThat is an interesting idea, but would go a bit against the normal design target of DMMs to not load the circuit under test in any way (or at least as minimally as possible).

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 08:53:22 pm
content: Quote from: jpb on May 14, 2014, 08:02:41 pmYeah.I think there is a UNI-T multimeter that has a solar panel but can also charge through the jacks, though that is on a charging mode, not at all times.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: May 14, 2014, 09:21:58 pm
content: This was actually my "get into electronics" project! Naturally, the results were... basic. But it worked, and it helped me solve the problem at hand: monitor car battery voltage over weeks and temperature changes.But I guess it's not often one wants to do long-term, on-site monitoring like that? Or is it that the data collected is too custom to each task?(I did it with aTeensy, which has a very easySD adaptor.)

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 09:53:09 pm
content: Quote from: Galaxyrise on May 14, 2014, 09:21:58 pmDid you make a multimeter adapter or was the teensy itself used to monitor voltage?

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 14, 2014, 09:57:28 pm
content: OpenLogis an open source data logger that stores data on micro-SD card...https://www.sparkfun.com/products/9530US$25SparkFun also has other similar small logging gadgets.

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 10:03:28 pm
content: Quote from: Richard Crowley on May 14, 2014, 09:57:28 pmNeat, though sparkfun stuff has always been pretty expensive when things like an ebay arduino pro mini you can get for a few bucks, or even one if you get lucky work just as well, I've got four or five that haven't been touched and it cost a fraction of the standard price. I'd probably just use one of those with a micro SD adapter. (though the micro SD adapters are more expensive than standard SD adapters by a decent margin.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: May 14, 2014, 10:17:01 pm
content: Quote from: XOIIO on May 14, 2014, 09:53:09 pmI used the 10-bit ADCs on the teensy itself to monitor the car battery (via resistive divider), the Teensy's battery (another divider), and a thermistor. Certainly not precision measurements, hehe. I put the teensy in a box with a plug to go into an always-on cigarette lighter. (And a connection for a 4xAA battery pack.) Depending on the program I had on there, battery life was from 1 to 3 weeks running on rechargeables. The biggest "problem" was the lack of a RTC; I had to correlate time 0 to UTC by hand.The teensy was very easy to work with, but not nearly as cheap as a few bucks!

author: XOIIO
author_rank: Super Contributor
timestamp: May 14, 2014, 10:19:54 pm
content: Quote from: Galaxyrise on May 14, 2014, 10:17:01 pmYeah, but not a bad solution.Honestly if it's something I would re-use a lot, I could see possibly justifying the high price but in a project where I am just going to leave it, it seems like quite a waste.