Computer Based Multimeter  - Page 1
Forum section: electronics / general

author: xicor
author_rank: Newbie
timestamp: February 15, 2014, 03:45:46 pm
content: Hi EveryoneI am looking for a computer based multimeter to measure DC amps&voltage. I will be using this to test RC motors and different propellers and measure thrust, what I am looking for is something like the product in the link below but something that can connect to a computer and record results.http://www.hobbyking.com/hobbyking/store/__10080__Turnigy_130A_Watt_Meter_and_Power_Analyzer.htmlthe closest I have found is (Medusa Research Power Plus) it has a usb interface but sadly this company no longer makes that product, I would greatly appreciate your advice on any products that you used or use that can be connected to the computer and record amps&voltage preferably something that costs less than £200.Xicor

author: Dago
author_rank: Frequent Contributor
timestamp: February 15, 2014, 04:10:53 pm
content: I would just use a couple benchtop DMM connected to a computer. Older ones have GPIB and newer ones have RS232 and even ethernet or USB. I admit your gonna have a hard time getting two of them for 200£ but they would be useful for tons of other stuff around the lab as well. I'm sure other people will have good suggestions on which models you could get for a fair price from ebay.Specifically I would suggest two benchtop DMMs (one for voltage and one for current) and if you really need to measure up to like 130A (like the device you linked) then maybe a current shunt as well. Depending on the DMMs you might need a USB->GPIB adapter.If you can't afford benchtop DMMs (or have no other use for them) I'd say you could always build one of those power meters that would connect to a computer. Would be fairly trivial with a microcontroller and an ADC and say a hall current sensor like this:http://www.allegromicro.com/en/Products/Current-Sensor-ICs/Fifty-To-Two-Hundred-Amp-Integrated-Conductor-Sensor-ICs/ACS758.aspxIt also might be possible to modify (or write your own software) for the turnigy one so you could connect it to a computer. The microcontroller it has most likely has an UART.

author: xicor
author_rank: Newbie
timestamp: February 15, 2014, 05:10:47 pm
content: Hi Dagothanks for your reply !DMM are indeed costly and beyond my budget, would be good to buy if i had other uses for them though. I think I will go with your suggestion and look into modifying the turnigy possibly connecting it to an arduino since I will also be using it to control the RC motors.Xicor

author: Marco
author_rank: Super Contributor
timestamp: February 15, 2014, 06:53:56 pm
content: Two cheapy USB DMMs which you can connect to the computer can easily be had, but only 6000 count if new and of questionable quality. Unless you can find some good second hand models I'd just hack something.

author: daqq
author_rank: Super Contributor
timestamp: February 15, 2014, 07:11:25 pm
content: You don't necessarily need a multimeter - better power supplies (such as the HP 6632B and similar) have precision measurement features as well as great reaction times.They have GPIB and RS232 (and newer models probably have USB and such).New - they are rather expensive, but you can get them (or similar ones) from ebay relatively cheap. I bought mine for 150 EUR and never looked back.

author: mariush
author_rank: Super Contributor
timestamp: February 15, 2014, 07:15:54 pm
content: An Uni-T UT61E costs less than 60$ and comes with pc connection cable (serial connector or usb)... the one with serial cable you can simply use a serial to usb cable to connect it to pc.The meter is supported by UltraDMM which can log several multimeters at the same time.The only problem I can think of is that the UT61E updates just two times a second, which may be a bit slow for you. It drops update speed in favor of lots of counts (22000) and precision.There are other meters supported by UltraDMM , including UT60A, UT60D, UT61 A/B/C/D/E etcSee what's cheaper on eBay, see reviews, see whats more convenient and which one gives you the best deal.Ah almost forgot, there's also this Digitek meter sold by a guy that's a user on this forum and has a very good reputation:http://www.ebay.com/itm/Digitek-DT-4000ZC-TekPower-TP4000ZC-Data-Logging-Multimeter-with-Temperature-/200912705694?pt=LH_DefaultDomain_0&var=&hash=item2ec754989eIt also has logging, it's not supported by UltraDMM but has the software to log stuff with it. It's cheaper (<40$ with shipping). The only "problem" with this meter is that it uses the same jack for current and voltage, so you have to be careful and select what mode you want the meter to be in BEFORE you plug (or connect) the cables.

author: mtdoc
author_rank: Super Contributor
timestamp: February 15, 2014, 08:13:14 pm
content: Quote from: mariush on February 15, 2014, 07:15:54 pmI have one of these and it is a great meter for the price.QuoteYou can also use it with the excellentQtDMM program- but it is Linux or Mac OSX only.QuoteNot quite correct. Amp and Voltage/Resistance are different jacks. But there is no separate jack for milli and micro Amp ranges.

author: xicor
author_rank: Newbie
timestamp: February 16, 2014, 01:31:28 am
content: thanks for all your replies guys, I think to start with I will use the turnigy or similar power analyzers and record the results manually on an excel sheet. at some point I will most likely work on something arduino-ish and make my own analyzer, its sad that Medusa Research are no longer aroundotherwise their solution is great.

author: senso
author_rank: Frequent Contributor
timestamp: February 16, 2014, 02:58:19 am
content: With some luck, maybe that power meter has an internal serial port just like the turnigy chargers, if so, just connect it to a ftdi cable.

author: xicor
author_rank: Newbie
timestamp: February 16, 2014, 01:00:15 pm
content: Bingo !! I think I found what I was looking for, It was in front of me the whole timecheck out the link belowhttp://www.hobbyking.com/hobbyking/store/__15941__Hobbyking_PowerLog_6S_Multifunction_Monitor_datalogger.html

author: Galenbo
author_rank: Super Contributor
timestamp: February 17, 2014, 07:24:08 pm
content: Quote from: xicor on February 15, 2014, 03:45:46 pmYou sound like a DIY hobbyist.Why not make the signal conditioning yourself (voltage scale, amp to volt) read the values in a PIC and send them by USB-UART to your PC? Here you make your own program in Processing, Labview or anything else.