Measuring 16 signals with one multimeter - Page 1
Forum section: electronics / general

author: Cloud
author_rank: Regular Contributor
timestamp: March 27, 2018, 11:47:07 am
content: I have 8.5 digit multimeter, with which I would like to measure 16 different voltages (they have to be measured differentially). What do you recommend? Does some reasonably prices solution exists or does it have to be build from scratch

author: TiN
author_rank: Super Contributor
timestamp: March 27, 2018, 12:20:31 pm
content: Since TS didn't specify signal requirements, budget or any other specs, hard to recommend anything. Scanner box such as Keithley 7001 with card likely be suitable for your 16 different voltage requirements. I had good results with Keithley 7168 JFET-scanner card (8 channels only though, so you'd need two of these) to read DC references array.

author: Echo88
author_rank: Frequent Contributor
timestamp: March 27, 2018, 12:27:36 pm
content: Since Keithley 7168 is basically unobtanium, i would suggest a Keithley 7001 or 705 Scanner Mainframe + 20-channel-relay-card Keithley 7064 (or two Keithley 7059 cards with each 10 relay-Channels). The Keithley relays only introduce <1µV voltage-error into the differential voltage measurement due to the low-emf-design.https://doc.xdevs.com/doc/Keithley/70xx/7064_901_01C.pdf

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 27, 2018, 04:47:45 pm
content: https://www.eevblog.com/forum/projects/diy-low-thermal-emf-switchscanner-for-comparisons-of-voltage-and-resistor-stand/msg1366769/#msg1366769Measurement that I made on my design show below10nV (measurements are 2nV...8nV depending on channel #) of thermal EMF.It would be nice to confirm this result with other owner of the nanovoltmeter.This uses modified Ethernet cables.I've just finished 5 units but have no time to describe further.P.S. To obtain these results the scanner is mounted inside aluminium enclosure.

author: cellularmitosis
author_rank: Unknown
timestamp: March 27, 2018, 05:59:52 pm
content: doktor, I am very glad to see an update on your scanner -- a great little design. Glad to see it performs so well.

author: Cloud
author_rank: Regular Contributor
timestamp: March 28, 2018, 10:44:41 am
content: Thank you for all the answers.I have to check but I think that scanner box would be to expensive to get with calibration certificate.@doktor pyta thanks for that I think that this would probably be the right solution

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 28, 2018, 03:47:28 pm
content: Answering some questions:1. This is relatively simple project, but the aim was to make it versatile -this took 7 revisions +lots of components bought just to try if their dimensions and performance is good enough.I'm not complaining, just wanted you to know.2. No, I'm not planning to send You Altium project.3. When ordering new revision of PCB's (RFS135B) I may order some more for the users.4. If more than 10 people is interested I may try to make several DIY kits, but please give me some time.

author: cellularmitosis
author_rank: Unknown
timestamp: March 28, 2018, 04:08:53 pm
content: Quote from: Cloud on March 28, 2018, 10:44:41 amThere are also scanner "mainframes" which don't include a DMM (is that what you meant by calibration?)

author: Cloud
author_rank: Regular Contributor
timestamp: April 09, 2018, 08:27:46 am
content: Just to give quick update:This signals can be measured with "Indication only" multimeter.One idea was to use NI DAQ (but I hate NI and DAQ has only USB connection).So now we are testing Keysight 34972A.