CR4® - The Engineer's Place for News and Discussion®


Previous in Forum: DNA Origami Forms Copy of Van Gogh Painting   Next in Forum: Breeding Birds for Intelligence
Close
Close
Close
15 comments
Anonymous Poster #1

Data Acquisition Device

07/26/2016 1:33 PM

I'm doing a project which involves measuring current/voltage difference in a solution due to microbial degradation activity. I need some suggestions on the data acquisition device that I should use that is compatible with MatLab.

Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru

Join Date: Oct 2008
Posts: 39881
Good Answers: 1587
#1

Re: Data Acquisition device

07/26/2016 2:06 PM

Your question is FAR too broad for a person using MatLab.

You should know this, or know how to find it.

First, use a search engine.

Type this "data acquisition device compatible with MatLab".

Data Acquisition Software - Data Acquisition Toolbox - MATLAB

Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 19235
Good Answers: 1125
#2

Re: Data Acquisition device

07/26/2016 3:01 PM
__________________
Life is like riding a bicycle. To keep your balance you must keep moving. A.E.
Reply
2
Guru
Engineering Fields - Electrical Engineering - Been there, done that, still doing it. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 12217
Good Answers: 774
#3

Re: Data Acquisition device

07/26/2016 3:57 PM

Matlab® can be the analysis program but you are clearly putting "the cart before the horse" worrying about how to analyze signals before you have signals.

The first things one needs to identify are the anticipated voltages, currents (electric or fluid) and frequencies of these signals. Then comes the number of these signals that one needs to measure simultaneously. Don't forget that one will have to determine an appropriate method on how to probe this solution, too. Once a reasonable guess on these parameters have been made then one can consider which hardware can be used. Now you will have the wonderful conversation with the one who holds the money about costs. Usually this conversation causes at least one redesign.

Good Luck

__________________
"Don't disturb my circles." translation of Archimedes last words
Reply Good Answer (Score 2)
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 13438
Good Answers: 152
#4

Re: Data Acquisition device

07/26/2016 4:19 PM

Redfred has already told you: find signals first, and what magnitude they are. Then you can figure out what voltage range you need for data acquisition.

For example, if Vout = 0.237 V, then you would not use a 16 bit 0-10 volt scale data logger.

Have you considered making your own amplifier boards? Then input the signals to an Arduino, and convert them to digital, etc.

__________________
If it ain't broke, don't fix it. Just build a better one.
Reply
Guru

Join Date: Dec 2016
Posts: 2914
Good Answers: 115
#11
In reply to #4

Re: Data Acquisition device

12/11/2016 4:52 PM

Having ever used only one Arduino (an Uno) I cannot say if this is true of Arduinos generally, but the A/D converters on mine are the noisiest I have ever used, bar none.

On the flip side, they make for great (atmospheric/thermal-noise-based) random number generators.

Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 13438
Good Answers: 152
#12
In reply to #11

Re: Data Acquisition device

12/12/2016 1:45 PM

Pair wires, untwisted? Twisted pair? Shielded cable?? Signal level and frequency?

It is possible also to take more frequent data than is needed, and average the readings, and this can (but not always) cancel out some of the noise.

I agree that there are much better data loggers out there on the market, for not a lot of money, that can take negative signals as well as positive while Arduino can only deal with positive going signal, since negative will toast the board. One can try using diode (reverse bias to positive), to protect from negative signal so I have heard, have not tried that.

__________________
If it ain't broke, don't fix it. Just build a better one.
Reply
Guru

Join Date: Dec 2016
Posts: 2914
Good Answers: 115
#13
In reply to #12

Re: Data Acquisition device

12/12/2016 3:26 PM

Yeah, for bipolar signals you would need to do level-shifting externally (and very likely scaling and maybe some other signal conditioning) first, then remove the shift bias in software, a trivial operation. Signal averaging in software to reduce noise; median filters also work well. I use median filters to process the data from two CdS sensors on a simple one-axis optical tracker built using the Uno and a cheap servomotor:

It's not the sensors that are noisy, it's the A/D! It's so bad on mine that it might as well have 7- or 8-bit channels instead of 10. The first few LSBs are all over the map; marginal improvement when connected to relatively low-impedance signal source but never really goes away.

My app is basically just a toy, but for any truly serious work I would not consider using an Arduino. Plus - and as others have already mentioned - the OP didn't say anything about the nature of the signals he/she's trying to measure. AC? What frequency? Frequency range? Amplitude? Unipolar signals? Bipolar? (gasp) Quadrature? DC levels? And this is just for starters.

OP? What say ye?

Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 13438
Good Answers: 152
#14
In reply to #13

Re: Data Acquisition device

12/12/2016 4:49 PM

As per usual they leave the building just when things get interesting.

__________________
If it ain't broke, don't fix it. Just build a better one.
Reply
Guru

Join Date: Dec 2016
Posts: 2914
Good Answers: 115
#15
In reply to #14

Re: Data Acquisition device

12/12/2016 5:54 PM

Yes, you'd think in five months' time they could come up with more info. Hopefully they followed the advice given above and found their answer.

Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16274
Good Answers: 631
#5

Re: Data Acquisition device

07/27/2016 5:16 AM

Pencil and paper?

Del

__________________
health warning: These posts may contain traces of nut.
Reply Score 1 for Good Answer
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 13438
Good Answers: 152
#6
In reply to #5

Re: Data Acquisition device

07/27/2016 9:59 AM

Excellent concept, and with a recording frequency only limited by the user's dexterity.

__________________
If it ain't broke, don't fix it. Just build a better one.
Reply
Guru

Join Date: Oct 2008
Posts: 39881
Good Answers: 1587
#7
In reply to #5

Re: Data Acquisition device

07/27/2016 3:59 PM

Paper and pencil is too unreliable.

Stone tablet and chisel is recommended.

Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 13438
Good Answers: 152
#8
In reply to #7

Re: Data Acquisition device

07/27/2016 4:10 PM

Well, it does make a more permanent record. What in hell did Romans do when they goofed up? Did they just make paving material out of it?

__________________
If it ain't broke, don't fix it. Just build a better one.
Reply
Guru

Join Date: Oct 2008
Posts: 39881
Good Answers: 1587
#9
In reply to #8

Re: Data Acquisition device

07/27/2016 5:17 PM

They got a new scribe to replace the recently deceased scribe and used the obverse side of the tablet.

Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 13438
Good Answers: 152
#10
In reply to #9

Re: Data Acquisition device

07/28/2016 4:38 PM

I tried to hand you a GA for that one. ROFLMAO!

__________________
If it ain't broke, don't fix it. Just build a better one.
Reply
Reply to Forum Thread 15 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

Andrew Westman (3); Del the cat (1); James Stewart (6); lyn (3); redfred (1); SolarEagle (1)

Previous in Forum: DNA Origami Forms Copy of Van Gogh Painting   Next in Forum: Breeding Birds for Intelligence

Advertisement