gas sensing circuit help!!!!

Calcium carbonate (limestone). Check a tropical fish store for materials. Offer a chem student a six of their favorite brew, and they'll explain it to you in detail.

You might want to also google pH meters.

Possibly you can arrange to get an extension.

Chris

Is there different IR absorption versus CO2 level, at a particular IR wavelength passing through the seawater? (I seem to recall that's the principle behind the gas-type sensors.) Then the "raw material" could be the seawater itself. Or is there some qualification on what constitutes a "raw material"?

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

I think he means that he needs to build his unit from scratch using discrete parts, rather than purchasing ready made assemblies (such as a complete commercial CO2 meter).

ya, that's what i mean~ cos the problem is, i just need to find that one part!! that sensor or detector part!!! without that, i can't do anything....

Ahh, now I think I understand: You want the sensor, but not the whole packaged CO2 measurement instrument. Just Google for "CO2 sensor" and you'll find plenty of hits.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

Engineering Degree Jeopardy!

Category: Senior Projects for 3 semester credits and a required course, Alex.

ed_ker> hi~ i'm doing one of my fourth year course projects in EE, i need to

Alex: The answer is, "You need a ____ sensor to measure CO2 levels in salt water."

Questi> ya, that's what i mean~ cos the problem is, i just need to find that

(Sorry about not top-posting, Mr. Fields)

C'mon. What happens when CO2 dissolves in water? If you don't know, ask anyone who's taken a high school chemistry class. Possibly you might want a sip of Pepsi while you're thinking, it might help you come up with an answer. Obviously, to measure it you'll need a ____ meter, and to make one of those, you'll need a ____ electrode.

It's amazing that you've gotten to T-minus two weeks in your senior project class, and you still don't know what you're going to do. More amazing that with two weeks left, you still don't even know what you don't know. And most amazing, you're burning literally days on a newsgroup trying to get a clue when you've got only three hundred hours or so (less than two weeks) left.

There comes a time when it's cruel to let someone keep suffering -- you really should ask for an extension, arrange for some kind of unavoidable, unfortunate, unverifiable event to happen (no clues from me -- try alt.slacker.undergrad for advice) that will require the department head to give you an incomplete, or just submit to the inevitable and take your medicine as prescribed. There are worse things in life than having to take senior projects over again. Like getting a degree in engineering without being able to marshal information, develop project timelines and milestones, and discipline yourself to get things done, putting it in overdrive until you know you're ahead of the ball, and turning the afterburners back on whenever you get stuck. The real world of engineering will crush you. That is, unless you have a government job lined up or are planning on working in your daddy's firm.

It's kind of a shame -- the project could be a fairly simple and straightforward one, based on your ____ electrode, a couple of high input impedance, low drift op amps, a chopper for stabilization, and the analog front end tied to a good resolution A-D conversion and a neat digital end with a good uC to take care of the display and housekeeping functions. Nothing bleeding edge, but definitely worthy of an A, especially with a good manual and writeup. But less than 2 weeks just isn't enough time.

Well, you might just be able to get a proof-of-concept up and running in that time if you don't sleep, anyway. And there's always hope for an extension. So, against my better judgment, fill in the blanks by looking at this:

and then enhance your knowledge by buying a six for a chem major today and having them enlighten you.

By the way, your message string has umich.edu in there. Tell me you're not from the University of Michigan. Please.

Good luck Chris

p.s. -- When you get the thing you're looking for, buy two or three good ones -- they die at the most inconvenient times. No cheapies or freebies here. And buy or borrow the additional things you need and follow the instructions for ____ electrode care and feeding. They want to be bad, but like any good cat, they'll treat you barely adequately if you pamper them. But also like most cats, they spend a lot of their time wondering if there's a way to make your life miserable when you ignore them, especially if you need both accuracy and precision. And you will. You will. So watch out.

p.p.s -- I hope I've done you proud, Mr. Fields.

Hi, Mr. Fields. Usually not, but these are troubled times, no?

Should have read "Sorry about mixing up the posting order".

Guys like this who need someone to do their senior project for them tend to get me irritated, and the umich.edu sent me over the edge. That's too much -- Michigan has a first rate engineering school, and several of the best engineers I've had the privilege of working with and for have matriculated from there.

Either that, or it's just another troll.

There are times when you have to turn up the heat a little, if for no other reasons than to improve the breed and to impress upon them that their education means something. They have no business wasting it grooving to their iPods in seminar, then coming to a newsgroup of all places and whining with multiple exclamation points and caps when there's two weeks left that no one is helping them.

They're needy ones, alright. Once upon a time, the needy ones were weeded out by second semester, and shunted into beery, fun-filled journamalism majors or back to Junior College. Especially at Ann Arbor.

It's always a pleasure reading your posts. I just thought you might have found it amusing that someone else had gotten ticked off here, especially after the last few days.

Cheers Chris

And what do you think the odds are the troll/needy one posts back and says he still doesn't get it? ;-)

Cheers Chris

Chris, he doesn't need "first principles" here, he just needs to buy a ready-made sensor from TI or somebody. The whole problem was apparently a language issue: He was saying "raw materials" but he really meant "sensor". Simple task with Google... why, in MY day we had to thumb through huge "IC Master" volumes and call reps and plead for special consideration to get a sample, or lie and say it was for a prototype before we hit volume production. Kids have it SOOO easy these days! ;-)

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

Phone? You had a phone? I had to write letters and wait, and wait...