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digital pressure measurement.

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digital pressure measurement.

Unread postAuthor: SpeedyFerrite » Wed Jun 13, 2007 4:11 am

I was wondering, what if you hook up a digital pressure gauge up to a Micro controller to read the output, that would work, right?

(I honestly don't know any other way to make this question sound any dumber)

I also was doubting Between putting it in combustion cannon discussion or in hybrid cannon discussion. So I put it in the totally unrelated forum.

Anyway, thanks in advance *hic*
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Unread postAuthor: jimmy101 » Wed Jun 13, 2007 12:00 pm

Yes this would work. Depending on the pressure gauge you might be able to plug it directly into a PC, that would be a lot simpler than using a micro controller.

The problem is getting a digital (or analog) pressure transducer that is fast enough (response time less than ~1mS), has a suitable pressure range (up to a couple hundred psi) and doesn't cost a zillion dollars. I've looked for suitable gauges and all I've ever found run from about $70 to several hundred dollars each.

Here is my ghetto setup for measuring the "pressure" versus time in a combustion gun using a piezo transducer.
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Unread postAuthor: boilingleadbath » Wed Jun 13, 2007 7:31 pm

How fast are the devices in consumer-level digital pressure gauges?
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Unread postAuthor: Bubba05 » Wed Jun 13, 2007 10:47 pm

Im pritty sure they'd be pritty quick? maby you could sorse a industral device that could be fast enough to read the pressusre in real time?

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Unread postAuthor: SpeedyFerrite » Thu Jun 14, 2007 2:35 am

Thanks for the replies!

Jimmy: I might try that piezo thing you posted a link about. :)

The gauge doesn't need to be that fast, it's for metering fuel in a hybrid. :)

*Edit* the link to the radio shack site does not work, do you mean a piezo buzzer maybe?

*edit 2* http://nl.farnell.com/jsp/Industrial+Controls+&+Automation/Ultrasonic/MURATA/MA40B8R/displayProduct.jsp?sku=1006202

Or something like that maybe?
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Unread postAuthor: jimmy101 » Thu Jun 14, 2007 2:21 pm

I purchased a $2 "Bilingual talking tire pressure gauge" from RadioShack. I should have gotten two so I could rip the pressure transducer out of one of them.

Not real accurate, compared to a couple of standard pressure gauges it reads about 6 PSI high (at 30 PSI).

No idea if the pressure transducer itself will respond fast enough to monitor the combustion chamber. It should respond fast enough for a meter.

Next time you are near a RS check to see if they have'm. (Last I looked on their web site they were sold out but individual stores might still have them.)

For $2 you can't go wrong.

The voice sounds like Boomhauer (sp?) from King of the Hill.
(Click here to hear what the gauge sounds like.)

here is what the gauge looks like;
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SpeedyFerrite: The thing you linked to is an ultrasonic receiver. I don't think that will work. You just want a crappy old piezo element (like the one in talking birthday cards). The case is not required, nice if it has wires already soldered on.

The one I used was similar to [url=http://www.allelectronics.com/cgi-bin/item/PE-35/466/1.36%22#34;_DIAMETER_X_0.34%22#34;_ENCASED_PIEZO_.html]this[/url] one.
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The big problem with the piezo element is that it doesn't measure pressure, it measures dP/dt (change in pressure over time). So, it works OK for measuring the pressure pulse in a cannon but I don't think it will work for the slow pressure change you would get in a meter.
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