From: Joseph Legris
X-Mailer: Mozilla 4.77 [en]C-SYMPA (Win95; U)
Subject: Re: Rain intensity to voltage idea... Opinions?
Date: Fri, 04 Oct 2002 18:31:10 -0400
NNTP-Posting-Date: Fri, 04 Oct 2002 18:25:19 EDT
Organization: Bell Sympatico
Jim Thompson wrote:
> On Fri, 04 Oct 2002 16:21:21 -0500,
> NightRunner ,
> In Newsgroup: sci.electronics.design,
> Article: ,
> Entitled: "Re: Rain intensity to voltage idea... Opinions?",
> Wrote the following:
> |On Fri, 04 Oct 2002 19:23:22 GMT, Jim Thompson
> |, masquerading as a MSNBC reporter, said
> |the following to White House press secretary Ari Fleisher during a
> |press conference concerning the New War:
> |>(1) Capacitor microphone, amplify noise, rectify and filter output.
> |Yeah, great for days where the birds are making more racket than the
> |cicadas and katydids, which is quite impressive to behold out here...
> |Potentially workable, but I just don't like the idea of non-rain
> |events causing a jump.
> I had in mind constructing your own capacitor microphone with such
> gross dimensions that only a surface impact would create a signal.
> |>(2) Bucket with small hole in bottom, then measure height of water in
> |Then I need electrodes in the water to allow me to graph depth. Every
> |so often I need to clean the electrodes or recalibrate... Remember, we
> |are talking rainwater here, not microfiltered, deionized bottled
> Use a tapered vessel so you get a logarithmic output.
> |Here's an interesting method along the lines of using probes. Use
> |carbon pencil leads (like drafting compass refills) instead of metal
> |for a resistance that decreases as the water level rises. Bad points:
> |The carbon probes will still eventually need cleaning or replacement,
> |and carbon is quite brittle. Also would probably regularly need to
> |clean the surfaces where the wires contact the probes. My brother gave
> |me the idea for this when we were kids. He went though a phase where
> |he was in love with hydrolysis, and made little pencil carbon arrays
> |to greatly increase the surface area of gas production without
> |corrosion on the electrodes. It occured to me that a typical variable
> |resistor is just a wiper contact along a carbon track, and a long
> |pencil lead would make a great depth probe.
> You probably can make capacitance work, *except* you will need to
> slope it to allow for run off, and calibrating may be difficult.
> | - NR
> ...Jim Thompson
> | James E.Thompson, P.E. | mens |
> | Analog Innovations, Inc. | et |
> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
> | Phoenix, Arizona Voice:(480)460-2350 | |
> | Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
> | http://www.analog-innovations.com | 1962 |
> For proper E-mail replies SWAP "-" and "_"
> I love to cook with wine. Sometimes I even put it in the food.
I like the microphone idea, but as a sound board you MUST use corrigated
steel :-) Drains nicely too.