Alt-BEAM Archive

Message #01560



To: Steven Bolt sbolt@xs4all.nl, BEAM List beam@corp.sgi.com
From: Chiu-Yuan Fang chiumanfu@home.com
Date: Tue, 16 Mar 1999 17:25:25 -0800
Subject: [alt-beam] Re: `Green Thumb'


Very nice! Too bad I just bought a $50.00 moisture meter for my garden.
http://start.at/hydroponics

I still need a pH meter and an EC meter...any ideas Steven.

Chiu

Steven Bolt wrote:
>
> Most potted plants get either too much or too little water. Their
> performance is greatly improved if you give them just enough.
> The `Green Thumb' is a solar powered sensor which makes that very
> easy.
>
> Linkname: Green Thumb
> URL: http://www.xs4all.nl/~sbolt/e-groeneVinger.html
>
> Soil resistance is measured using a tiny alternating current (less
> than a microwatt) which avoids galvanic trouble at the sensor poles
> and isn't noticed by the plant. The circuit compares pulse delays
> which depend on the soil and on an adjustable resistor. The ratio
> between these delays does not depend on the supply voltage. So
> despite the wide fluctuations of a solar power supply, the sensor
> output is accurate and reliable.
>
> Prototypes of the Green Thumb have been doing a good job for
> various plants since last spring. Two months ago, I started one on
> a few lemon geranium (Artemisia abrotanum) cuttings. That plant is
> now more than 60cm high, and its thirst as indicated by the Thumb
> is ten times greater than it used to be. When the summer sun hits
> my window, its water needs are expected to triple.
> That kind of variation is difficult to keep up with, unless you
> have green thumbs - or a Green Thumb :)
>
> Enjoy,
>
> Steve
>
> ----------------------------------------------------------------------
> # sbolt@xs4all.nl # Steven Bolt # popular science monthly KIJK #
> ----------------------------------------------------------------------

--
Chiu-Yuan Fang
chiumanfu@home.com
ICQ=5614919
http://www.geocities.com/SouthBeach/6897/beam2.html

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