Alt-BEAM Archive
Message #01537
To: beam@corp.sgi.com, "'Steven Bolt'" sbolt@xs4all.nl
From: "van Zoelen, Bram SSI-TSEA-352" Bram.A.A.vanZoelen@is.shell.com
Date: Tue, 16 Mar 1999 12:51:59 +0100
Subject: [alt-beam] Re: `Green Thumb'
Nice gadget.
But some thoughts for further developement.
Put the surplus of energy you got from the solarcel into a capacitor like a
solar engine.
With this stored energy you can control a 'normal-closed' valve thats in a
dripping system.
This way you only have to fill a large resorvoir with water and the plant
will get water on demand.
Bram
> ----------
> From: Steven Bolt[SMTP:sbolt@xs4all.nl]
> Reply To: Steven Bolt
> Sent: Tuesday, March 16, 1999 11:37 AM
> To: beam@corp.sgi.com
> Subject: `Green Thumb'
>
>
> 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 #
> ----------------------------------------------------------------------
>
>
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