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Soil moisture indicator device

  • US 4,020,417 A
  • Filed: 11/26/1975
  • Issued: 04/26/1977
  • Est. Priority Date: 11/26/1975
  • Status: Expired due to Term
First Claim
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1. An indicating device for testing the moisture content of soil about the roots of a plant comprising:

  • a power supply,a first indicator circuit connected across said power supply and including a first semiconductor switching means in series with a first indicator light,a second indicator circuit connected across said power supply and including a second semiconductor switching means in series with a second indicator light,control circuit means connected across said power supply with its current path completed through the soil to be tested, said control circuit means comprising an unbalanced resistive bridge having junctions on the opposite sides thereof respectively providing output voltages for controlling said first and second semiconductor switching means,whereby said control circuit means adjusts the output voltages on said junctions in response to the resistivity of the soil to cause one of the semiconductor switching means to conduct to illuminate its associated indicator light if the moisture content of the soil is at least adequate and to cause the other said semiconductor switching means to conduct to illuminate its associated indicator light if the moisture content of the soil is excessive.

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