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Digital two-wire irrigation control system

  • US 4,007,458 A
  • Filed: 12/29/1975
  • Issued: 02/08/1977
  • Est. Priority Date: 12/29/1975
  • Status: Expired due to Term
First Claim
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1. Decoding apparatus for use in an irrigation control system in which both power and control signals are transmitted from a central location along a single pair of conductors, said apparatus comprising:

  • rectifier means for generating a direct-current signal from a basically sinusoidal received power signal, and for dividing the power signal into a first signal reflecting power signal excursions only in one direction with respect to a zero reference, and a second signal reflecting power signal excursions only in the other direction, the presence of excursions of said first signal being indicative of encoded ones;

    electronic switch means for connecting the direct-current signal from said rectifier means to at least one valve solenoid;

    means for indentifying said decoding apparatus; and

    digital logic means utilizing complementary metal-oxide-semiconductor logic for deriving sets of control signals and decoder addresses from said first signal, and for operating said electronic switch means in accordance with those of said control signals accompanied by a decoder address equivalent to said means for identifying said decoding apparatus.

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