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[Need Help]Read circuit,,

Discussion in 'General Electronics Chat' started by cacingidop, Mar 2, 2011.

  1. cacingidop

    cacingidop New Member

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    Hi,

    Can someone please read this circuit about 'automatic watering plant' for me,,

    any help appreciated,,

    This circuit have been modified by audioguru,,

    tqvm
     

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  2. audioguru

    audioguru Well-Known Member Most Helpful Member

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    You forgot to ask your question about the circuits.
    What do you want to know?
     
  3. cacingidop

    cacingidop New Member

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    err,,i just want to know the operation of the circuit u have been modified,,so that i can understand it more,,maybe i can try by myself,,

    tq in advance,, :p
     
  4. dave

    Dave New Member

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  5. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The first Cmos Schmitt-trigger gate is an inverter oscillator so that the probes are fed with AC to avoid plating on them which would happen with a DC signal.
    The second and third gates produce a pulse-width-modulation output determined by the resistance (wetness) of the soil.
    The 47k resistor and 22uF capacitor smooth the PWM waveform into a variable voltage.
    the 4th gate triggers the transistor when the voltage drops to its Schmitt-trigger voltage level.
    The transistor drives the relay for the watering pump.

    The LM3914 is a voltmeter that shows the filtered variable DC voltage which shows the wetness of the soil.
     
  6. cacingidop

    cacingidop New Member

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    Tq soo much,, appreciate it~~ :p
     

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