PLD (Part 4)

Part 123456

Using the HL2 PLD (Place and Leave Device) is easy and usefull. We ran the earliest tests on… soil moisture. The reason why we chose this one is that I have always liked to have a green plant in my office and this one might last longer than the others. Because it is fitted with great soil moisture sensors connected to a PLD !

I am using a Capacitance-type WATERSCOUT SM100 sensor.

  • Range: 0% VWC to saturation
  • Power Requirements: 3 to 5V @ 6 to 10 mA
  • Output: Analog voltage 0.5 – 1.5V for a 3V excitation (ratiometric for other excitation voltages)
  • Resolution: 0.1% VWC
  • Cable Length: 6 ft (1.8 m) and 20 ft (6 m) standard, extendable up to 50 ft (15 m)
  • Accuracy: 3% VWC @ EC < 8 mS/cm
  • Sensing Area: 2.4 in (6 cm) x 0.8 in (2 cm)

It proved to be a very efficient, simple to use and pretty rugged sensor. The only advice that I may share here is related to the “installation” of the sensor. Water the ground, push the sensor down to the black ring and  tamped down to eliminate air gaps. This is critical regarding the reliability of the measurements.

Next is a picture of the oldest version of HL2 PLD (in grey) next to the PLD as proposed  by HL2 through the Kickstarter campaign.

Ultimately, this is a profile from the soil moisture as shown in HL2 Panorama where you can clearly see the decreasing moisture and the watering along the time.

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