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Kemo 12V Soil Humidity Sensor

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Quoting product code: A32JU


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About this product


  • Helps you to control soil humidity in gardens, fields and grassed areas
  • Monitors soil humidity in deeper layers
  • Can be used to switch on/off a spray-irrigation system when soil becomes too dry

Product overview

• Helps you to control soil humidity in gardens, fields and grassed areas• Monitors soil humidity in deeper layers • Can be used to switch on/off a spray-irrigation system when soil becomes too dry• Sensitivity can be adjusted to low or high soil humidity• Quick and easy installation• Can be combined with a timer for watering the garden on special days or automatically when dry• The "must have" for people who care about their gardens!

This sensor can be used to switch on your garden irrigation pump or the magnetic valve when the soil is dry and switch it off when there is enough humidity in the soil. The measuring head has to be buried into the ground at the depth where it shall measure and is connected to the main sensor unit via a 2m cable. The sensor cable may be extended up to 20m with normal 2-pole cable. The device is operated by means of a commercial plug power supply (Regulated 12V at >130mA with standard 3.5mm plug - Order Code: L47BL). The main module should be mounted in a weatherproof location. If required, the garden can be irrigated at certain times of the day or weekdays only, by using a suitable mains timer. The soil humidity sensor starts to operate when it receives current from the power supply in the following sequence:1) The soil humidity is measured after switching on the operating voltage.2) The connected pump is switched on for 18...30 minutes if the soil is too dry.3) If the soil is humid enough the device switches to "Pause" for about 18...30 minutes and makes a new measurement after that.This sequence continues in an infinite loop until the operating voltage is switched off.

Rated 3 out of 5 by from Pay attention to the detail when purchasing this. The DC power supply is via a 3.5mm Jack Plug. This is non-standard for the UK as normally AC/DC Adaptors here have a DC Power Plug (with the flat end). Maplin do not have a plug adaptor for DC Power to Jack as far as I can see. Maplin solution to this is to offer an AC/DC Adaptor with various adaptor plugs including the 3.5mm Jack Plug (L47BL). If like me you probably have lots of 12V Adaptors lying around so just buy a Plastic 3.5mm Mono Plug (HF80B) for Ј1.29 cut off DC Power Plug and replace with 3.5mm Jack Plug making sure positive is to the plug end. Note if you insert a 3.5mm DC Power Plug into unit the Red LED glows which is misleading as you can think it is working. It is not. Inserting the Jack Plug will light the Green LED even if the sensor is not connected (a good check) Another point to note is that the cover of the unit is fixed with four screws from the back. This means if you want to adjust the potentiometer (more anti-clockwise triggers the relay the drier the conditions) you have to dismount the whole unit to access the controller. Once over the above it seems to work fine
Date published: 2012-08-21
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Switching contact: 1 x 3A max, screw terminal connections
Sensor housing dimensions: 30mm (dia) x 64mm (l)
Galvanised pins dimensions: 4mm (dia) x 40mm (l)