Update 2011-09-05: I have created a new blog about electronics only – check it out here: Electronic measurements, NSLU2 and soil moisture sensor
This is my new homemade soil temperature sensor with a DS18S20 IC. The sensor is in the top of the picture. The left cable is coming from the NSLU2 computer and the right cable continues up to the air temperature sensor, which is also a DS18S20 IC. So now there are two IC’s on my 1-wire network using Cat5e Ethernet cable. The black tube on the left cable is just a collection of unused wires coming from the computer. These are required for other IC’s which will be added to the network later. The DS18S20 is glued onto a 20 x 20 cm (8 x 8 inch) aluminium plate to get good thermal contact to the soil.