The circuit

Building the circuit

In this section the components are soldered onto the pre-drilled PCB board. The photo to the left shows the part of the circuit which goes into the soil, and where all the components are soldered into. This side of the board has tracks of wire etched on to it and they conduct the current around the circuit.

The photo above and to the right shows the components soldered onto the PCB, note there is no solder on this side.

In order to make the battery clip more secure in the PCB a 1.5mm hole is drilled and the red and black wires are fed through and soldered.  The reason for drilling these hosles is so that the battery clip is more secure and should not pull out as easily.  The wires will pull out if you have a battery pluged into the clip and it is hanging as you carry the circuit around the room, so be careful and do not let this happen.

When you are making this project all the components are located in one box. When all the components are soldered onto the PCB the extra leads need to be cut off, as you can see from the photograph these leads are not needed and can be dangerous and are sharp.

How the circuit works

When the circuit is inserted into the soil it will detect if there is any moisture in the soil by turning on the Light Emitting Diode (LED). If the LED does not come on then there is no moisture in the soil and you need to water your plants.

When building the circuit a number of tools are needed.

These include

Long nose pliers, these are both cutting and gripping pliers used by electricians and other tradesmen to bend, re-position and cut wire. Their namesake long gripping nose provides excellent control and reach for fine work in small or crowded electrical enclosures, while cutting edges nearer the pliers’ joint provide “one-tool” convenience. Given their long shape, they are useful for reaching into cavities where cables (or other materials) have become stuck or unreachable to fingers or other means.

Side cutters, these are used to cut the wire at the correct length, and,

a tool to remove the plastic insulating wire from outside of the wire connecting the components together.

The wire used in building this circuit is made up of two sections: – The insulating material, which is the plastic outside, this material does not allow electricity to pass through it, and the conductor wire which is the material inside the plastic that allows the electricity to pass through it.