Plant Tester

Do you ever wonder if you plant has enough water? Well I do and so I created this super simple circuit to help.

For this project you will need a 9v battery, 9v battery clip, tiny breadboard, one LED of any color, 220 ohm resistor, wire, diode, wire strippers, and needle nose pliers. ( below are links to all of the supplies you will need if you don't have them)

Components:

9v battery

9v battery clip

Tiny breadboard

LED’s

220 ohm resistors

Diode

Wire

Tools:

wire strippers

needle nose pliers

lets make our probes. this is what we stick into the soil to see if it is wet or dry.

• First, strip off about 1/4 inch of insulation off on side of the wire
• Then, strip off 4-5 inches of insulation on the other side
• Next, do the same thing to the other side
• Finally, tape the wires together close to the bottom. then bend the wires if you would like

Now we have to wire our circuit.

• First, plug in the probes to the corner of the breadboard
• Then, plug in your NPN transistor (bump facing away from the probes)
• Next, plug in you resistor at the far end of the transistor and then the positive wire at the far end of the breadboard and then the diode ( the grey band should be facing away from the red wire )
• Then, plug in the positive wire of the battery clip into the breadboard
• Next, plug in the positive side of the led to the other side of the transistor
• Finally, plug in the negative side of the LED to the negative wire of the battery clip

Now that we wired our circuit we now can securely mount our battery with some tape as shown in the picture

• tape the battery to the bottom of the breadboard

Now that we are done lets test it.

This works because the transistor acts as a switch so when the soil is dry there is high resistance so the LED does not turn on but, when the soil is wet or damp there is not much resistance so the LED will turn on.