I have a plant that I want to automatically water. I have a plan to buy a small fountain pump which plugs into a wall. I am also going to build a small soil moisture sensor to see if the soil is dry. I want to find a simple way to let power go through the wall outlet to the pump once the sensor circuit is broken from the soil dryness. I am only 12 years old and I don't have a soldering iron so please help me find a way to make a circuit to water my plant. Thanks!
For something that a 12 year old budding engineer can work with, how about using an off-the-shelf wireless remote outlet like this $10 one from Amazon and hack the remote control instead of dealing with the AC power directly.
Try it out on your fountain pump. Then you can see if you can make an electronic circuit (transistors and opamps) or computer circuit (Arduino, Rasperry Pi, etc) to read the moisture sensor and control the remote control.
You can either electrically simulate the button presses or you can use one or two servos to physically press the ON and OFF buttons on the remote.
I hope this points you in a good and useful direction for your design. -Vince