The "Automatic Plant Watering Device" is a small and easy to use gadget which automatically waters your plants for you. It senses the humidity of your plant's soil, and adds water accordingly.
My starter project is the Mk. 131 Traffic Light designed by Vellman Inc. It functions as a four-way stoplight, and the duration of the lights can be changed. It is comprised of 14 resistors, 3 transistor, 5 capacitors 21 diodes, a CD4017B IC, 12 LEDs, a variable resistor, a switch and a 9V battery. The transistors, capacitors, and resistors all form to make a sort of "Clock" circuit, which sends it's information to the IC (integrated circuit), which is the brain of the circuit. The "Clock" circuit, in its most simplified form, functions by letting a resistor slow down the time it takes to charge a capacitor. The duration of the charge dictates how long the traffic lights will stay on. The IC then takes this information, and makes the LEDs light up in sequence, and for a specific amount of time. The diodes make sure the current flows in one direction. The variable resistor decides how long each light stays on, by making the capacitor take more time to charge in the "Clock" circuit. The switch turns the whole contraption on and of. And the 9V battery powers the device.