Circuit Equipments

In this whole week, I have being learned on circuit making on the website. This is so helpful for me! Those tutorials are useful and details.

http://extremeelectronics.co.in/avr-tutorials/part-v-digital-io-in-avrs/

I found that what main Circuit Equipments I need to build my own circuit. I think I need:

Distance Sensor: check sth pass through from a such distance

Variable Resistor: control the level of power of the circuit by produce resistance

Mircocontollor: control the circuit by programming input

Op-amp: control the voltage of the circuit