This is a breadboard. A breadboard is for making experimental model of an electric circuit. This is where the wires, resistors, transistors, and 3-8 line decoders are connected to.
A Transistor is a semiconductor device with three connections, capable of amplification in addition to rectification. Instead of buying a 2N4401 Transistor, I used the PN2222 Transistor as an alternative. Both PN2222 and 2N4401
a semiconductor device with three connections, capable of amplification in addition to rectification
The M74HC238 is a high speed CMOS 3 to 8 line decoder. There are three binary select inputs (A, B, and C) which determine which one of the eight outputs (Y0-Y7) will go high. This chip has three enable inputs (G1, ~G2A, and ~G2B); when any enable pins are brought low (or high in G1’s case), all output pins are pulled low.
This is a great tool if you need to increase the number of outputs on your micrcontroller. For example, it’s used in the 5x5x5 LED Cube to help an ATmega168 control the 125 LEDs.
The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button