Sharing Current Explained
The wires share positive prong which makes the lights dimmer but when you pull out a certain wire only one uses the+wire it gets brighter
Voltage dividing in between resistors
When electricity goes through one resistor it now has a choice of either going through the LED or going through the wire into another resistor, which divides the electricity in two and the LED gets less of it.
How the DAC circuit works
Ok. So. When the rightmost switch is on, it slowly drains down as it goes to the buzzer, powering the buzzer the least. When the two rightmost switches are on, more current gets to the buzzer, and it makes a louder noise. When all four are on, it makes the loudest noise, because there is the most amount of current getting to the buzzer. There are 16 different volumes in total depending on which switches are on or off.
What is the bus part of the breadboard?
The top bus line is all connected together. The bottom line buses are all connected. The two buses are not connected to each other.
How the PNP makes the motor spin
When the button is not pressed, then electric current can get to the middle pin of the PNP, thus blocking any electricity coming from the blue wire and causing the fan to stay off. However, when the button is on, the electricity coming from the blue wire can get through to power the motor, because the PNP is now switched on.
How does the addition of the NPN transistor work?
The base pin of the NPN transistor is powered when the IR LED is turned on. This closes the visible LED's circuit with the battery and resistor, turning it on.