Chapter 3. How to build circuits
This chapter covers
- Using Ohm’s law to manipulate voltage, current, and resistance in a circuit
- Prototyping basic circuits on breadboards
- The difference between parallel and series circuits
- Nitty-gritty details about LEDs and how to wire them up in several useful configurations
- Identifying and selecting the right resistor for different circuits and components
- Calculating the resistance in a series circuit and a parallel circuit
For this chapter, you’ll need
- 1 Arduino Uno
- 4 standard LEDs, red
- 4 220 V resistors
- 4 560 V resistors
- 1 100 V resistor
- 1 push-button switch
- 1 9 V battery
- 1 9 V battery snap
- 5 red and two black jumper wires
- 1 half-size breadboard
Designing and building circuits may be completely new to you, and may seem intimidating. The good news is that there are just a handful of core concepts to wrap your head around. Once you understand the interplay of voltage, current, and resistance—as formalized in Ohm’s law—you’re well on your way to being able to understand basic circuits.
There are a couple of metaphors traditionally used to illustrate voltage, current, and resistance. The most common analogy is a hydraulic (water) system involving tanks and pipes. Effective, but not always memorable. Let’s try a different adventure.