Electronics at 100 MPH
You bought this book to learn to program using Python and to learn about the Raspberry Pi. You also want to build some cool projects, learn how the Pi runs Linux, and learn how you can use Python to interface with the Pi and various add-ons.
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Electronics at 100 MPH You bought this book to learn to program using Python and to learn about the Raspberry Pi. You also want to build some cool projects, learn how the Pi runs Linux, and learn how you can use Python to interface with the Pi and various add-ons. Well, we’re going to get to that, but before we do I need to explain some other essential prerequisites—namely, the rules of electronics and electricity, tools, safety rules, and some how-tos. They may not be the most sexy topics, but any book that deals with building electronics projects should have at least one chapter that deals with concepts like Ohm’s Law and How to Solder and the fact that, yes, it’s entirely possible to electrocute yourself with a 9V battery. (See sidebar.) Not to mention, I wouldn’t want my readers to suffer any bodily injury because I didn’t do enough safety instruction. So, please, at least skim this chapter and take some notes if this information is completely new to you. If you finish the chapter and feel the need to protect yourself by dressing in a manner similar to Figure 4-1, that is perfectly all right.
© Wolfram Donat 2018 W. Donat, Learn Raspberry Pi Programming with Python, https://doi.org/10.1007/978-1-4842-3769-4_4
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Figure 4-1. Possible lab safety outfit THE DARWIN AWARDS If you’re not aware of them already, the Darwin Awards are humorous awards bestowed yearly upon those members of the human race who have managed to remove themselves from the gene pool, either through death or sterilization, due to their own stupidity. Past winners have included thieves who electrocuted themselves while stealing copper wire from electrical substations, drivers who switched places with their passengers while driving at highway speeds, and drug users who injected poppy seeds into their veins.
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The 9V battery electrocution incident took place when a Navy sailor, in an attempt to measure his body’s electrical resistance, stuck the pointed probes of his 9V multimeter into his thumbs, making his blood a perfect conductor. The current traveled across his heart, disrupting his heartbeat and killing him. You can read more about the Darwin Awards at their website: www.darwinawards.com.
Basic Electricity Concepts . . . and he spake, and spake thusly: “There shall be one law, and that law is of Ohm, and it is that V is equal to I times R.” OK, I know this quote is somewhat cheesy; however, Ohm’s Law is indeed the first thing any electrical engineering student learns, and it affects everything you do in electronics. It means that the total voltage (V; measured in volts) at any point in a circuit is equal to the product of the current (I; measured in amps) times the resistance (R; measured in ohms). The I stands for Inductance, which is why it’s an I, not a C. So, if you have a 200-ohm resistor that has 0.045 amps moving through it, the voltage across that resistor is equal to 9 volts. Like any good algebraic equation, it’s interchangeable: V = I × R I = V ÷ R R
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