Exercise 3, “Your First Circuit” provides the reader with the important skill of learning how to read resistor values; a good skill to have. Although one can use a DMM to determine the actual resistance value. Learning how to visually determine the the value of a resistor is sort of like a rite of passage for anyone serious about electronics as a hobby. Take that step, learn how to read the values, you’ll be better for it.
This particular circuit is also your first introduction to the LED. Some areas of focus include visually determining the positive and negative side of the LED, and how to determine both forward voltage and forward current. Note: always check electronic components to determine the manufacturers limit in respect to those forward voltages and currents. Or you’ll just waste money on parts.
The construction of this circuit is simple and should not present any difficulties. You’ll start with a 2.2k resistor, and continue to swap out different resistor values while observing the effects on the LED.
Exercise 4, “Variable Resistance“. Once again, we are tasked with sacrificing a component for the sake of science. However, as per Mr. Platt. Readers complained after the first edition of the book about not wanting to ruin a usable component. Honestly, if you take your time, you can carefully reassemble the potentiometer and it will work perfectly fine. The overall benefit of the disassembly is to get a peek inside it’s inner workings; this is one of the more interesting looking components you’ll probably come across early on. Plus, people like us, Makers, and natural born Engineers need to know how things work. Right?
The circuit in this exercise is the first time you’re in a position to actually manipulate the amount of resistance +/- in real time. The take-away here is to realize how one might damage a component by varying the resistance in the circuit. To drive the point home, you can sacrifice the LED to science as well.
Additionally, the circuit is followed up by adding a 460 ohm resistor which is used to protect the circuit in the event the potentiometer goes to zero; a fail safe.
Lastly, the reader is treated to an excellent overview of the fundamentals of Ohms law , Series and Parallel, and how to measure current in a circuit. All of which are important topics for the beginner as you take more steps toward learning electronics.
Exercise 3 Materials:
470 ohm, 1k, 2.2k resistors
Alligator Clip Test Leads
Exercise 4 Materials:
470 ohm, 1k
Potentiometer 1k linear