Alright folks, this is the good one. Transistors are the backbone of the modern world. Arguably, the single most important invention of the 20th century. I would challenge anyone to find a single complex (or even simple) electronic device that doesn’t use this component. Master it and take one step closer to walking on the proverbial water. So let’s get started on this chapter.


So before we get to deep into this let me preface with I was only able to complete one of the two examples. I only had one of the two transistors needed to complete it. I ordered more but it didn’t come in during the week and I couldn’t hold out any longer if I wanted to finish this book. I will update this post when the rest of the transistors come in.


Once again this lesson does an excellent job watering down complex topics into a very consumable chunk. As I eluded earlier, transistors are the workhorse of our world. They are, in the end though, nothing more than an electronic switch.  With their three terminals, they are able to switch on the flow of current to a device with relatively low voltage.


There are many different transistors on the market but in the end they boil down to one of two types. NPN transistors (the one pictured in my example) is a normally open transistor. You must apply power to it’s center terminal in order to open the flood gate of power (or close the circuit). The second type is PNP which you can probably infer is a normally closed transistor. You apply power to the middle terminal in order to open the circuit.



As you can see in this image, the battery is attached but the LED is not illuminated. It will not turn on, and the capacitor will not charge, until the button is pushed. This is the first example given in the book with the NPN transistor.


Some things to note here. Make sure you have a diode attached on your positive terminal. This will prevent current from flowing in the incorrect direction. Transistors are very sensitive to current flow so if you screw it up you’ll be needing another.




The main things to take away from this lesson are how transistors actually work, the difference between NPN and PNP, and finally the different terminals and how to identify them.


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This lesson is a little light on the history of transistors and why they are so important so I would do some extra reading on them. You can start with the Transistor Wiki article here


There is also another really great set of images that show how basic transistors are used for logic gates. If you don’t know what logic gates are look at your cell phone. You’re holding about a billion of them in your hand. Current day processors are made of billions of transistors that make up logic gates of AND OR and NOT. Here are three images that show how they are constructed with transistors. 


Finally I leave you with this. It took me no less than 5 tries to get this one to work. I’m not sure if it was due to my lack of understanding of how these components work or if it was because I was using a tiny little bread board. However, you can see from the gif that I did manage to get it up and running. I did have to use a larger bread board to do it but I did get it up and running.


Stick with it until you get it to work because the payoff for this one is pretty cool.


Author: Anthony Russell

Professional .NET developer

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