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The Transistor: A Simple Concept that Changed the World Forever by Britt Storkson Owner, P2FlowLLC Many people think the most profound inventions of the 20th and 21st centuries are something really complex, something people have spent years and years developing, resulting in reams and reams of doc- uments about the invention. Often though, the most significant inventions are the simplest ones. What is widely considered to be the most impactful invention of the 20th century? It’s the transistor. What does a transistor do that’s so great? A transistor has three terminals: the base, the collector, and the emitter. When an electrical current is applied to its base, it allows current flow from the collector to the emitter. When the base cur- rent is taken away, the current flow stops. (See illustration.) It can “switch” the current flow on and off. This is all it does. It doesn’t seem like much, but it’s a really big deal. Transistors are much faster than me- chanical switches. Basically, transistors don’t wear out. Often, they are much less expensive than mechanical switches. Like everything, they do have limitations and must be selected to service the application for good performance and maximum life, but transistors are not going away anytime soon. They’re that good. The word “transistor” is derived from two words: “trans” = moving . . . like the word trans- portation . . . and “istor” which is the tail end of the word “resistor”. A transistor is a moving electrical resistance. It can either be a very low resistance (but never zero) or a very high re- sistance depending on the amount of current applied to the base. This makes it possible to do all sorts of things. Transistors have many applications, and detailing everything a transistor can do is beyond the scope of this article. However, one major application for a transistor is amplification. A small current at the base of the transistor controls a much larger current flowing from the collector to the emitter. Small currents applied to the transistor base can control much larger currents (or voltages) flowing from the emitter to the collector. The concept is much like a small rudder controlling a big ship, or a small bridle and bit controlling a large horse. Small changes in the control end can result in big changes in the operational end. There are many advantages to this kind of operation. With the microprocessors I use, I can do all of the computational op- erations using very small amperages . . . like micro (millionths) or nano (billionths) of an ampere and, when I’m ready to output the result, output to the base of a tran- sistor which dr ives a much higher amperage device like a light or a motor. The reason for this, like most every- thing we do in industry, is cost. Low- amperage transistors cost less to make than high-amperage transistors. To keep the product cost low, we use only the mate- rial needed to get the job done. So if you have a low-amperage application, you use a low-amperage transistor; likewise, if you want to control a higher amperage, you use a transistor capable of doing it. It’s a good practice with any product development to closely match the com- ponents to the application they are to service. One should not overbuild things and add to the cost, and likewise, one should not underbuild things as this would reduce product performance and relia- bility. The result is a product which is ade- quately reliable, but not overly costly for the customer, as well as profitable to manufacture. Britt Britt Storkson may be contacted via e-mail to michele@ worldwidedrillingresource.com 16 MARCH 2018 WorldWide Drilling Resource ®