Electrical & Electronic Engineering

Designing With Decade Counters

A decade counter is one that goes through 10 unique output combinations and then resets as the clock proceeds further. Since it is an MOD-10 counter, it can be constructed with a minimum of four flip-flops. A four-bit counter would have 16 states. By skipping any of the six states by using some kind of [...]

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Switched Ethernet

As more and more stations are added to an Ethernet, the traffic will go up. Eventually, the LAN will saturate. One way out is to go to a higher speed, say, from 10 Mbps to 100 Mbps. But with the growth of multimedia, even a 100-Mbps or 1-Gbps Ethernet can become saturated. Fortunately, there is [...]

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Wireless LAN Protocols

As the number of mobile computing and communication devices grows, so does the demand to connect them to the outside world. Even the very first mobile telephones had the ability to connect to other telephones. The first portable computers did not have this capability, but soon afterward, modems became commonplace on notebook computers. To go [...]

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Adaptive Tree Walk Protocol

One particularly simple way of performing the necessary assignment is to use the algorithm devised by the U.S. Army for testing soldiers for syphilis during World War II (Dorfman, 1943). In short, the Army took a blood sample from N soldiers. A portion of each sample was poured into a single test tube. This mixed [...]

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Dynamic Channel Allocation

Before we get into the first of the many channel allocation methods to be discussed in this chapter, it is worthwhile carefully formulating the allocation problem. Underlying all the work done in this area are five key assumptions, described below. Station Models: The model consists of N independent stations (e.g., computers, telephones, or personal communicators), [...]

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Medium Access Control Sublayer

In any broadcast network, the key issue is how to determine who gets to use the channel when there is competition for it. To make this point clearer, consider a conference call in which six people, on six different telephones, are all connected so that each one can hear and talk to all the others. [...]

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Differential Amplifiers

For ease of drawing complex circuit diagrams, electronic amplifiers are often symbolized by a simple triangle shape, where the internal components are not individually represented. This symbology is very handy for cases where an amplifier’s construction is irrelevant to the greater function of the overall circuit, and it is worthy of familiarization: The +V and [...]

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Light Activated SCR

Like bipolar transistors, SCRs and TRIACs are also manufactured as light-sensitive devices, the action of impinging light replacing the function of triggering voltage. Optically-controlled SCRs are often known by the acronym LASCR, or Light Activated SCR. Its symbol, not surprisingly, looks like this: Optically-controlled TRIACs don’t receive the honor of having their own acronym, but [...]

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TRIAC

SCRs are unidirectional (one-way) current devices, making them useful for controlling DC only. If two SCRs are joined in back-to-back parallel fashion just like two Shockley diodes were joined together to form a DIAC, we have a new device known as the TRIAC: Because individual SCRs are more flexible to use in advanced control systems, [...]

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