Digital ICs Education

A serial-in, parallel-out shift register is similar to the serial-in, serial-out shift register in that it shifts data into internal storage elements and shifts data out at the serial-out, data-out, pin. It is different in that it makes all the internal stages available as outputs. Therefore, a serial-in, parallel-out shift register converts data from serial format to parallel format. An Example of Using Serial-in, Parallel-out Shift Register If four data

Try out our 555 Timer Astable Circuit in our Tools section. PARTS AND MATERIALS One 9V Battery Battery Clip (Radio Shack catalog # 270-325) Mini Hook Clips (soldered to Battery Clip, Radio Shack catalog # 270-372) U1 - 555 timer IC (Radio Shack catalog # 276-1723) D1 - Red light-emitting diode (Radio Shack catalog # 276-041 or equivalent) D2 - Green light-emitting diode (Radio Shack catalog # 276-022 or equivalent) R1,R2 - 1 KΩ 1/4W Resistors R3

The Commutative Property Another type of mathematical identity, called a “property” or a “law,” describes how differing variables relate to each other in a system of numbers. One of these properties is known as the commutative property, and it applies equally to addition and multiplication. In essence, the commutative property tells us we can reverse the order of variables that are either added together or multiplied together without changing the

The term “combinational” comes to us from mathematics. In mathematics a combination is an unordered set, which is a formal way to say that nobody cares which order the items came in. Most games work this way, if you rolled dice one at a time and get a 2 followed by a 3 it is the same as if you had rolled a 3 followed by a 2. With combinational logic, the circuit produces

Since the enable input on a gated S-R latch provides a way to latch the Q and not-Q outputs without regard to the status of S or R, we can eliminate one of those inputs to create a multivibrator latch circuit with no “illegal” input states. Such a circuit is called a D latch, and its internal logic looks like this: Note that the R input has been replaced with

When we store information in some kind of circuit or device, we not only need some way to store and retrieve it, but also to locate precisely where in the device that it is. Most, if not all, memory devices can be thought of as a series of mail boxes, folders in a file cabinet, or some other metaphor where information can be located in a variety of places. When

If we were to connect two inverter gates together so that the output of one fed into the input of another, the two inversion functions would “cancel” each other out so that there would be no inversion from input to final output: While this may seem like a pointless thing to do, it does have practical application. Remember that gate circuits are signal amplifiers, regardless of what logic function they

Don’t just sit there! Build something!! Learning to mathematically analyze circuits requires much study and practice. Typically, students practice by working through lots of sample problems and checking their answers against those provided by the textbook or the instructor. While this is good, there is a much better way. You will learn much more by actually building and analyzing real circuits, letting your test equipment provide the “answers” instead

In section 15.1, and we'll converting binary to decimal, decimal to binary and binary to hex in this particular section. We alluded to this in the first section, but we will review of parts of it again. It is important to be able to convert binary numbers to their decimal equivalent. To convert a binary number to its equivalent decimal value, multiple the weight of each column by the digit value

The logic simplification examples that we have done so far could have been performed with Boolean algebra about as quickly. Real world logic simplification problems call for larger Karnaugh maps so that we may do serious work. We will work some contrived examples in this section, leaving most of the real world applications for the Combinatorial Logic chapter. By contrived, we mean examples which illustrate techniques. This approach will develop

For reference, this section introduces the terminology used in some texts to describe the minterms and maxterms assigned to a Karnaugh map. Otherwise, there is no new material here. Σ (sigma) indicates sum and lower case “m” indicates minterms. Σm indicates sum of minterms. The following example is revisited to illustrate our point. Instead of a Boolean equation description of unsimplified logic, we list the minterms. f(A,B,C,D) = Σ

PARTS AND MATERIALS Two AAA Batteries Battery Clip (Radio Shack catalog # 270-398B) A DVM or VOM U1 - CMOS TLC555 timer IC (Radio Shack catalog # 276-1718 or equivalent) Q1 - 2N3906 PNP Transistor (Radio Shack catalog #276-1604 (15 pack) or equivalent) Q2 - 2N2222 NPN Transistor (Radio Shack catalog #276-1617 (15 pack) or equivalent) D1 - Red light-emitting diode (Radio Shack catalog # 276-041 or equivalent) R1 - 1.5 MΩ 1/4W 5% Resistor R2

We can subtract one binary number from another by using the standard techniques adapted for decimal numbers (subtraction of each bit pair, right to left, “borrowing” as needed from bits to the left). However, if we can leverage the already familiar (and easier) technique of binary addition to subtract, that would be better. As we just learned, we can represent negative binary numbers by using the “two’s complement” method

PARTS AND MATERIALS 555 timer IC (Radio Shack catalog # 276-1723) One 1N914 “switching” diode (Radio Shack catalog # 276-1122) Two 10 kΩ resistors One 100 µF capacitor (Radio Shack catalog # 272-1028) 4027 dual J-K flip-flop (Radio Shack catalog # 900-4394) Ten-segment bargraph LED (Radio Shack catalog # 276-081) Three 470 Ω resistors One 6 volt battery Caution! The 4027 IC is CMOS, and therefore sensitive to static electricity! CROSS-REFERENCES Lessons In Electric Circuits, Volume 4, chapter 10: “Multivibrators” Lessons In Electric Circuits, Volume 4,

Knowing how to generate Gray code should allow us to build larger maps. Actually, all we need to do is look at the left to right sequence across the top of the 3-variable map, and copy it down the left side of the 4-variable map. See below. Reductions of 4 Variable K Maps The following four variable Karnaugh maps illustrate the reduction of Boolean expressions too tedious for Boolean algebra. Reductions

PARTS AND MATERIALS 4011 quad NAND gate (Radio Shack catalog # 276-2411) Eight-position DIP switch (Radio Shack catalog # 275-1301) Ten-segment bar graph LED (Radio Shack catalog # 276-081) One 6 volt battery Three 10 kΩ resistors Two 470 Ω resistors Caution! The 4011 IC is CMOS, and therefore sensitive to static electricity! CROSS-REFERENCES Lessons In Electric Circuits, Volume 4, chapter 3: “Logic Gates” Lessons In Electric Circuits, Volume 4, chapter 10: “Multivibrators” LEARNING OBJECTIVES Principle and function of an enabled latch circuit

The half-adder is extremely useful until you want to add more that one binary digit quantities. The slow way to develop a two binary digit adders would be to make a truth table and reduce it. Then when you decide to make a three binary digit adder, do it again. Then when you decide to make a four digit adder, do it again. Then when ... The circuits would be fast,

Identify each of these logic gates by name, and complete their respective truth tables:

What does the normal status of an electrical switch refer to? Specifically, what is the difference between a normally-open switch and a normally-closed switch?

Diodes can perform switching and digital logic operations. Forward and reverse bias switch a diode between the low and high impedance states, respectively. Thus, it serves as a switch. Logic Diodes can perform digital logic functions: AND, and OR. Diode logic was used in early digital computers. It only finds limited application today. Sometimes it is convenient to fashion a single logic gate from a few diodes. Diode AND gate