Digital ICs Education

Up to this point we have considered logic reduction problems where the input conditions were completely specified. That is, a 3-variable truth table or Karnaugh map had 2n = 23 or 8-entries, a full table or map. It is not always necessary to fill in the complete truth table for some real-world problems. We may have a choice to not fill in the complete table. For example, when dealing with BCD (Binary

PARTS AND MATERIALS 4017 decade counter/divider (Radio Shack catalog # 276-2417) 555 timer IC (Radio Shack catalog # 276-1723) Ten-segment bargraph LED (Radio Shack catalog # 276-081) One SPST switch One 6 volt battery 10 kΩ resistor 1 MΩ resistor 0.1 µF capacitor (Radio Shack catalog # 272-135 or equivalent) Coupling capacitor, 0.047 to 0.001 µF Ten 470 Ω resistors Audio detector with headphones Caution! The 4017 IC is CMOS, and therefore sensitive to static electricity! Any single-pole, single-throw switch is adequate. A household

What is the purpose of a seven-segment decoder circuit? What is a “seven-segment” display, and why do we need a decoder circuit to drive it? Research the part number for a typical seven-segment decoder circuit (either CMOS or TTL).

A mathematician named DeMorgan developed a pair of important rules regarding group complementation in Boolean algebra. By group complementation, I’m referring to the complement of a group of terms, represented by a long bar over more than one variable. You should recall from the chapter on logic gates that inverting all inputs to a gate reverses that gate’s essential function from AND to OR, or vice versa, and

Suppose we wanted to build a device that could add two binary bits together. Such a device is known as a half-adder, and its gate circuit looks like this: The Σ symbol represents the “sum” output of the half-adder, the sum’s least significant bit (LSB). Cout represents the “carry” output of the half-adder, the sum’s most significant bit (MSB). If we were to implement this same function in ladder

What does it mean, in general terms, to encode something? Conversely, what does it mean to decode something? Perhaps the most common context for these terms to be used is cryptography (code-making and code-breaking), but they also find application in common digital circuits.

In designing digital circuits, the designer often begins with a truth table describing what the circuit should do. The design task is largely to determine what type of circuit will perform the function described in the truth table. While some people seem to have a natural ability to look at a truth table and immediately envision the necessary logic gate or relay logic circuitry for the task, there are procedural

What is a Synchronous Counter? A synchronous counter, in contrast to an asynchronous counter, is one whose output bits change state simultaneously, with no ripple. The only way we can build such a counter circuit from J-K flip-flops is to connect all the clock inputs together, so that each and every flip-flop receives the exact same clock pulse at the exact same time: Now, the question is, what do we

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

Although the prime intent of octal and hexadecimal numeration systems is for the “shorthand” representation of binary numbers in digital electronics, we sometimes have the need to convert from either of those systems to decimal form. Of course, we could simply convert the hexadecimal or octal format to binary, then convert from binary to decimal, since we already know how to do both, but we can also convert directly. Because

One of the more advanced ADC technologies is the so-called delta-sigma, or ΔΣ (using the proper Greek letter notation). In mathematics and physics, the capital Greek letter delta (Δ) represents difference or change, while the capital letter sigma (Σ) represents summation: the adding of multiple terms together. Sometimes this converter is referred to by the same Greek letters in reverse order: sigma-delta, or ΣΔ. In a ΔΣ converter, the analog input voltage signal is connected

Up to now, every circuit that was presented was a combinatorial circuit. That means that its output is dependent only by its current inputs. Previous inputs for that type of circuits have no effect on the output. However, there are many applications where there is a need for our circuits to have “memory”; to remember previous inputs and calculate their outputs according to them. A circuit whose output depends not

Let’s count from zero to twenty using four different kinds of numeration systems: hash marks, Roman numerals, decimal, and binary: System: Hash Marks Roman Decimal Binary ------- ---------- ----- ------- ------ Zero n/a n/a 0 0 One | I 1 1 Two || II 2 10 Three ||| III 3 11 Four |||| IV 4 100 Five /|||/ V 5 101 Six /|||/ | VI 6 110 Seven /|||/ || VII 7 111 Eight /|||/ ||| VIII 8 1000 Nine /|||/ |||| IX 9 1001 Ten /|||/ /|||/ X 10 1010 Eleven /|||/ /|||/ | XI 11 1011 Twelve /|||/ /|||/ || XII 12 1100 Thirteen /|||/ /|||/ ||| XIII 13 1101 Fourteen /|||/ /|||/ |||| XIV 14 1110 Fifteen /|||/ /|||/ /|||/ XV 15 1111 Sixteen /|||/ /|||/ /|||/ | XVI 16 10000 Seventeen /|||/ /|||/ /|||/ ||

The single-transistor inverter circuit illustrated earlier is actually too crude to be of practical use as a gate. Real inverter circuits contain more than one transistor to maximize voltage gain (so as to ensure that the final output transistor is either in full cutoff or full saturation), and other components designed to reduce the chance of accidental damage. Shown here is a schematic diagram for a real inverter circuit, complete

Hey we are in 15-3 and in this section we are going to be looking at sequential logic. This section will actually be broken into multiple sections. A sequential logic circuit can have any number of inputs and any number of outputs. Now this is much like what we discussed in combinational logic. A sequential logic circuit typically has some type of memory element to hold the state of the

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?

PARTS AND MATERIALS Two AAA Batteries Battery Clip (Radio Shack catalog # 270-398B) U1 - 1CMOS 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) CR1 - 1N914 Diode (Radio Shack catalog #276-1122 (10 pack) or equivalent, see Instructions) D1 - Blue light-emitting diode (Radio Shack catalog # 27

A practical application of switch and relay logic is in control systems where several process conditions have to be met before a piece of equipment is allowed to start. A good example of this is burner control for large combustion furnaces. In order for the burners in a large furnace to be started safely, the control system requests “permission” from several process switches, including high and low fuel pressure, air

Perhaps the most important consideration of an ADC is its resolution. Resolution is the number of binary bits output by the converter. Because ADC circuits take in an analog signal, which is continuously variable, and resolve it into one of many discrete steps, it is important to know how many of these steps there are in total. For example, an ADC with a 10-bit output can represent up to 1024 (210) unique

Suppose we altered our basic open-collector inverter circuit, adding a second input terminal just like the first: This schematic illustrates a real circuit, but it isn’t called a “two-input inverter.” Through analysis, we will discover what this Circuit’s logic function is and correspondingly what it should be designated as. Just as in the case of the inverter and buffer, the “steering” diode cluster marked “Q1” is actually formed