Digital ICs Education

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

The 555 integrated circuit is the most popular chip ever manufactured. Independently manufactured by more than 10 manufacturers, still in current production, and almost 40 years old, this little circuit has withstood the test of time. It has been redesigned, improved, and reconfigured in many ways, yet the original design can be bought from many vendors. The design of this chip was right the first time. Originally conceived in 1970 and created by Hans

If the output of a shift register is fed back to the input. a ring counter results. The data pattern contained within the shift register will recirculate as long as clock pulses are applied. For example, the data pattern will repeat every four clock pulses in the figure below. However, we must load a data pattern. All 0‘s or all 1‘s doesn’t count. Is a continuous logic level from

The R/2R DAC circuit is an alternative to the binary-weighted-input (R/2nR) DAC which uses fewer unique resistor values. R/2R DAC vs. R/2nR DAC A disadvantage of the former DAC design was its requirement of several different precise input resistor values: one unique value per binary input bit. Manufacture may be simplified if there are fewer different resistor values to purchase, stock, and sort prior to assembly.

Before the advent of solid-state logic circuits, logical control systems were designed and built exclusively around electromechanical relays. Relays are far from obsolete in modern design, but have been replaced in many of their former roles as logic-level control devices, relegated most often to those applications demanding high current and/or high voltage switching. Systems and processes requiring “on/off” control abound in modern commerce and industry, but such control

Mathematicians use Venn diagrams to show the logical relationships of sets (collections of objects) to one another. Perhaps you have already seen Venn diagrams in your algebra or other mathematics studies. If you have, you may remember overlapping circles and the union and intersection of sets. We will review the overlapping circles of the Venn diagram. We will adopt the terms OR and AND instead of union and intersection since

Instrumentation is a field of study and work centering on measurement and control of physical processes. These physical processes include pressure, temperature, flow rate, and chemical consistency. An instrument is a device that measures and/or acts to control any kind of physical process. Due to the fact that electrical quantities of voltage and current are easy to measure, manipulate, and transmit over long distances, they are widely used to

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

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

It is sometimes useful in logic circuits to have a multivibrator which changes state only when certain conditions are met, regardless of its S and R input states. The conditional input is called the enable, and is symbolized by the letter E. Study the following example to see how this works: When the E=0, the outputs of the two AND gates are forced to 0, regardless of the states of either

If a pulse-width modulated (PWM) signal is sent to a passive integrator circuit from a circuit capable of both sourcing and sinking current (as is the case with the dual-MOSFET output stage), the output will be a DC voltage (with some ripple): Determine the relationship between the PWM signal’s duty cycle and the DC voltage output by the integrator. What does this suggest about PWM as a means of

So far, we’ve studied both S-R and D latch circuits with enable inputs. The latch responds to the data inputs (S-R or D) only when the enable input is activated. In many digital applications, however, it is desirable to limit the responsiveness of a latch circuit to a very short period of time instead of the entire duration that the enabling input is activated. One method of enabling a

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

Parts and Materials Multimeter, digital or analog Assorted resistors (Radio Shack catalog # 271-312 is a 500-piece assortment) Rectifying diode (1N4001 or equivalent; Radio Shack catalog # 276-1101) Cadmium Sulphide photocell (Radio Shack catalog # 276-1657) Breadboard (Radio Shack catalog # 276-174 or equivalent) Jumper wires Paper Pencil Glass of water Table salt This experiment describes how to measure the electrical resistance of several objects. You need not possess all items listed above in

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 /|||/ /|||/ /|||/ ||

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

What factors determine where potentiometers Rpot1 and Rpot2 must be set? Why are they “trimmer” potentiometers (as indicated by the special wiper symbol) and not regular panel-mount potentiometers?

One caveat with signed binary numbers is that of overflow, where the answer to an addition or subtraction problem exceeds the magnitude which can be represented with the alloted number of bits. Remember that the place of the sign bit is fixed from the beginning of the problem. With the last example problem, we used five binary bits to represent the magnitude of the number, and the left-most (sixth) bit

In an astable circuit, the output voltage alternates between VCC and 0 volts on a continuous basis.