electronics

Synchronous Counters Each of the counter circuits described so far has been a non-synchronous or ripple counter. Each flip-flop, other than FFA, cannot change state until the preceding flip-flop has changed state from 1 to 0, An input pulse appears to ‘ripple’ through the circuit and there is a cumulative delay in operation. Faster operation […]
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Non-synchronous Counters Divide-by-2 Counter Two ways of obtaining a divide-by-two counter are shown by Figs .10(a) and (b). The J-K flip-flop circuit in (a) has both its J and K inputs held permanently at logical 1. The circuit toggles at the end of each clock pulse and generates an output pulse waveform at one-half the […]
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Sequential Digital Circuits flip-flop A sequential logic circuit is one that is able to store one bit, or more, of data and whose output depends on both stored data and new input data. The basic sequential logic circuit is the flip-flop. A flip-flop is a circuit which has two stable states: either it is SET, […]
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Logic Circuits That Meet a Given Specification 1. A machine is to start working only when a start button is pushed by an operator (A), OR a start signal is received from a control point (BJ, AND a protective guard is in place (C) AND the piece to be machined is in position (D). The […]
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The Karnaugh map is a graphical representation of all the combinations of the input variables that can exist in a logical circuit. The map consists of a number of squares, each of which represents a unique combination of the input variables. The number of squares in a map must be equal to 2n, where n […]
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Design Many digital circuits consist of a number of gates which have been interconnected to perform a wanted logical function. The design of a combinational logic circuit starts with the truth table which describes the required logical operation. Once the truth table has been written down it can be used to derive the Boolean expression […]
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Analysis Of Combination Logic Circuit The function of an existing combination logic circuit is expressed by the Boolean equation that describes the signal that appears at its output terminal(s). The output function can be determined by following through the circuit the output of each gate as it is connected to the inputs of one or […]
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Combinations of Gates Very often it is convenient to be able to perform a logical function using a different kind of gate. AND Followed by NOT If an AND gate is followed by a NOT gate (see Fig.12) the output of the circuit will be . Therefore, the combination acts like a NAND gate.   […]
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The NAND Gate The NAND gate. Fig .6, performs the inverse logical function to the AND gate. The output of a NAND gate is at 0 only if all of the inputs to the gate are at 1. The truth table of 2-input and 3-input NAND gates are given by Table 8,6. The Boolean expressions […]
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Combinational Digital Circuits Modem electronics make ever increasing use of digital electronic circuitry which responds only to signals that can only take up either one of two logic levels. Either the signal is HIGH or it is LOW. In most circuits the HIGH state is used to represent binary 1 while the LOW state represents […]
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