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Counter (pack of 1) £3.19

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Decade Counter IC SN74LS92N

The 7492 is a four-bit ripple counter that has a divide-by-2 section and a divided-by-6 section.

Design of Divide-by-N Counters

A counter can also be used as a frequency divider. Each flip-flop will divide its input signal by 2 such that the output of the last stage will be a frequency equal to the input frequency divided by the Modulus number. A counter with any Modulus number can be formed by using an external gate to reset the counter at a predetermined number. The logic gate is used to decode the binary equivalent of the MOD number. For a MOD-5 counter, the NAND gate must decode state 101. The decoder can be used to preset some of the flip-flops as well as reset the flip-flops. This means that the count sequence will start at some state other then zero. An enable gate (2-input AND gate) can be used to stop a counter when its final state is reached.

System Design Applications

The IC counters can be cascaded together to get larger MOD numbers. Any special state of a counter can be decoded to light an LED, sound a buzzer, operate a relay or any other external function. Several 7490s can be cascaded together to form BCD counters.

Tech Tin Files: Digital counter chips (short story)

  • In digital logic and computing, a counter is a device which stores (and sometimes displays) the number of times a particular event or process has occurred, often in relationship to a clock signal. The most common type is a sequential digital logic circuit with an input line called the "clock" and multiple output lines. The values on the output lines represent a number in the binary or BCD number system. Each pulse applied to the clock input increments or decrements the number in the counter.
  • A counter circuit is usually constructed of a number of flip-flops connected in cascade. Counters are a very widely-used component in digital circuits, and are manufactured as separate integrated circuits and also incorporated as parts of larger integrated circuits.
  • A decade counter is one that counts in decimal digits, rather than binary. A decade counter may have each (that is, it may count in binary-coded decimal, as the 7490 integrated circuit did) or other binary encodings. "A decade counter is a binary counter that is designed to count to 1010b (decimal 10). An ordinary four-stage counter can be easily modified to a decade counter by adding a NAND gate.