Decimal Counter Circuit with IC 4017

A decimal counter is an integrated circuit designed to tally the number of pulses or events occurring in digital circuits, displaying the output in decimal form, such as 1 to 99. For instance, a 12-bit counter counts 12 clock pulses or events and reflects this count at the output port. These chips retain the count of events and present it in decimal format, earning the name "decade counter." The functionality of a decade counter involves counting and storing each pulse that appears at the clock pin. Further details on its operation will be discussed in the working section.

In this setup, a 10-bit decade counter, specifically the CD4017BE chip, is utilized. With a 10-bit configuration, this counter can count events up to 10, requiring 11 clock pulses for the chip to reset itself to zero.

It's crucial to consider the working voltage and clock frequency limitations of these counters to prevent permanent damage. Careful attention must be paid when selecting the appropriate counter for the application.

Components Required

1. Power supply (5V)
2. 1K, 220Ω resistors
3. CD4017 DECADE counter IC
4. 10 LEDs
5. Connecting wires and breadboard.

Circuit Diagram and Working Explanation

The pin configuration of IC 4017 is illustrated in the figure.

Pin 13 "CLOCK ENABLE" needs to be grounded for the chip to count events or clock pulses.

Pin 12 "CARRY OUT" is for the next counter chip, connected to the next chip's clock pin for expanding the counter capacity. It can be ignored if the 10-bit count is sufficient.

The circuit initiation occurs at the clock pin, where the clock pin is pulled down to ground through a 1KΩ resistor. This is necessary as the binary counter is a rising-edge type, recognizing a positive rising edge at the clock pin as an event and incrementing the binary output by one.

A button is used to provide the clock, generating a positive peak at the clock pin for every button press, indicating an event. The DECADE counter can directly drive the LEDs, eliminating the need for resistors at the end of the binary counters' LEDs. The Master Reset (MR) of the binary counter must be pulled down at any time to avoid unpredictable LED blinking.

A capacitor is introduced to neutralize the bouncing effect of the button. Without the capacitor, the counter may incorrectly count the occurring events.

Connections for CD4017 are as follows:

• PIN 16 to +5V supply
• PIN 8, PIN 15, PIN 13 to Ground
• PIN 14 to Button
• PIN 1 to Ground through a 1k resistor
• PINS 3, 2, 4, 7, 10, 1, 5, 6, 9, 11 connected to LEDs

Every time a peak passes, the counter considers it an event and increments the output by one. Once it reaches its event tracking limit, it automatically resets to zero and recommences counting the pulses. The output provides the event number as a binary output through pins 3, 2, 4, 7, 10, 1, 5, 6, 9, 11, 12, in Least Significant Bit (LSB) to Most Significant Bit (MSB) fashion. For instance, if the event count is seven, pin "6" will be high, causing the corresponding LEDs to glow. To reset the counter to zero at any stage, connect the MR pin of the counter to +5V.