CD4047 in Monostable Multivibrator Mode

2024-05-21 | By rithik krisna

Recently, I embarked on a quest to find an integrated circuit (IC) that could function as a timer. After an extensive search (and a few cups of coffee), I discovered the CD4047, a gem of an IC with a treasure trove of features. This IC not only operates as a timer but also boasts several other modes, showcasing its versatility. These additional functionalities make the CD4047 an invaluable tool for rapid prototyping, and adaptable for various applications beyond just timing. Its flexibility and ease of use streamline the development process, earning it a spot as a favorite in many electronic projects.

In this article, we’ll dive into the process of creating a timer using the CD4047 as a monostable multivibrator. Prepare to be amazed by its capabilities and ease of use!

PINOUT OF CD4047:

The pinout of the CD4047 is beautifully illustrated in the image above. The clear and easy-to-understand explanation makes it a breeze to identify and utilize each pin for various applications. This detailed diagram helps users quickly grasp the functionality and connections needed for effective use of the IC, making your project setup a walk in the park!

CIRCUIT OF MONOSTABLE MULTIVIBRATOR:

The Monostable function, true to its name, has one stable state that shifts to an unstable state when triggered externally. After a set period, it reverts to its stable state, commonly used as a timer in various applications. While modern microcontrollers offer more capabilities, the CD4047 stands out for its speed, efficiency, reliability, and cost-effectiveness for specific tasks.

Interestingly, the CD4047 offers up to four modes for Monostable Multivibrators. We'll start with the first mode: Positive Edge Trigger Mode.

The circuit diagram above illustrates the Positive Edge Trigger Mode configuration of the CD4047 IC. Key connections are as follows:

Pins 4 and 14 to +5V.
Pins 5, 6, 7, 9, and 12 to Ground.
A 1000µF capacitor between Pins 1 and 3.
A 400Ω resistor between Pins 2 and 3.
An LED with a 220Ω resistor to Pin 10 (Q).
Pin 8 (+TRIGGER) to +5V via a pushbutton and pulled down with a 10kΩ resistor.
An oscilloscope connected to Pins 8, 10 (Q output), 11 (Q‾\overline{Q}Q output), and 13 (OSC output) to observe waveforms and timing.

Ready to dive in? Let's get started!

CALCULATION OF TIME DELAY:

The timing (tM) for all modes in the Monostable Multivibrator is calculated using the formula: tM = 2.48 x R x C.

For example, with a 1000µF capacitor and a 400Ω resistor:

tM = 2.48 x 400 x 1000µF = 0.992 sec

This can be approximately considered as 1 second.

With this formula, you can easily determine the appropriate resistor and capacitor values for your specific timing needs.

LIVE DEMONSTRATION OF THE TIMER USING CD4047:

As per the circuit diagram, the connections are meticulously made as specified. Prior to implementation, the circuit underwent thorough simulation in Proteus, validating its functionality. This preemptive step ensured correct connections and performance, instilling confidence in its real-world application. The successful breadboard implementation further corroborates the design's accuracy and functionality, aligning seamlessly with the Proteus simulation results.

CONCLUSION:

As per the project requirements, I've completed the Timer Project successfully. Although we've explored several modes, there are still six more to discover. To delve deeper, we've crafted an article detailing the CD4047's Astable and Monostable Multivibrator modes. Dive into waveforms and simulation results for a comprehensive understanding. Interested in expanding your knowledge? Check out the article for valuable insights and guidance, ideal for enhancing your projects!