Monostable Multivibrator Using CD4047

Recently, I delved into finding an integrated circuit (IC) capable of functioning as a timer. During my extensive search, I came across the CD4047, an exceptional IC with a wide range of features. This IC is not only capable of operating as a timer but also includes several other modes, enhancing its versatility. These additional functionalities make the CD4047 an invaluable tool for rapid prototyping, as it can be adapted for various applications beyond just timing. Its flexibility and ease of use significantly streamline the development process, making it a preferred choice for many electronic projects.

In this article, we will be covering the process of making a timer using CD4047 as a monostable Multivibrator

CD4047 IC - 1

Bread Board - 1

Jumper Wires - Required

Resistor and Capacitors as per the required value

The pinout of the CD4047 was illustrated in the above image. The explanation provided is clear and easy to understand, making it straightforward to identify and utilize each pin for various applications. The detailed diagram helps users quickly grasp the functionality and connections needed for effective use of the IC.

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

Actually, there are up to 4 modes for Monostable Multivibrators in the CD4047. So we will utilize the first Mode Positive Edge Trigger Mode.

The circuit diagram given above shows 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‾​ output), and 13 (OSC output) to observe waveforms and timing.

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

For instance, with a capacitor of 1000µF and a resistor of 400Ω: tM=2.48×400×1000µF=0.992 sec

This can be approximately considered as 1 second.

With this, you can identify the Resistor and Capacitor values.

According to the circuit diagram, the connections are made as specified. This circuit has also been thoroughly verified by simulating it in Proteus beforehand. The simulation in Proteus ensured that all connections were correct and the circuit functions as intended, providing confidence in its real-world performance. By simulating the circuit first, we were able to identify and correct any potential issues, ensuring the reliability and accuracy of the final design.

The connected circuit on the breadboard also works as intended. This successful breadboard implementation confirms the accuracy and functionality of the design, consistent with the earlier Proteus simulation.

As per the project requirements, I have successfully completed the Timer Project. As previously mentioned, there are still six modes to explore. To provide a comprehensive understanding, we have created an article covering the CD4047's Astable and Monostable Multivibrator modes, including detailed explanations of waveforms and simulation results. If you are interested in diving deeper into the various functionalities and practical applications of the CD4047, please check out the article. It offers valuable insights and detailed guidance, perfect for anyone looking to expand their knowledge or enhance their projects