DIY Electronic Project: Building a 16-Channel Analog Multiplexer Using the CD4067BM
In electronics, there are often situations where you need to manage multiple analog signals but have limited input or output pins available on your microcontroller or analog-to-digital converter (ADC). This is where an analog multiplexer comes in handy. In this DIY project, we'll build a 16-channel analog multiplexer using the CD4067BM, a versatile and widely-used CMOS component.
What is the CD4067BM?
The CD4067BM is a 16-channel analog multiplexer/demultiplexer that allows you to route one of 16 input signals to a single output line or vice versa. It operates by using digital control signals to select which of the 16 channels is connected to the common input/output. The CD4067BM is highly useful in applications requiring the monitoring or controlling of multiple signals with a single line, such as sensor arrays, data acquisition systems, and complex signal routing setups.
Components Required
To build this analog multiplexer, you’ll need the following components:
CD4067BM: The main component that provides 16 channels of analog multiplexing.
Microcontroller (e.g., Arduino): To control the selection of channels.
Resistors (10kΩ): For pull-down purposes, ensuring stable digital control signals.
Capacitors (100nF): For power supply decoupling, stabilizing the circuit.
Analog Sensors or Signal Sources: To be connected to the multiplexer inputs.
Breadboard or PCB: For assembling the circuit.
Wires and Connectors: For connections.
Power Supply: Typically 5V DC for the CD4067BM and the microcontroller.
Soldering Kit: For assembling the components on the board.
Circuit Design
Channel Selection: The CD4067BM uses four digital control lines (S0, S1, S2, S3) to select one of the 16 input channels. These control lines are connected to the digital output pins of a microcontroller, such as an Arduino. By setting these pins high or low, you can select which channel is routed to the common input/output.
Input/Output Configuration: The 16 inputs (labeled X0 to X15) can be connected to various analog signals or sensors. The common input/output pin (labeled as COM) is where the selected channel’s signal will appear. This pin can be connected to an ADC input on the microcontroller for signal reading.
Power Supply and Decoupling: The CD4067BM requires a stable 5V power supply. To ensure smooth operation, a 100nF capacitor is placed between the power supply pins (VDD and VSS) to filter out any noise.
Pull-down Resistors: 10kΩ resistors are connected to the digital control lines to ensure that they are pulled to a known state (low) when not actively driven by the microcontroller. This prevents any unintended channel selection due to floating inputs.

Assembly and Testing
Start by placing the CD4067BM on a breadboard or PCB. Connect the digital control lines to the microcontroller, and the common input/output pin to an ADC input or another analog input on the microcontroller. Attach your analog sensors or signal sources to the multiplexer’s inputs.
Once assembled, program the microcontroller to cycle through the 16 channels by adjusting the digital control lines. You can write a simple loop in Arduino to read the analog value from each selected channel and print it to the serial monitor.
Power up the circuit and observe the readings on your microcontroller. As the control lines change, the output should switch between the connected inputs, allowing you to monitor multiple analog signals using a single ADC input.
Applications
This 16-channel analog multiplexer is incredibly useful in projects where you need to monitor or manage multiple analog inputs with limited resources. It can be used in sensor arrays, audio mixing boards, or any project requiring efficient signal routing. The CD4067BM simplifies complex wiring and reduces the number of required ADC pins, making it an essential component in any electronics toolkit.
Conclusion
Building an analog multiplexer using the CD4067BM is a straightforward and educational project for electronics enthusiasts. It offers practical experience in managing multiple signals, using digital control, and efficiently utilizing microcontroller resources. Whether you're working on a data acquisition system, a complex sensor network, or just exploring the capabilities of CMOS components, this project provides a solid foundation for future analog and digital designs.
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