A Pulse Amplitude Modulation (PAM) circuit implementation using the versatile 555 timer IC and a transistor switch.
This project demonstrates a simple yet effective PAM circuit that modulates the amplitude of a carrier signal based on an input message signal. The 555 timer generates the carrier pulse train, while a transistor acts as an electronic switch to control the amplitude modulation.
The circuit consists of two main stages:
1. Pulse Generator (555 Timer)
- Configured in astable mode to generate a continuous square wave
- Acts as the sampling pulse/carrier signal
- Frequency can be adjusted using timing resistors and capacitor
2. Switching Stage (Transistor)
- Functions as an electronic switch controlled by the message signal
- Modulates the amplitude of the carrier pulses
- Output varies in amplitude proportional to the input signal
The 555 timer produces regular pulses at a fixed frequency. The message signal (analog input) is applied to the base of the transistor, controlling its conduction. When sampling pulses arrive, the transistor switches the message signal amplitude onto the output, creating PAM - discrete pulses whose heights represent the instantaneous amplitude of the message signal.
- 555 Timer IC
- NPN Transistor
- Resistors (values depend on your design)
- Capacitors (timing capacitor for 555)
- Power supply
- Analog-to-digital conversion basics
- Communication systems demonstrations
- Educational projects for understanding modulation techniques
- Signal processing experiments
This project is licensed under the MIT License - see the LICENSE file for details.
Ashish
Feel free to fork this project and submit pull requests for improvements!