Digital Electronics Course - Lecture 1

Introduction

• The course is also known as:
  • Digital Logic
  • Digital Logic and Designing
• Content will be consistent across different colleges.

Overview of Signals

• A signal is a function representing the variation of a physical quantity with respect to an independent parameter (usually time or distance).
• Function:
  • Denoted as f(x)
  • Example: f(x) = -ax² + bx + c

Daily Life Example of Signal

• Example: Measuring temperature:
  • A boy measures temperature from 9 a.m. to 9 p.m. every minute.
  • Example Data:
    • 9:00 a.m. = 27°C
    • 9:01 a.m. = 27.5°C
• Plotting Temperature vs. Time:
  • X-axis: Independent quantity (time, t)
  • Y-axis: Dependent quantity (temperature, T)
  • Example graph shows a downward parabola if a > 0.

Understanding Functions

• Parameters:
  • If a = 0, the graph is a straight line (y = mx + c).
  • If a < 0, the graph is an upward parabola.
• Conclusion:
  • The function is the signal indicating how temperature changes over time.

Electrical and Electronics Signals

• In this context, signals represent variations in electrical quantities (usually current or voltage) with respect to time.
• Clarification:
  • If current or voltage does not change over time, it is not considered a signal (e.g., direct current).
• Graph for Direct Current:
  • Current I at different times T1 and T2 remains constant (I0).

Transducers

• Definition:
  • Device converting non-electrical signals to electrical signals (and vice versa).
• Example:
  • Microphone converts sound (non-electrical) to electrical signals.
  • Amplifier processes and amplifies the signal.
  • Speaker converts the amplified electrical signal back to sound.

Conclusion

• Various types of signals exist, and we've covered a basic example with temperature.
• Next lecture will cover analog signals, discrete-time signals, and digital signals.