Frequency Generator Tutorial

Introduction

• Presenter back for circuits tutorial
• Focus: Building a frequency generator

Types of Waves

• Square Wave
• Triangle Wave
• Sinusoidal Wave
• The circuit will generate all three types.

Circuit Overview

Key Components

• Two LM741 operational amplifiers
  • Pinout provided for reference
• Passive components: resistors, potentiometer, capacitor

Relaxation Oscillator

• Potentiometer controls capacitor charging rate
  • Charging time = half of output frequency
• Feedback loop created to enable self-oscillation

Power Supply

• Split power supply needed for AC wave
• Using two 9-volt batteries
• Added Zener diodes to limit voltage to 5 volts

Sanity Check

• Output checks:
  • Square wave from first op-amp
  • Triangle wave from second op-amp
• Frequency adjustments via potentiometer

Generating a Sine Wave

• Triangle wave fed into a wave shaper
• Wave shaper uses silicon diodes (0.7 volts drop) to convert triangle to sine wave

Amplification

• Added amplifier to boost sine wave voltage
• Configuration leads to an inverting amplifier setup

Final Steps

• Added push-pull amplifier for increased current handling
  • Uses PNP and NPN transistors
• Allows current output limited by transistors

Oscilloscope Verification

• Final output appears similar to op-amp output but can handle more current
• Clean output with potential distortion fix using small capacitor to ground

PCB Design

• PCB available for easier assembly
• Integrated wiring for simplified component placement
• Gerber files linked in description for manufacturing

Final Circuit Capabilities

• Default output: sine wave
• For triangle wave: omit wave shaper
• For square wave: add jumper wire from output to push-pull amplifier

Design Limitations

• Operational amplifiers: +15V to -15V ceiling voltage
• Frequency limit: 100,000 Hz before performance degrades

Conclusion

• Encouragement to build the circuit on breadboard or PCB
• Openness to community questions in comments
• Invitation to subscribe for more tutorials