FunctionGeneratorPCB

Function Generator Using TL072 Op-Amp

An Analog Function Generator Designed Around the TL072 Dual Op-Amp

Overview

This project is a discrete analog function generator built using TL072 operational amplifiers.

The circuit generates multiple periodic waveforms through a combination of op-amp based waveform-generation and signal-conditioning stages. The project was developed from individual circuit stages, simulated in LTSpice, prototyped on a breadboard, and finally designed as a PCB using KiCad.

The project includes the complete design workflow:

Circuit Design → Simulation → Breadboard Prototype → KiCad Schematic → PCB Layout → 3D PCB

Features

• Analog function generator based on TL072 dual op-amp
• Square-wave generation
• Triangle-wave generation
• Sine-wave generation
• Adjustable signal gain/output stage
• LTSpice simulation
• Breadboard prototype implementations
• Complete KiCad schematic
• PCB layout
• 3D PCB visualization
• Frequency response/trend analysis
• Design documentation and circuit diagrams

Waveforms

The generator is designed around a waveform-generation chain in which the different stages produce and process the required signals.

Square Wave

The square-wave stage forms the primary waveform-generation section.

Triangle Wave

The triangle-wave stage converts the generated waveform into a triangular waveform.

Sine Wave

The sine-wave stage processes the generated waveform to obtain a sinusoidal output.

Functional Block Diagram

The overall design can be understood as a sequence of functional blocks:

                 ┌─────────────────────┐
                 │   Wave Generation   │
                 │      Stage          │
                 └──────────┬──────────┘
                            │
                            ▼
                 ┌─────────────────────┐
                 │  Waveform Shaping   │
                 │   / Conversion      │
                 └──────────┬──────────┘
                            │
              ┌─────────────┼─────────────┐
              │             │             │
              ▼             ▼             ▼
           Square        Triangle        Sine
              │             │             │
              └─────────────┼─────────────┘
                            │
                            ▼
                 ┌─────────────────────┐
                 │   Gain / Output     │
                 │       Stage         │
                 └──────────┬──────────┘
                            │
                            ▼
                         OUTPUT

Gain & Output Stage

A dedicated gain/output circuit is included to condition the generated waveform before it is presented at the output.

Simulation

The circuit was simulated using LTSpice before hardware implementation.

LTSpice Schematic

Simulation Results

Simulation was used to verify the circuit behavior and waveform generation before moving to physical implementation.

Hardware Prototype

After simulation, the individual stages were implemented and tested on a breadboard.

Square Wave Prototype

Triangle Wave Prototype

Sine Wave Prototype

The breadboard implementations were used to validate the practical behavior of the analog circuits before committing to the PCB design.

KiCad Design

The final hardware design was developed using KiCad.

Source Schematic

Core Circuit

Gain & Output

PCB Design

The complete PCB layout was created from the KiCad schematic.

3D PCB View

Prototype PCB Implementation

A zero-PCB implementation was also documented as part of the hardware development process.

Frequency Analysis

The project also includes analysis of how the oscillator frequency changes with component values.

Frequency vs Resistance

Frequency vs Capacitance

These plots provide a practical reference for understanding the relationship between the timing components and generated frequency.

Repository Structure

Function-Generator-using-TL072-OPAmp/
│
├── 3D Models/
│
├── Docs/
│   ├── 00 - Block Diagram.png
│   ├── 01 - Square Wave Circuit.png
│   ├── 02 Triangle Wave Circuit.png
│   ├── 03 - Sine Wave Circuit.png
│   ├── 04 - Gain Circuit.png
│   ├── 05 - LTSpice Schematic.png
│   ├── 06 - LTSpice Simulation Graph.png
│   │
│   ├── 10 - Breadboard Implementation Square.jpeg
│   ├── 11 - Breadboard Implementation Triangle.jpeg
│   ├── 12 - Breadboard Implementation Sine.jpeg
│   │
│   ├── 20 - KiCad Schematic - Source.png
│   ├── 21 - KiCad Schematic - Core Circuit.png
│   ├── 22 - KiCad Schematic - Gain & Output.png
│   ├── 23 - KiCad PCB Layout.png
│   ├── 24 - KiCad 3D View 1.png
│   ├── 25 - KiCad 3D View 2.png
│   │

Design Workflow

The project followed a complete electronics development workflow:

1. Circuit Design

Individual analog stages were designed for waveform generation and signal conditioning.

2. Simulation

The circuits were tested in LTSpice to verify their expected behavior.

3. Breadboard Prototype

The circuits were physically implemented on a breadboard and tested.

4. Schematic Capture

The validated design was recreated in KiCad.

5. PCB Layout

The complete circuit was converted into a PCB layout.

6. 3D Verification

The PCB was inspected using KiCad's 3D viewer to verify component placement and overall board design.

Design Files

The repository contains the main KiCad project files:

Tools Used

• KiCad — Schematic capture, PCB design and 3D visualization
• LTSpice — Circuit simulation
• TL072 Op-Amp — Core analog building block
• Breadboard — Hardware prototyping and validation

Learning Objectives

This project demonstrates several practical analog electronics concepts:

• Operational amplifier circuits
• Analog waveform generation
• Waveform conversion and shaping
• Signal amplification
• Frequency control
• Component-value analysis
• LTSpice simulation
• Breadboard prototyping
• Schematic capture
• PCB layout
• Hardware design verification

Project Documentation

All supporting diagrams, simulation results, prototype photographs, PCB designs and frequency-analysis plots are available in the Docs directory.

Status

Completed — Design, Simulation, Prototyping and PCB Development

The repository contains the design artifacts required to understand and reproduce the project, including the circuit schematics, PCB files, supporting documentation and prototype images.

Author

Rup Roshan Jha

Electronics / Hardware Design Project

License

See the repository for licensing information.