https://github.com/sanugiw/dual-mode-thermometer

The Dual-Mode Analog Thermometer is a precision temperature measurement device designed using analog components for high accuracy and reliability. Unlike fully digital thermometers, this design leverages thermistors, Wheatstone bridges, and an instrumentation amplifier to ensure precise readings.
https://github.com/sanugiw/dual-mode-thermometer

instrumentation-amplifier multi-mode oled-display thermistor-to-digital

Last synced: about 1 year ago
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The Dual-Mode Analog Thermometer is a precision temperature measurement device designed using analog components for high accuracy and reliability. Unlike fully digital thermometers, this design leverages thermistors, Wheatstone bridges, and an instrumentation amplifier to ensure precise readings.

• Host: GitHub
• URL: https://github.com/sanugiw/dual-mode-thermometer
• Owner: Sanugiw
• Created: 2025-01-11T16:23:25.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2025-04-23T13:32:25.000Z (about 1 year ago)
• Last Synced: 2025-04-23T13:58:33.703Z (about 1 year ago)
• Topics: instrumentation-amplifier, multi-mode, oled-display, thermistor-to-digital
• Homepage:
• Size: 44.5 MB
• Stars: 1
• Watchers: 1
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# 🏥 Dual-Mode Analog Thermometer  

![Project Banner](Images/image.png) 

## 📌 Overview  

The **Dual-Mode Analog Thermometer** is a precision temperature measurement device designed using **analog components** to ensure high accuracy and reliability. Unlike fully digital thermometers, this design utilizes **thermistors, Wheatstone bridges, and an instrumentation amplifier** for precise temperature readings.  

This project was developed as part of the **EN2091 Laboratory Practice and Projects** module in our 3rd semester, focusing on **hands-on circuit design, sensor integration, and analog signal processing**.  

## ⚡ Features  

✅ **Dual-Mode Functionality** – Toggle switch to switch between **body temperature** and **liquid temperature** modes.  

✅ **High Accuracy** – Uses **thermistors, Wheatstone bridges, and an instrumentation amplifier** for precise readings.  

✅ **OLED Display** – Temperature readings are displayed on an **OLED screen**, with an **Arduino** used solely for display purposes.  

✅ **Stable Power Supply** – Converts **AC to +10V, -10V, and 5V** for reliable operation.  

✅ **Future Expansion** – Plans to integrate a **MUX** for additional modes.  

## 🛠️ Development Tools  

- **Circuit Simulation**: 🖥️ LTspice  

- **Schematic & PCB Design**: 🖊️ Altium Designer  

- **Enclosure Modeling**: 📐 SolidWorks  

## 📷 Hardware Overview  

| Component           | Function |

|--------------------|--------------------------------|

| **Thermistors** (NTC/PTC)  | Temperature sensing  |

| **Wheatstone Bridge**  | Signal conditioning |

| **Instrumentation Amplifier** | Precise signal amplification |

| **OLED Display** | Displays temperature readings |

| **Arduino** | Handles display functionality |

| **Power Supply** | Converts AC to +10V, -10V, and 5V |

## 🧩 Schematic & PCB Design

We designed both the **schematic** and **printed circuit boards (PCBs)** using **Altium Designer**. The project includes:

- 🧠 **Main Thermometer PCB** – Houses the signal conditioning circuit using Wheatstone bridges, thermistors, and an instrumentation amplifier.

- 🔋 **Dual Power Supply PCB** – Converts AC input into stable **+10V, -10V, and 5V** DC outputs. 

### 🖼️ Visuals:

![📐 Schematic](Images/schematic.jpeg)

> *Complete circuit schematic designed in Altium Designer.*

![🔧 Sensor PCB](Images/pcb_main.jpeg)

> *Main PCB for the analog thermometer circuit.*

![⚡ Power PCB](Images/pcb.jpeg)

> *Power supply PCB providing +10V, -10V, and 5V rails.*

---

## 🧱 Enclosure Design

To protect and house the electronics, we created a **cost-effective 3D-printed enclosure** using **SolidWorks**. The design features:

- 💡 **Compact & Ergonomic** layout for portability and ease of use.

- 🛠️ **Snap-fit joints** for quick assembly without screws.

- 🔄 **Modular access** to switch between body and liquid temperature modes.

- 📏 **Display window** for OLED visibility and button access.

### 🖼️ Visual:

![🧊 Enclosure](Images/enclosure.jpeg)

> *3D-modeled enclosure designed for compactness and cost-efficient 3D printing.*

## 🚀 Getting Started  

### 🔧 Requirements  

- **Components**: Thermistors, Wheatstone bridge circuit, instrumentation amplifier, Arduino, OLED display  

- **Software**: LTspice, Altium Designer, SolidWorks, Arduino IDE  

### 🏗️ Setup Instructions  

1. **Assemble the Circuit** using the schematic provided.  

2. **Program the Arduino** with the provided firmware.  

3. **Power the System** using a **+10V, -10V, and 5V power supply**.  

4. **Use the Toggle Switch** to switch between temperature modes.  

5. **Observe the Temperature Readings** on the OLED display.  

## 🤝 Contributors  

- Luchitha Perera

- Benul Wijayarathna

- Sanugi Wickramasinghe

- Hansani Kaumadi