Digital Thermocouple Temperature Controller

A PIC-based temperature-control PCB designed in Altium for reading a K-type thermocouple, presenting the measured value on a 16x2 LCD, and switching an external load through a relay output stage.

System Architecture

The design combines:

• PIC16F877A-I/PT 44-pin microcontroller
• AD849x K-type thermocouple amplifier with cold-junction compensation
• RC1602B-BIW-CSV 16x2 blue-backlit LCD
• 5 V SPDT relay output
• NPN transistor relay driver with flyback diode
• Rotary potentiometer and push-button user controls
• External sensor/input and switched-load connectors
• Local filtering, decoupling, reset, and interface components

The thermocouple signal is conditioned by the AD849x front end and sampled by the microcontroller. The interface supports local display and setpoint control, while the relay stage provides switching contacts for an external control circuit.

Visuals

PCB assembly view	Altium schematic

A lightweight schematic preview is available at assets/schematic.png.

Repository Structure

.
|-- altium/
|   |-- digital-temperature-controller.PrjPcb
|   |-- digital-temperature-controller.PcbDoc
|   |-- digital-temperature-controller.SchDoc
|   |-- digital-temperature-controller.PrjPcbStructure
|   `-- Constraints.xml
|-- assets/
|   |-- altium-schematic.jpg
|   |-- pcb-front.jpg
|   |-- pcb-perspective.jpg
|   `-- schematic.png
|-- CONTRIBUTING.md
|-- LICENSE
`-- README.md

Opening the Project

1. Clone or download the repository.
2. Open altium/digital-temperature-controller.PrjPcb in Altium Designer.
3. Relink the LCD and connector libraries if the historical relative paths do not resolve.
4. Compile the project and run fresh schematic and PCB design-rule checks.

Design Status

This is a hardware design archive rather than a production-ready controller. The supplied folder did not include firmware, calibration records, a current DRC export, or fabrication outputs. Before practical use:

• verify the thermocouple polarity, gain, offset, and temperature range;
• define safe relay behavior for sensor, firmware, and power failures;
• confirm relay contact ratings and isolation for the intended load;
• add independent over-temperature protection where hazardous heating is possible;
• generate and review manufacturing files from a clean DRC result.

Scope and Limitations

• No microcontroller firmware is included.
• No temperature-control algorithm or calibration dataset is included.
• No Gerber, drill, bill-of-materials, or assembly package is included.
• The design is not safety-certified and must not be treated as a standalone protective device.

License

Copyright (c) 2026 ennap3a. All rights reserved. See LICENSE.