12VDC SRD Relay PCB & Case

12VDC SRD Relay PCB & 3D Printed Case Project

This project is a compact and reliable 12VDC relay control module designed for general-purpose switching applications. It includes both the custom PCB design files and a matching 3D printable enclosure for secure installation and clean cable management.

The circuit is built around the widely available SRD-12VDC-SL-C relay and features an isolated trigger input using a PC817 opto-coupler with a 1kΩ input resistor, helping protect sensitive control electronics from electrical noise and voltage spikes.

Features

• Supports 12VDC operation

• Uses SRD-12VDC-SL-C relay

• 10A maximum switching capacity

  • 5A recommended for continuous and long-term reliability

• Opto-isolated trigger input using:

  • PC817 opto-coupler

  • 1kΩ current-limiting resistor

• Compact PCB layout

• Matching 3D printable protective case

• Designed using commonly available through-hole components

• Suitable for automation, hobby, automotive, and low-voltage control projects

Included Files

• PCB schematic files (PDF included)

• PCB layout / Gerber files (ZIP included)(Can be produced by JLCPCB, PCBWAY, ect...)

• Bill of Materials (PDF included)

• 3D printable enclosure files (STL)

• Assembly reference files (PDF included)

Circuit Board can be purchased at link below:

12VDC Relay Printed Circuit Board on Ebay

Applications

• Automotive/ATV/Motorcycle

• Arduino / micro-controller relay control

• Low-voltage automation systems

• Remote switching

• Lighting and accessory control

• DIY electronics projects

Important Notes

• Ensure proper wire sizing and terminal ratings for higher current loads.

• Continuous operation above 5A not recommended (10A Max short surge intervals only)

• Always observe safe isolation practices when switching mains or inductive loads.

This project is intended for educational, prototyping, and general low-voltage switching applications.