Industrial Multi-Layer Power PCB

I am developing the True Ridge TRB-4CH-W, a modular industrial 12 VDC relay controller based on the ESP32-S3.

I am seeking an experienced electronics/electrical engineer to design and validate the COMPLETE ELECTRICAL SCHEMATIC.

This project is for SCHEMATIC DESIGN ONLY. PCB placement/routing, Gerber generation, enclosure design and production firmware are not part of this job.

The completed schematic package will be provided to JLCPCB or another PCB layout service for PCB layout and prototype manufacturing.

SYSTEM REQUIREMENTS

The TRB-4CH-W will use an ESP32-S3-WROOM-1U and provide:

- Nominal 12 VDC power input
- 4 independently controlled relay channels
- Maximum design target of 30 A at 12 VDC per relay output channel
- Field-replaceable power relays
- Individual field-replaceable fuse for each relay output
- 4 protected nominal 12 VDC digital inputs
- 2 protected 0-10 V analog inputs
- CAN/TWAI communications
- Electronically controlled 120-ohm CAN termination
- USB-C service/programming interface
- Support for up to 4 identical TRB-4CH-W modules on the CAN network, providing 4, 8, 12 or 16 relay channels

ELECTRICAL DESIGN REQUIREMENTS

The engineer will be responsible for designing and selecting the appropriate components for:

- ESP32-S3-WROOM-1U integration
- 12 VDC input power circuitry
- Voltage regulation for the ESP32-S3 and low-voltage electronics
- Reverse-polarity protection
- Input overcurrent protection
- Appropriate transient/surge protection
- Appropriate ESD protection
- Power filtering and decoupling
- 4 relay driver circuits
- Relay coil suppression
- 4 protected 12 VDC digital input circuits
- 2 protected 0-10 V analog input circuits
- Analog input scaling and filtering
- CAN/TWAI transceiver and protection
- Electronically controlled 120-ohm CAN termination
- USB-C service/programming circuitry
- ESP32 boot/reset and brownout-safe circuitry
- Appropriate diagnostic/test points or signals where required

HIGH-CURRENT REQUIREMENT

The four relay outputs have a maximum design target of 30 A at 12 VDC per channel.

This is an important engineering requirement.

The engineer must determine and document the appropriate electrical architecture for these high-current paths.

Do NOT assume that ordinary PCB traces will be sufficient for 30 A.

The schematic/design documentation must specify the recommended relay, fuse and high-current connection/conductor architecture and identify where heavy copper, bus bars, relay sockets, off-board heavy-current conductors or another appropriate method is required.

The engineer should consider continuous current capability, inrush loads, inductive loads, voltage drop, heating, protection and safe operating limits.

SAFE RELAY OPERATION

All relay outputs must remain OFF during initial power-up and ESP32 reset until intentionally enabled by firmware.

Uninitialized ESP32 GPIO pins must not unintentionally energize a relay.

Brownout, reset or unstable power conditions must not cause uncontrolled relay activation.

ESP32 GPIO MAP

A complete ESP32-S3 GPIO/interface map is required showing:

- Relay controls
- Digital inputs
- Analog inputs
- CAN/TWAI TX and RX
- CAN termination control
- USB/programming functions
- Status/diagnostic signals
- Any other required GPIO

The design must avoid ESP32-S3 boot-strapping or restricted-pin conflicts.

COMPONENT SELECTION

The engineer must select appropriate components and provide manufacturer names and manufacturer part numbers.

Components should preferably be readily available through major distributors and/or LCSC/JLCPCB where practical.

Please identify any critical or difficult-to-source components.

PCB footprint assignments must be provided for all components so the completed schematic can be handed directly to a PCB layout engineer.

DELIVERABLES

The completed project must include:

- Complete editable schematic source files
- Complete schematic in PDF format
- Complete BOM with manufacturer names and manufacturer part numbers
- ESP32-S3 GPIO/interface map
- PCB footprint assignments and required footprint library information
- Engineering notes/calculations supporting the power supply and protection circuits
- 0-10 V analog input scaling information
- CAN/TWAI interface information
- Engineering documentation for the 30 A relay/output architecture
- List of design assumptions, limitations and items requiring prototype validation

The final schematic package must be complete enough to hand directly to JLCPCB or another professional PCB layout engineer without requiring them to redesign the electrical circuit.

EDA SOFTWARE

EasyEDA Pro or KiCad is preferred because the PCB layout/prototype stage may be completed through JLCPCB.

Altium Designer is also acceptable if all editable source files and footprint information are supplied.

Please state which EDA software you will use.

PROJECT SCOPE

This job is for ELECTRICAL SCHEMATIC DESIGN ONLY.

PCB placement and routing, Gerber generation, enclosure design, external cable/harness design and production application firmware are NOT required as part of this project.

When submitting your bid, please provide:

- Fixed price for the complete schematic-design scope
- Estimated completion time
- EDA software you will use
- Number of revisions included
- Relevant ESP32-S3 experience
- Relevant CAN bus experience
- Relevant 12 V industrial electronics experience
- Relevant high-current relay/power design experience
- Examples of similar work if available

Please specifically confirm in your proposal that you are comfortable engineering and documenting the 30 A per-channel relay/output architecture.

I am looking for an engineer who will perform the required electrical engineering and component selection, not simply convert the requirements into a schematic drawing.