Standby Generator PCB Design
Budget: $250 – $750 USD
I'm looking for an experienced PCB designer to create a control board for my standby generator. The PCB should manage an Automatic Transfer Switch (ATS) and engine control, and should include:
SPARXX ATS REV A – PCB DESIGN SPECIFICATION
Project
Design a production-ready PCB-based Automatic Transfer Switch (ATS) controller to replace an existing relay/timer panel while maintaining the same operating logic.
Deliverables Required
Complete KiCad 9 project
Schematics
PCB Layout
BOM
Gerber files
Pick and Place files
Programming header
Source files
PCB Size
Approximately
3.5" × 7" × 0.5" maximum
Reserve approximately 20% of board space for future expansion.
Power
Inputs:
120 VAC
12 VDC Generator Supply
Board must automatically power from either source.
No batteries.
Use supercapacitor hold-up circuit to maintain MCU operation during transfer (approximately 2 minutes).
Use encapsulated 120VAC → 12VDC AC/DC module.
Generate regulated 5V for MCU.
Controller
Microcontroller:
ATmega328P (internal oscillator, no external crystal)
Include:
ISP programming header
Watchdog timer
Event memory (software only if possible)
Relay Outputs
K101
Generator Start
Requirements:
Dry contact only
Generator provides its own 12VDC
Board simply closes contacts
K102
Transfer Contactor
120VAC
Coil current under 1 amp
Relay rated minimum 10A
Inputs
Utility Sense
Generator Sense
S1 Three Position Switch
Up = Auto Transfer
Center = Off
Down = Auto Solar Transfer
S2 Three Position Switch
Up = Auto Generator
Center = Off
Down = Manual Generator
Manual Generator Mode
Generator starts immediately.
Transfer occurs whenever generator voltage is present.
Works regardless of S1 position except when safety logic prevents transfer.
Automatic Generator Mode
Utility failure
↓
Adjustable startup delay
↓
Generator starts
↓
Adjustable warm-up delay
↓
Transfer
↓
Utility returns
↓
Immediate transfer back
↓
Adjustable cooldown
↓
Generator stop
Cooldown selectable using 4-position DIP switch.
Solar Automatic
Battery inverter acts as generator.
No generator start command.
If generator input voltage exists:
Transfer.
No warm-up delay required.
Service Mode
S1 Center disables automatic transfer.
Automatic generator start disabled.
Manual generator operation remains available.
Adjustable Timing
Two potentiometers
RV1
Generator start delay
RV2
Warm-up / return timing
Cooldown selected by DIP switch.
Indicators
LED
Power
LED
Utility
LED
Generator
LED
Transfer
Optional MCU heartbeat LED.
Protection
Fuse
MOV
Proper AC isolation
Creepage clearance
Connectors
Clearly labeled screw terminals.
Industrial field wiring.
Silkscreen labels.
PCB Requirements
Single PCB.
Through-hole components preferred where practical.
Cost optimized.
Easy assembly.
Easy servicing.
Professional silkscreen.
Firmware
Implement state machine according to supplied operating description.
Goal
Replace an existing relay-based ATS with a microcontroller-based controller having identical behavior while reducing wiring complexity and assembly time.
I would also include this note at the bottom:
The operating logic is already defined. The objective is not to redesign the ATS, but to implement the existing logic in a production-ready PCB. Questions about ambiguous behavior should be resolved with the client before changing functionality.
SPARXX ATS REV A – PCB DESIGN SPECIFICATION
Project
Design a production-ready PCB-based Automatic Transfer Switch (ATS) controller to replace an existing relay/timer panel while maintaining the same operating logic.
Deliverables Required
Complete KiCad 9 project
Schematics
PCB Layout
BOM
Gerber files
Pick and Place files
Programming header
Source files
PCB Size
Approximately
3.5" × 7" × 0.5" maximum
Reserve approximately 20% of board space for future expansion.
Power
Inputs:
120 VAC
12 VDC Generator Supply
Board must automatically power from either source.
No batteries.
Use supercapacitor hold-up circuit to maintain MCU operation during transfer (approximately 2 minutes).
Use encapsulated 120VAC → 12VDC AC/DC module.
Generate regulated 5V for MCU.
Controller
Microcontroller:
ATmega328P (internal oscillator, no external crystal)
Include:
ISP programming header
Watchdog timer
Event memory (software only if possible)
Relay Outputs
K101
Generator Start
Requirements:
Dry contact only
Generator provides its own 12VDC
Board simply closes contacts
K102
Transfer Contactor
120VAC
Coil current under 1 amp
Relay rated minimum 10A
Inputs
Utility Sense
Generator Sense
S1 Three Position Switch
Up = Auto Transfer
Center = Off
Down = Auto Solar Transfer
S2 Three Position Switch
Up = Auto Generator
Center = Off
Down = Manual Generator
Manual Generator Mode
Generator starts immediately.
Transfer occurs whenever generator voltage is present.
Works regardless of S1 position except when safety logic prevents transfer.
Automatic Generator Mode
Utility failure
↓
Adjustable startup delay
↓
Generator starts
↓
Adjustable warm-up delay
↓
Transfer
↓
Utility returns
↓
Immediate transfer back
↓
Adjustable cooldown
↓
Generator stop
Cooldown selectable using 4-position DIP switch.
Solar Automatic
Battery inverter acts as generator.
No generator start command.
If generator input voltage exists:
Transfer.
No warm-up delay required.
Service Mode
S1 Center disables automatic transfer.
Automatic generator start disabled.
Manual generator operation remains available.
Adjustable Timing
Two potentiometers
RV1
Generator start delay
RV2
Warm-up / return timing
Cooldown selected by DIP switch.
Indicators
LED
Power
LED
Utility
LED
Generator
LED
Transfer
Optional MCU heartbeat LED.
Protection
Fuse
MOV
Proper AC isolation
Creepage clearance
Connectors
Clearly labeled screw terminals.
Industrial field wiring.
Silkscreen labels.
PCB Requirements
Single PCB.
Through-hole components preferred where practical.
Cost optimized.
Easy assembly.
Easy servicing.
Professional silkscreen.
Firmware
Implement state machine according to supplied operating description.
Goal
Replace an existing relay-based ATS with a microcontroller-based controller having identical behavior while reducing wiring complexity and assembly time.
I would also include this note at the bottom:
The operating logic is already defined. The objective is not to redesign the ATS, but to implement the existing logic in a production-ready PCB. Questions about ambiguous behavior should be resolved with the client before changing functionality.