Propane Generator Controller


make me a PCB that has a three stage startup sequence using 3 electromechanical relays. This sequence is used to start a propane generator so it has a gas-on, prime and starter process. We also need adjustable temperature controller for a 12v fan system. AC input detection (up 120v+).
No PCB changes were made in this session because AI execution is unavailable due to insufficient ACUs. The current project remains the USB‑C Wi‑Fi/BLE temperature/humidity sensor design; preliminary parts previously identified include the SiWG917 module and SHT41 sensor.
For the new propane-generator controller, the remaining work is to define and implement:
  • Three adjustable relay stages: gas-on, prime, and starter
  • Safe timing, interlocks, retry limits, emergency shutdown, and fail-safe relay states
  • Adjustable 12 V fan-temperature controller
  • Galvanically isolated 120 VAC presence detection
  • 12 V input protection, transient suppression, relay-driver flyback protection, and appropriately rated connectors/clearances
  • Schematic verification, PCB layout, and manufacturing checks
Before design starts, the generator’s relay/solenoid coil voltages and currents, exact startup timing, available supply, fan current, temperature range, and whether 120 VAC is detection-only must be confirmed. Because this controls propane and mains voltage, final hardware should also undergo qualified electrical and combustion-safety review.
Define relay specs
Specify fan control
Clarify AC sensing
Add safety features
Start schematic capture

U2
D1
J1
U1
R1
Resistance
5.1kΩ
R13
Resistance
100kΩ
R4
Resistance
400kΩ
R7
Resistance
100kΩ
R10
Resistance
10kΩ
R3
Resistance
909Ω
R14
Resistance
100Ω
R2
Resistance
5.1kΩ
R8
Resistance
100kΩ
R9
Resistance
10kΩ
R6
Resistance
100kΩ
R11
Resistance
1kΩ
R12
Resistance
10kΩ
R5
Resistance
261kΩ
C4
Capacitance
10µF
C17
Capacitance
1nF
C7
Capacitance
100nF
C3
Capacitance
10µF
C5
Capacitance
10µF
C13
Capacitance
100nF
C2
Capacitance
10nF
C15
Capacitance
100nF
C8
Capacitance
1µF
C14
Capacitance
1µF
C9
Capacitance
10µF
C10
Capacitance
100nF
C1
Capacitance
1µF
C16
Capacitance
10nF
C6
Capacitance
10µF
C12
Capacitance
100nF
C11
Capacitance
100nF
U3
D2
U4
D4
D3
L1
SW1
SW2
LED1
J2

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