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Created by Hans@gormed⌨Owner

Pump control

Some research already done (via CHatGPT):

Using a MOSFET to control a 12V pump with your Raspberry Pi Zero W is a great option, especially if you prefer a solid-state solution with potentially faster switching times and less power consumption compared to a relay. The wiring will be somewhat different from using a relay module. Here’s how you can wire it using an N-channel MOSFET, which is common for low-side switching:

Components Needed:

  1. N-channel MOSFET: Suitable for 12V and sufficient current rating for your pump.
  2. Gate Resistor: A small resistor (100Ω to 1kΩ) between the GPIO pin and the gate of the MOSFET to limit the gate current.
  3. Flyback Diode: A diode across the pump to protect the MOSFET from voltage spikes caused by the inductive load.
  4. Pull-down Resistor: About 10kΩ resistor between the gate and ground to ensure the MOSFET turns off when the GPIO pin is inactive.

Wiring Diagram

+12V DC Power Supply
│
├───┐
│    └─[Fuse]───[Pump]───[Drain of MOSFET]
│                          │
│                          └─[Source of MOSFET]───[Ground]
│
└─[DC-DC Converter (input)]
    │
    └─[DC-DC Converter (output 5V)]
         │
         ├───[Raspberry Pi Zero W]
         │       │
         │       └─[GPIO Pin]───[Gate Resistor]───[Gate of MOSFET]
         │                                    │
         │                                    └─[Pull-down Resistor]───[Ground]
         │
         └─[Ground]───────────────────────────[Ground connection]

Detailed Explanation:

  • Power Supply to Pump: Connect the positive terminal of your 12V power supply to one terminal of the pump.
  • Pump to MOSFET: Connect the other terminal of the pump to the drain terminal of the N-channel MOSFET.
  • MOSFET to Ground: Connect the source terminal of the MOSFET to the ground.
  • GPIO to MOSFET Gate: Connect a GPIO pin on the Raspberry Pi through a gate resistor to the gate of the MOSFET. This resistor protects the GPIO pin and controls the current flowing into the gate.
  • Pull-down Resistor: Connect a pull-down resistor from the gate to the ground. This ensures that the MOSFET remains off when the GPIO pin is not actively driving the gate.
  • Flyback Diode: Place a diode across the pump terminals, ensuring the cathode (marked end) is connected to the positive supply and the anode to the connection between the pump and the drain of the MOSFET. This diode protects the MOSFET from any back EMF generated by the pump when turned off.

Considerations:

  • MOSFET Selection: Ensure that the MOSFET can handle the maximum current your pump requires and that it fully turns on at the voltage level provided by the Raspberry Pi GPIO (3.3V). Look for a logic-level MOSFET for best performance.
  • Safety Checks: As always, double-check all connections with a multimeter before powering up the circuit. Be especially cautious of the orientation of the flyback diode.

Using a MOSFET allows for efficient and effective control of high-power devices such as your 12V pump, with minimal physical contact and wear, thanks to the absence of mechanical parts as found in relays.

Additional