Pumps & valves
Everything here is an inductive load your GPIO can't drive directly. Pick the fluid or motion job first — valve, pump, push-pull plunger, linear push rod, lock or electromagnet — then size the MOSFET.
Solenoid valves (DN15/DN20 12V), 6V pneumatic air valves, push-pull and lock-style solenoids, 5V electromagnets (3–35kg holding force), 6V electric push rods (10–100mm stroke), peristaltic dosing pumps and submersible water pumps.
- The 12V DN15 and DN20 solenoid valves are normally closed until powered and meant for liquids; the 6V air valves (2-position 3-way) are for pneumatics, not water.
- Peristaltic pumps — Gravity's Digital Peristaltic Pump and Adafruit's 5–6V and 12V tubing pumps — meter liquid without it touching the motor; the submersible 3V/6V pumps move volume but can't dose.
- 5V electromagnets span 3kg to 35kg holding force at 1–3W; holding force is not lifting capacity — the 25kg unit realistically picks up about 3kg. 6V electric push rods (10–100mm stroke, 128N) are the linear-actuator branch.
- Lock-style solenoids (6V and 12V with JST leads) and the 9–12V Electric Solenoid Lock are momentary-duty: drive them through a transistor with a flyback diode, never continuously.
