Quantity   Component name
1 × Arduino Uno (Board1)
1 × ultrasoic sensor HC-SR04 (US1)
1 × 5V single-changeover relay module (RM1)
1 × 12V DC motor (M1)
1 × Optocoupler IC(4N25)
1 × Switching transistor
1 × Status LED
1 × Freewheeling diode
1 × DC water pump