We use a DC motor and a 3D printed structure holding 4 magnets as our stirrer. The voltage to the circuit is controlled using PWM output values thus controlling the speed of the stirrer.

Materials Required

• DC - Geared Motor
• Neodymium magnets
• Transistor IRLIZ44N
• custom made 3D Structure

DC - Geared Motor

The DC Geared Motor we use is a combination of 4:4:1 gears and a brushed DC motor. The motor is cylindrical, with a diameter just under 25 mm, D shaped output shaft which is 4 mm in diameter and extends 12.5 mm from the face plate of the gear box. This motor unit weighing 95 gms, has a speed of 1400 RPM d and 150 mAmps Current rating at 6V.

Geared DC Motor

Magnets and 3D structure

Neodymium cubic supermagnets of size 5 mm are fitted into a 3D structure on the motor, to create a magnetic field for the fish inside the bioreactor. The 3D structure is a platform to be fitted on the DC motor, having cubical holes to fit the magnets in.

Transistor IRLIZ44N

It is a single pulse avalanche rated MOSFET in an isolated package. It has a continuous Drain current of maximum 30 Amps and Drain to Source maximum withstandable voltage of 16 volts.

Circuit

The circuit uses a Transistor and a Diode to control the RPM value using a PWM pin from Arduino.

Circuit Diagram for Stirrer Control

Assembly Video

Files

References