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.
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.
Assembly Video
Files
The files for the 3D structure can be found here : File:Aachen Stirrer3D.zip
The files for the Debug program can eb found here : File:Aachen StirrerDebug.zip
References