Hardware - GlasgowTeam3RTEP/Excellentea GitHub Wiki

The hardware required for this project include electronic components for circuit implementation and the components used to build the body of the tea maker. The main components required are listed below:

Circuit components

• Raspberry PI microcontroller board (tested on version 3 Model B)
• Reed float sensor (59630)
• Digital temperature sensor (ds18b20)
• Heating element (12V) (B004O8BGXE)
• Unipolar Stepper motor (MIKROE-1530)
• 16x2 LCD (HD44780U controller)
• I2C lcd backpack (MCP23008 expander)
• Tea infuser
• Darlington transistor array (ULN2803A)
• N-channel logic-level MOSFET (FQP30N06L)
• MOSFET heat sink (507222B00000G)
• 4k7 Resistor
• 10k Resistor
• 12V DC power supply

The circuit schematic is given below. The 16x2 display is connected to the raspberry pi through an I2C backpack. The latter is powered by the 5V on-board output and communicates via the serial data (SDA) and serial clock (SCL) pins on the raspberry pi. The One-wire bus is pulled-up to 5V via a 4.7KOhms resistor and is connected to pin 7 on the pi. The float sensor, being a mere switch, is connected to the board through a 10KOhm pull-up resistor. The 12V heating element is switched on and off with a logic-level MOSFET and finally, the stepper motor is controlled with a Darlington transistor array.

A custom PCB can be printed from the files found here according to the schematic above.

Body components:

• 2 side panels
• 1 back panel
• 2 front panels (one of which includes a cut for the LCD)
• 2 motor support blocks
• 4 cover panels used for top and bottom (one includes a cut for the tea strainer)
• 1 motor shaft (3D printed)

All parts were designed in Solidworks. Unless otherwise stated they were laser cut and made of 3 mm sheet acrylic. The 3D printed component is made of PLA.

Engineering drawing of 3D printed part:

Engineering drawing of laser-cut parts: