Bin project

E-bin

E-bin is a modular bin where you can sort you wastes. You can connect until 5 bins together.
Each bin has a weigh device linked to a main board. After calibration, you can know each bin and global weights.

E-bin is made with 3mm MDF for the core bins, PLA for screws and weigh system.
Electronic device is based on ATtiny 44/84 with rotary encoder and LCD display

You can do it in a Fab Lab for less than 20$.

Bill of materials

• MDF 3mm 600x400mm 2,5sheets / bin
• PLA 46g / bin
• 4 springs / bin (I took pencil spring)
• 1 ATtiny 84
• 1 LCD Display 16x2 I2C
• 1 rotary encoder
• 1 uF capacitor
• 3 10k resistors
• 1 audio jack 3.5mm
• 1 5V alimentation
• 1 potentiometer / bin
• 1 3x2 pin connector
• 2 4 pin connector
• 5 3 pin connector
• 1 PCB

Problems and solutions

• I put slide bar on the outside box to maintain the inside bin vertical. At the begining, I just put a weigh system in the front side but it didn't work well because there were only springs in the front side.
  I add the same spring system but without gear and potentiometer in the back side and problem is fixed.
• Because of friction, box doesn't always go back to the same position so measures are less precise.
  I'll try to reduce friction, maybe with soft soap.
• I made my board with ATTiny44 because I didn't have ATTiny84 in the Lab but my firmware use 3958 bytes (96%) of program memory and I had to reduce number of bins to make use less than 90% of SRAM.
  I need to redo my board with an ATtiny84 if I want to add new functions or bins.

To evaluate my bin, I put different stuff I weigh before on a balance. After calibration, weigh is reproductible and error less than 5%.

Improvements

E-bin are really basic bins but can be really improved. Some wastes can be sort to be recycled but others (organic, paper...) should better be recycled locally in the bin.

• Add lids to bin for hygienic reasons
• Write calibration parameters and weights data in EEPROM to keep it
• Automatically detect when a bin is emptied and use it for computation
• Add a composter for organic wastes
• Add a way to recycle paper and cardboard