Object Counter For Conveyor

The Object Counter For Conveyor project operates by combining optical sensing, microcontroller logic, and multiplexed visual output to track items moving along a production line. Power enters the system via a 12V adaptor connected to a DC socket (J2). To protect the low-voltage logic components, an AMS1117-5.0 LDO voltage regulator (U5), supported by 10uF filtering capacitors (C1 and C2), steps down the 12V supply to a stable 5V rail for the Arduino Nano (U4). An infrared (IR) proximity sensor (U9), interfaced through a 3-pin connector (J1), acts as the primary detection element. Whenever an object passes on the conveyor belt, the IR sensor generates a digital pulse, which is read by the Arduino Nano. The microcontroller keeps a running tally of these detected pulses in its firmware. To display the count visually, the Arduino drives three common anode 7-segment displays (LTS 6960, U1-U3). Because driving multiple 7-segment digits requires managing segment lines and digit selection, the system employs MMBT5401 PNP transistors (Q1-Q3) acting as digit drivers, limited by 1KΩ resistors (R4-R6) on their base junctions. Additionally, three ULN2803A Darlington transistor array ICs (U6-U8) handle the higher current sinking requirements for the display segments, paired with 50Ω current-limiting resistors (R1-R3). The Arduino continuously cycles through the digits rapidly via multiplexing, allowing the three 7-segment displays to show the exact cumulative count of items passing the IR sensor in real time.