OBJECT COUNTER For Conveyor

Loading cement sacks into trucks requires precise counting for traceability, yet manual methods are error-prone and often lead to shipment discrepancies.

- A. SAMIUDDHIN

This system automates counting at the conveyor loading end, ensuring reliable per-truck tracking.

An infrared (IR) proximity sensor with a 3cm to 80cm range interfaces with an Arduino for processing and drives a display that counts objects on the conveyor. The components are listed in the Bill of Materials table.

Circuit and working

The circuit is built around three common-anode seven-segment displays (U1-U3), an Arduino Nano (U4), an AMS1117-5.0 LDO regulator (U5), three ULN2803A driver ICs (U6-U8), and an IR proximity sensor (U9) connected via a 3-pin header (J1). A 12V adaptor connected through DC socket J2 powers the circuit.

The Arduino Nano controls the counting process and displays the total on the 7-segment modules.

The power supply uses an AMS1117-5.0 low-dropout regulator to step down the 12V DC input to a regulated 5V. Capacitors C1 and C2 stabilise the supply and suppress voltage fluctuations. This 5V rail powers the Arduino Nano, the ULN2803A driver ICs, the displays, and the proximity sensor. Fig. 3 shows the circuit diagram of the system.

The Arduino generates segment control signals (a to g and the decimal point) along with digit-enable signals for multiplexing. The proximity sensor output connects to digital pin D2, allowing the controller to detect changes and update the display accordingly.

Each 7-segment display is driven through a ULN2803A Darlington transistor array, which reduces the current load on the Arduino I/O pins and ensures reliable driving of the display segments. The common pin of each ULN2803A is connected to the 5V supply to make use of the internal clamp diodes.