Automatic Water Dispenser

The Automatic Water Dispenser project operates as a touchless fluid distribution system using a combination of optical sensing, tone decoding, and discrete semiconductor switching. At the heart of the detection system is the TCRT5000L reflective sensor, which emits infrared light and detects its reflection when an object, such as a hand or a cup, is placed near the dispensing nozzle. This optical detection triggers the control logic centered around the NE567 tone decoder IC, which processes the sensor state to determine when activation is required. To drive the high current needed by the mini submersible water pump (operating on 3-6V from standard dry cell batteries), the circuit uses a complementary transistor pair consisting of an S8050 NPN transistor and an S8550 PNP transistor. These transistors act as electronic switches, amplifying the control signal from the logic stage to safely power the pump motor without overloading the sensitive ICs. Meanwhile, 1N4007 rectifier diodes (D1 and D2) are integrated into the circuit to protect the components from voltage spikes and back-EMF generated by the inductive motor windings when the pump switches off. Once triggered, the submersible pump draws water and pushes it through a connected rubber or silicone hose, delivering a seamless, touchless flow of water.