3: PCB layout for the automatic water dispenser Fig. A PCB layout for the automatic water dispenser is shown in Fig. You can either use a veroboard, or the designed PCB layout given here. But when there is an object/obstacle in front of TCRT5000, LED1 glows and, at the same time, the water pump is switched on and water flows out from the tap. Initially, when there is no object such as a hand or pet in front of TCRT5000, LED1 remains off and no water flows out as the water pump also remains off. 2: Circuit diagram of the automatic water dispenser It is built around tone decoder NE567 (IC1), optical reflective sensor TCRT5000L (OS1), two 1N4007 rectifier diodes (D1 and D2), two transistors S8050 and S8550 (T1 and T2), and a few other components. The circuit diagram of the automatic water dispenser is shown in Fig. Circuit and working of automatic water dispenser Nevertheless, the driver circuitry can be replaced with a low-current 5V relay because IC1 can merrily source current up to 100mA. So, the VBE of T2 becomes 0V (5.3–5.3=0) and keeps T2 and M1 dead off. Since the transistor switches the high voltage on and off (instead of ground), the setup provides a good return path when the water pump motor is turned off, and hence there’s not much undesired electromagnetic interference (EMI).įurther, when the output of IC1 goes high (idle state), the base resistor (R7) of T2 is floating. Here, S8550 pnp transistor (T2) is used as a high-side switch to drive the water pump motor (M1). Fortunately, we can prevent such a mishap by adding a mini float switch to the wiring of the water pump. Make sure that the water level is always higher than the motor as dry run will damage the water pump motor in a flash. (It is recommended to use a prime version water pump for a permanent fixture.) Just attach a small rubber/silicone hose to the motor outlet, and submerge it in water to run it. Water pump driverĪny 3-6V water pump motor should work with this little driver built around transistor T2. The next key component is the compact TCRT5000L reflective sensor, which includes a 950nm IR emitter and phototransistor in a leaded package that blocks visible light. ![]() The bandwidth centre frequency and output delay are independently set using just four external components. Its primary function is to drive a load whenever a sustained frequency within its detection band is present at the self-biased input. This tone and frequency decoder is a highly stable phase-locked loop (PLL) with synchronous AM lock detection and power output circuitry. To keep the complexity and cost within limits, a reliable IR proximity sensor has been developed with the help of a PLL tone decoder IC NE567. These sensors should be covered partially to prevent erroneous operation. You also have to properly mount the sensors so that these are not exposed to strong sunlight/ambient light. While industrial-grade sensors are extremely efficient, most readymade pre-wired sensor modules are prone to iterated false triggering, which badly affects the intended performance. The use of an IR proximity sensor is a practical way to build an automatic water dispenser. Also, there is a power supply block that holds a couple of standard dry cells. The system consists of three key segments: infrared (IR) proximity sensor, water pump driver, and mini submersible water pump. ![]() The presented system also offers many possibilities for extensions. It is a portable general-purpose automatic water dispenser perfectly suitable for homes to wash hands or feed water to pets. So, a relatively low-cost do-it-yourself solution is presented here. A branded automatic water dispenser is usually expensive.
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