Home Consumer Electronics Automated Water Dispenser | Full DIY Electronics Challenge

Automated Water Dispenser | Full DIY Electronics Challenge

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A branded automated water dispenser is normally costly. So, a comparatively low-cost do-it-yourself resolution is offered right here. It’s a transportable general-purpose automated water dispenser completely appropriate for properties to clean fingers or feed water to pets. The offered system additionally gives many prospects for extensions.

Block diagram for system overview
Fig. 1: Block diagram for system overview

The system consists of three key segments: infrared (IR) proximity sensor, water pump driver, and mini submersible water pump. Additionally, there’s a energy provide block that holds a few commonplace dry cells.

IR proximity sensor design

Using an IR proximity sensor is a sensible method to construct an automated water dispenser. Whereas industrial-grade sensors are extraordinarily environment friendly, most readymade pre-wired sensor modules are liable to iterated false triggering, which badly impacts the supposed efficiency. You additionally need to correctly mount the sensors in order that these should not uncovered to robust daylight/ambient mild. These sensors needs to be coated partially to stop faulty operation.

To maintain the complexity and value inside limits, a dependable IR proximity sensor has been developed with the assistance of a PLL tone decoder IC NE567.

This tone and frequency decoder is a extremely steady phase-locked loop (PLL) with synchronous AM lock detection and energy output circuitry. Its main operate is to drive a load at any time when a sustained frequency inside its detection band is current on the self-biased enter. The bandwidth centre frequency and output delay are independently set utilizing simply 4 exterior parts.

The subsequent key part is the compact TCRT5000L reflective sensor, which features a 950nm IR emitter and phototransistor in a leaded bundle that blocks seen mild.

Water pump driver

Any 3-6V water pump motor ought to work with this little driver constructed round transistor T2. (It’s endorsed to make use of a first-rate model water pump for a everlasting fixture.) Simply connect a small rubber/silicone hose to the motor outlet, and submerge it in water to run it. Ensure that the water degree is all the time greater than the motor as dry run will injury the water pump motor in a flash. Thankfully, we are able to forestall such a mishap by including a mini float swap to the wiring of the water pump.

Right here, S8550 pnp transistor (T2) is used as a high-side swap to drive the water pump motor (M1). For the reason that transistor switches the excessive voltage on and off (as an alternative of floor), the setup supplies a very good return path when the water pump motor is turned off, and therefore there’s not a lot undesired electromagnetic interference (EMI).

Additional, when the output of IC1 goes excessive (idle state), the bottom resistor (R7) of T2 is floating. So, the VBE of T2 turns into 0V (5.3–5.3=0) and retains T2 and M1 useless off.
Nonetheless, the driving force circuitry may be changed with a low-current 5V relay as a result of IC1 can merrily supply present as much as 100mA.

Circuit and dealing of automated water dispenser

The circuit diagram of the automated water dispenser is proven in Fig. 2. It’s constructed round 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 some different parts.

Circuit diagram of the automatic water dispenser
Fig. 2: Circuit diagram of the automated water dispenser

The working of the circuit is straightforward. Initially, when there isn’t any object equivalent to a hand or pet in entrance of TCRT5000, LED1 stays off and no water flows out because the water pump additionally stays off. However when there may be an object/impediment in entrance of TCRT5000, LED1 glows and, on the similar time, the water pump is switched on and water flows out from the faucet.

Development and testing

Wiring up the circuit is straightforward. You may both use a veroboard, or the designed PCB format given right here. A PCB format for the automated water dispenser is proven in Fig. 3 and its parts format in Fig. 4.

PCB layout for the automatic water dispenser
Fig. 3: PCB format for the automated water dispenser
Components layout of the PCB
Fig. 4: Parts format of the PCB

Obtain PCB and Element Format PDFs: click here

After assembling the circuit on the PCB, enclose it in a water resistant (clear/translucent) prototype enclosure. A standing indicator (LED1) has been added within the circuit, which glows when the proximity sensor detects an object/impediment. Repair the TCRT5000L sensor and LED1 on the entrance panel of the cupboard.

A trimpot (VR1) is used to set the working frequency of the oscillator. The ability provide used right here is 6V (4 AA/AAA cells) DC provide. It additionally powers the mini submersible water pump (M1). The ultimate proposed association is proven in Fig. 5. For troubleshooting, examine voltages at varied take a look at factors as per the desk.

Proposed arrangement of the automatic water dispenser
Fig. 5: Proposed association of the automated water dispenser

Observe. The system hardly wants any essential electrical changes. The working frequency of NE567 (IC1) may be tuned in 1kHz to 2kHz vary utilizing a 10-kilo-ohm potmeter (VR1). You may examine frequency at take a look at level TP1.

In case of legitimate proximity detection, take a look at level TP2 provides a worth higher than 150mV. The working distance lies in 7cm to 15cm vary relying upon the setting of the second 10-kilo-ohm trimpot (VR2).

Author’s prototype of pump driver
Fig. 6: Creator’s prototype of pump driver

The first output pin 8 of NE567 is definitely a free-floating output transistor collector. It provides a logic-low degree output (TP3) with 100mA current-sinking functionality on proximity detection.


T.Ok. Hareendran is an electronics designer, {hardware} beta tester, technical writer, and product reviewer

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