Do-it-yourself water leakage protection for the home. Water sensor circuit Do-it-yourself water leak control

Hello 🙂

Slowly but surely, we approached concluding article dedicated to .

In this article, we will look at the process creating a water detection sensor from improvised materials.

In the previously discussed automatic pump shutdown system, the principle of electrical conductivity of the aquatic environment. Water is a very good conductor of electricity. Therefore, in order to manufacture a water detection sensor, we it is necessary to ensure contact between the outputs of the logic module and the suspected location of the water leak.

Making a water detection sensor

To make a sensor, we need:

• Bolts M4 - 2 pcs
• Nuts M4 - 2 pcs
• Washers M4 - 4 pcs
• Two-core copper wire - 3 meters
• Lid from drinking water(larger diameter) - 1 pc.
• Cover from kefir or milk (smaller diameter) - 1 pc.
• Hot melt adhesive (or sealant)

The dimensions of the lids are selected so that one of them can be easily inserted into the other, thus forming a closed water sensor housing. If necessary, you can remove factory inscriptions and logos from the covers with acetone.

We drill holes with a diameter of 3.5 mm in the covers at the same distance from the center of each cover. I draw your attention to the fact that holes in the covers are 0.5 mm smaller than the diameter of the bolts. This is done for better tightness and fixation of the bolts. For convenience, you can insert one cover into another and drill holes in pairs.

On the side of each cover we make holes for the wire. You can make one hole if the wire section is small. In this case, a wire with thickened insulation is used, and therefore a hole is made for each core of the wire.

We insert the bolts into the large cover, pass the wires through the side holes.

We solder the ends of the wire to the washers, and put these washers on the bolts.

We install additional washers on top.

We fix this whole “sandwich” with nuts 🙂

We dress the second cover on the bolts.

We fill the space between the two covers with sealant or hot melt adhesive, thereby ensuring hull waterproofing, And extra weight the whole structure for better contact with the surface where the sensor will be installed.

This is what a finished water detection sensor looks like, assembled from improvised materials. Nothing complicated 🙂

One or more such sensors can be connected to, the assembly process of which was described in. Also, a similar sensor can be used in a protective system for low-power pumps.

Unexpected water leakage not noticed in time can cause a lot of harm. The presented homemade water leakage sensor allows you to detect spilled water on the floor and notify about it anywhere.

The design of the water leakage sensor circuit provides two levels of control: the first triggers an alarm sound signal, the second (built-in relay) can, for example, turn on the pump or shut off the solenoid valve.

The location of the sensor can be arbitrary, while changing the length of the measuring electrodes. The scheme will be active until the flooding is eliminated. It will be enough to use three small pieces of wire as measuring sensors.

Material: ABS + metal + acrylic lenses. LED lights...

Initially, the scheme was designed to pump out water in the basement during flooding. When the first electrodes were closed, the pump in the basement was turned on, which pumped water out of it. But some situations required the intervention of residents, so there was a need for a sound notification. Often these were situations where there was simply too much water for the pump to handle.

The operation of the leakage sensor is based on the detection of a decrease in resistance between the electrodes „E1” and „E2” and „E1” and „E3”, which decreases as a result of current flow through the liquid (water).

In rest mode, there is a low level signal at the bases of the transistors, for this reason the transistors are locked. When water appears between the electrodes, it causes the appearance of a positive voltage at the bases of the transistors and, as a result, the operation of an audible signal or a relay.

IN country house, especially not intended for permanent residence, a leak from the water supply can have very serious consequences. On the market protective systems there are many ready-made solutions, however, today we will talk about building a leakage protection scheme on our own.

General description of the system

There are two main topologies of leak protection systems. The main difference between them is the way the signal is transmitted between the sensor, controller and actuators. Systems using wired transmission are simpler and more reliable, but it is not always convenient to use them when the places of possible leaks are far from each other, when the signal may not be recognized by the controller due to the considerable length of the cable. In turn, wireless systems do not require cabling, so that decorative finishes will not be disturbed during installation, but such protection is more expensive.

In wired systems, the connection between the leakage sensor and the controller is carried out via a three-wire wire. In addition, actuators are connected to the control output of the controller: electric shut-off valves, light and sound signaling devices. If desired, the scheme can be supplemented with communication devices to alert the user through a mobile or home wireless network.

circuit diagram protection against water leaks: 1 - control unit; 2 - radio module; 3 - ball electric drive; 4 - inlet taps; 5 - wired sensors; 6 - radio sensors

The main difference between the wireless system is that a radio communication module is installed together with the flood sensor. This does not require a wired connection between the controller and the sensor, however, the leak detector itself and the transmitter need a stabilized power supply from outdoor unit or batteries. Shut-off valves can also be controlled by radio, but often this is not required, because it is much easier to install the controller next to the actuator.

Controller selection

The brain of the system is the electronic control unit. Its main function is to accurately recognize a change in the signal level from the sensor and apply voltage to the actuator. At the same time, it is important that the controller has the function of recovering from emergency mode after the cause of the leak has been eliminated. As you can see, the logic of the controller is quite simple, and therefore even the simplest devices, including handicraft ones, can be used. In general, there are three options.

Relay modules are the simplest class of control devices for connecting one or two sensors. There are a number of disadvantages: the lack of state retention when the power is turned off, the need to convert the signal from the sensor to the correct level and provide the circuit with a manual reset shunt to hold in the emergency mode. However, this is the most budgetary option for building a circuit. Suitable solutions include Omron relay modules and Arduino expansion boards, as well as more expensive programmable relays such as OWEN PR110 for connecting up to 12 sensors.

Programmable logic controllers are the most versatile type of control devices that allow implementing more complex algorithms for the operation of a leakage protection system and interconnecting them with other automation systems. For the same purpose, cheap single-board computers such as Arduino can be used, with the help of which functions such as forced draining of water from the washing machine tank can be implemented.

One of the channels of a home automation or fire alarm controller can be used to connect a flood sensor. The only problem is that the type or level of the signal at the output of the sensor does not match, so it often becomes necessary to supplement the circuit with an amplifier or a single-channel discrete converter.

An example of a leakage protection circuit on Arduino

The simplest control device can also be made by hand from common electronic components. Amplification of the signal from the sensor can be implemented on transistors marked Logic Level (IRL series), which use very low voltages (about 2-3 V) for control and are capable of switching up to 20 A of load current. To avoid accidental operation, a 300-500 ohm pull-up resistor is installed between the gate and the source. It is desirable to supplement the circuit: limit the control signal with a zener diode to 50-70% of the maximum gate-source voltage, and also provide a shunt with a voltage divider between the source and the gate to hold the key in the open state. It is necessary to install an emergency reset button in the shunt circuit break. Such a circuit can have an almost unlimited number of transistors and, accordingly, control a number of actuators and indicators.

Leak sensors

The leak detector has a simple, if not primitive device. Its two main elements are a pair of electrodes, when wet, which closes the circuit, as well as a signal amplifier, which is usually a bipolar transistor with a low saturation current. The sensor is powered by two wires, the third alarm signal is transmitted to the control unit. Some sensors have built-in sound and light alarms, and a galvanically isolated switch in the form of a relay can be installed in one housing to supply power directly to the actuator.

The most common, primarily due to their low cost (about 500 rubles / piece), are considered to be the sensors "H2O Contact", "Aquarius-R" and Equation. They have several versions for connection both to analog inputs of control devices and to inputs of the "dry contact" type in normally open and normally closed states. The detectors have a built-in signal indication, but their main drawback is that they are not capable of switching a significant load, that is, they cannot directly control the valves.

Water leakage sensors: 1 - "Vodoley-R"; 2 - "H2O Contact"; 3 - Equation

More advanced, but also more expensive (from 1.5 to 2.5 thousand rubles) sensors are Ajax LeaksProtect, Ezviz T10, Neptun RSW + and other wireless devices. As a rule, these detectors are powered by a Krona battery, some models have a duration battery life may be up to two years. Most of the detectors are designed to work as part of the protection system of the same manufacturer, for some the operating frequency is indicated and it is possible to configure it for connection to universal radio receivers. A certain part of autonomous models works in the alarm mode - it emits a sound signal or sends a notification via mobile communications when a leak is detected.

Wireless water leakage sensors: 1 - Ajax LeaksProtect; 2 - Ezviz T10; 3 - Neptune RSW+

In everyday life, not individual sensors, but kits for mounting leak protection systems have gained the greatest popularity. They can include up to three sensors, one or two electric valves, a power supply and a central control unit. Similar kits are supplied to the market under the trademarks Neptun, Akvastor and Gidrolock.

Water leakage protection system "Aquastorage Classic 2x20"

Executive and auxiliary devices

The third element of the system is a device that shuts off the water supply when a leak is detected. For this purpose, either motorized ball valves or electromechanical valves are used.

Ball valves with a motor are controlled by a three-wire circuit, so they can often only be used in systems controlled by a full-fledged controller, because in addition to the closing signal, an opening signal must be given when the system is restored to its original state. However, the signal to open can be given through the reverse contact of the relay or manually through the button - a kind of replacement for resetting the alarm.

Electromechanical valves OK open type act once when a control signal is applied and block the duct. In this case, the voltage on the control channel can remain indefinitely, because during operation the circuit is opened by a contact group mechanically connected to the valve stem. It must be remembered that it is the normally open valve that, after the protection is triggered, remains in this position even in the event of a power failure and is cocked manually after the leakage has been eliminated.

Actuators do not have to be specialized; any taps or valves for plumbing systems will do. However, you need to pay attention to the operating voltage range, because some relay modules cannot control direct current, and the switching outputs of the controllers can only work with limited voltage and current.

Auxiliary devices may also be present in the circuit:

1. Radio communication modules - a set of transmitter and receiver, for example, the MX series at 433 MHz, will allow you to create a wireless connection between the sensor and the control unit using equipment designed to build systems with wired communication.
2. Signal amplifiers and modulators are designed to match the logic levels between the sensors and the control unit. As amplifiers, single-board modules based on the LM358 chip are most popular, for signal conversion - modular DAC / ADC based on PCF8591.
3. Intermediate relays will be useful if the relay group of the control unit does not allow switching currents of significant magnitude. Relays designed for low control voltage - 24 or 36 V are most preferred.

Circuit assembly and installation

There is no difficulty in installing a leak protection system if a ready-made kit is used: all elements are fully compatible, the connectors fit each other, there is detailed instructions. Assemblies of an individual configuration are more difficult to implement, so we will consider the topology of a protection system with two sensors and wireless communication.

The “H2O Contact” will be used as a flood sensor in a four-wire version with a normally open contact. Brown (+) and white (-) wires are connected to a power source - a 9 V battery. One of the remaining wires is connected to the power plus, the other to the TX DATA pin of the MX-FS-03V radio transmitter. Solder 10-15 cm to the ANT pad on the transmitter board copper wire coiled up into a spiral. The sensor is attached with screws or double-sided tape, the electrodes must be firmly pressed to the floor. The wire from the sensor runs along the wall to a small plastic case that houses the radio transmitter and power supply.

Wiring diagram for a leak protection system with two sensors and wireless communication

The radio receiver MX-05V is installed near the control device, which will be used as a programmable relay module FRM01. The RX terminal of the radio receiver is connected to the IN input of the LM358 amplifier module, the GND and VCC terminals are connected to the negative and positive 5V power supply. The amplifier module also needs 12V power through the VCC and GND terminals. The output from the amplifier module is connected to the input terminal of the relay module IN, which is also connected to a 12V power supply (the circuit is reverse polarity protected).

As executive device it is recommended to use the ball valve NT9047 with 24 V supply voltage, which is installed at the inlet of the water main. The neutral wire of the tap is connected to the minus of the power source, the wire of the closing contact is connected to the normally open output of the relay, the opening one is connected to the normally closed one. The relay must be configured according to the instructions - set function number 10. As you can see, the entire assembly requires three voltage levels for operation, which is solved by purchasing several cheap power supplies for 5, 12 and 24 V, the latter with a current of up to 2 A.

Related videos

An unpleasant situation with flooding of your home, as well as apartments located on the lower floors, can be avoided by installing a system that shuts off the inlet valves when moisture appears on the floor of the room. Such devices, designed specifically for domestic use, have been on the market for a long time under the generic name "leak protection systems". The widespread distribution of these devices is hindered by their high cost associated with the presence of imported components and assemblies. Self-assembled leak protection , is devoid of this drawback and can be made from parts that can be found in any garage.

Consider two types of devices: mechanical and electronic. The first fixture is very easy to make. The second will require some knowledge of electronics and skills in working with a soldering iron. Both devices have been repeatedly repeated by home craftsmen and have earned the reputation of inexpensive and effective systems for protecting against water leaks.

Homemade paper-spring mechanism

Water leakage protection device by the inventor Rudik A.V.

The self-made mechanism, which was invented by the inventor Alexander Vladimirovich Rudik, is somewhat reminiscent of a mousetrap. Its design includes an intricately crafted metal case, a spring, paper tape and a cable attached to a ball valve that shuts off the water supply. This mechanism works as follows: when the paper tape is soaked due to moisture getting on it, it breaks and releases the tensioned spring. Compressing, the spring pulls the cable, which, in turn, closes the valve.

Alexander Rudik's mechanism is a bit like a mousetrap

The advantage of such a device is that intervention in the plumbing system is not required, since ball valves already mounted in it are used. In addition, if necessary, nothing prevents the manual closing of the valves.

Cable installation

The leak protection device can be installed anywhere: in the kitchen under the sink, in the bathroom or in the toilet. Its design allows the use of two cables to simultaneously stop the supply of cold and hot water. The mechanism does not require any maintenance.

Production of a leak protection mechanism

To make a leak protection device, you will need:

• Locksmith vice;
• Hacksaw for metal;
• Drill;
• Hammer
• pliers;
• Electric grinder.

Of the materials, you should stock up on sheet metal (preferably galvanized or stainless steel). You will also need: a cable, suitable wooden block dimensions 360x50x30mm, spring, paper, screws, stationery buttons.

Scheme of cutting a metal sheet

The basis of the mechanism is a bar, the edge of which is cut along the short side at an angle of 93 °. Elements 3, 4, 5 are mounted on it, as well as a spring and a cable.

A paper strip is used as a sensitive sensor, which is attached to wooden base buttons.

Plain paper is used as a signaling device

To make element No. 3, you can use a durable bar with dimensions of 150x20x50mm. The blank cut from the sheet is bent around this bar, cuts are made for installing the cable, and then removed from the wooden fixture.

The third and fourth structural elements are best made of stainless steel, as this material has a more slippery surface. The places where the parts need to be bent are shown in the drawing with red lines.

In the slots of parts 4a and 4b, install the cable

A cable is installed in the slot of parts 4a and 4b. Then parts 4, 4a, 4b and the spring must be connected from below with a screw.

Mechanism adjustment

It is convenient to manufacture and adjust the device using a simple fixture, simulating part of the water pipe. To do this, you need a 20 mm pipe with a threaded part, on which you need to install a ball valve.

Bracket for fixing the mechanism to the pipeline

With the help of such a device, you can check and adjust the operation of the mechanism right in the workshop. You will also need a pipe when drilling holes in elements 2 and 2a. To do this, a pipe is installed between them and the parts are clamped in a vice. At the same time, make sure that the crane handle (element 1 and 1a) is in the closed state, and the grooves for the cable and element 2 are aligned. After that, start drilling the through holes of elements 2 and 2a.

The crane handle will allow you to adjust the operation of the mechanism directly in the workshop

Element 5 has a hole for a finger (for installing a spring) and a hole for a hook. By scrolling through the turns, with part 5, you can adjust the spring stiffness.

The mechanism in the "charged" state

The tension force of the spring in the working position must be at least 10 kg. The main condition: the force on the paper tape should be 1-1.5 kg. To measure its value, you can use household spring scales ("canter"). If necessary, the amount of effort can be changed by decreasing or increasing the angle at the short end of the bar. The same angle should be for elements 3,4 in the area of ​​contact.

Spring bracket with finger hole

A good spring is obtained by cutting off the necessary piece from a door spring, which are sold at any hardware store. The cable can be used bicycle, shortening it to the desired length.

To check the performance of the assembled system, the paper tape is moistened with water. When soaked, it should break and release the spring mechanism.

Requirements for the installation of a mechanical leakage protection system

If the mechanism has worked, the subsequent installation of the paper tape should be carried out only after complete removal of moisture from the surface of the device.

The cable should have a length of no more than 2 m, while its numerous bends should be avoided (no more than one bend at a right angle is allowed).

It is necessary to fix the bracket to the pipe rigidly, therefore it is better if the pressure pipeline is made of metal pipes.

This is what the drive mechanism looks like.

The ball valve must be of good quality. Resistance to the closing force and jerks while turning its handle are not allowed.

The operation of the leakage protection mechanism (video)

Electronic anti-flood system

The electronic system consists of at least three blocks. This is a leakage sensor installed on the floor of the room, a control unit and an actuator.

Such a system works as follows: when moisture appears, the circuit between the sensor electrodes closes. This instructs the control unit to supply voltage to the electric drive, which shuts off the water supply. The leakage sensor and control unit can be made independently. As an executing mechanism, you will need an electrovalve or a ball valve with a servo drive.

Sensor manufacturing

The simplest leakage sensor is two conductors located at some distance from each other. However, you must agree that bare wires on the bathroom or toilet floor will look at least ridiculous, and at most provide a danger of injury. electric shock. Therefore, it is possible to manufacture a sensor by etching tracks on printed circuit board from foil textolite, and use the doorbell button as a case.

Using the doorbell housing as a leak detector

The work should be done in the following order:

• Cut the board to the size of the button;
• Using the LUT method or using a photoresist, it is necessary to etch the tracks on the surface of the boards;
• Tin the printed conductors with a soldering iron;
• Solder staples to the conductors as legs;
• Connect the connecting wire;
• Install the printed circuit board in the bell button housing.

PCB layout

At the same time, the button itself does not need to be dismantled; with its help, you can close the line to check the system's performance.

Electrical diagram of the control unit

The system is powered by a small 12V battery. The main requirement for a power supply is its low self-discharge. Since the current consumed by the circuit in standby mode is negligible, the battery will have to be recharged literally a couple of times a year.

Close control scheme ball valve works as follows. In standby mode, there is no current through the sensor, the transistors are closed, the relay is de-energized. When water appears on the base of transistor VT1, a bias voltage appears, as a result of which the transistor opens and supplies power to the base of a more powerful transistor VT2. In turn, the open transistor VT2 controls an electromagnetic relay that supplies power to the actuator.

An example of a control circuit for closing a ball valve

Transistors can be used in an electrical circuit n-p-n structures with any label. Transistor VT2 should be of medium power. Resistors R1, R2 are low-power.

The improved electrical circuit is shown in the following figure. It is designed to connect two motor-reducers.

An example of an improved electrical circuit

Executing mechanism

Of course, the actuator can be assembled by yourself using a suitable gear motor and limit switches. However, it will be easier and more reliable to purchase a factory-made ball valve with a servo drive. When purchasing such a device, make sure that its design provides for limit switches that open the circuit in extreme positions.

Of course, the price of these devices is much higher than plastic counterparts, but the reliability of their work is not satisfactory.

Actuating mechanism

After connecting the sensor, control unit and electric tap to the power source, the system is tested. To do this, pour a little water on the sensor installation site.

One of the most common problems in urban apartments today is flooding. This is fraught with damage not only to one's own, but also to neighboring property. But what about people who cannot stay at home all the time and monitor taps and pipes? Perfect solution in this case, these are do-it-yourself water leakage sensors. How to make a sensor that reacts to moisture, and what components do you need for this?

The principle of operation of detectors

Water leakage sensors work on the principle of excellent electrical conductivity of water. The structure of each sensor includes contacts in the amount of two or three pieces. As soon as liquid enters these contacts, a circuit is closed between them, which leads to the operation of the leakage sensor. For maximum efficiency sensors should be installed in places where the likelihood of leakage is highest - in the bathroom, under the sink, etc.

It is worth talking about the classification of sensors according to the principle of operation. According to this criterion, they are divided into three types:

Autonomous. These are completely independent devices that emit loud sound signals in case of flooding. Also on sale you can find models with a built-in GSM module, with the help of which notifications are sent to the owner of the dwelling about a detected water leak.

Wired. They are connected to the central control unit using a signal wire.

Wireless. Such sensors, after detecting a water leak, send radio signals to the remote control.

For the most part, water leak detectors are point devices, that is, they register a leak in a specific place. To track a large area, it is recommended to use tape sensors.

Self-Assembly Option #1

The cost of modern liquid leakage sensors is not so high that even one such sensor could not be afforded. However, the device device is not so complicated, so you can save money and assemble the desired device yourself from a set of electronic components. Below you can see one of the easiest and cheapest ways to make a water leak sensor with your own hands.

To assemble the sensor, you will first need plastic bottle. You also need the following components:

• Coin-cell battery with supply voltage up to 3V - for example CR1632.
• Transistor BC517 or BC816 with NPN - a composite transistor is required.
• 1-2 MΩ resistor, or several pieces with a total resistance of 1-2 MΩ.
• Piezo emitter with a generator, necessary for sound notification.

When all the components from the list above are prepared, you can start assembling the simplest sensor.

Device Assembly Order

The scheme of the device under consideration for monitoring water leaks is extremely simple, as is the algorithm for assembling it:

Solder the contact of the piezo emitter to the collector of the transistor.

Solder the resistor to the base and emitter of the transistor between them.

Connect the transistor and the second contact of the piezo emitter to the battery.

Place all components in a case made from part of a bottle with a cap.

Bring two contacts out of the cover - a contact from a resistor and a piezoelectric emitter.

This completes the self-assembly of the device. The principle of operation is simple - when moisture gets simultaneously on both contacts brought out of the cover, electrical circuit closes. The piezo emitter begins to emit a loud high-pitched squeak, which notifies the detection of a liquid leak. Place this device in the expected places of leakage - under washing machine, sink, batteries, etc.

Self-Assembly Option #2

Your option is simple and cheap, but its possibilities are severely limited. You can spend a little more time and electronic components and make a more advanced water leak sensor yourself. For this option, you will need a soldering iron, solder, textolite, as well as the following components:

• chip LM7555;
• LED of any color;
• 6 resistors for 10 and 100 kΩ;
• 2 capacitors;
• 1 transistor and a booster with a generator.

Also, to assemble this device, you will need single-core and stranded connecting wires.

Device Assembly Order

You can place all the electronic components of the sensor in question on a printed circuit board measuring only 22 by 12 millimeters, or on a breadboard of similar dimensions. A sketch of the required board can be seen below:

In the role of contacts, with the help of which the sensor is triggered by water, two pieces of tinned wire act. They are connected to the circuit through resistors of 10 and 100 kΩ. More details on the diagram:

The main advantage of this sensor lies in the two available modes of operation. The device can work both completely autonomously, giving sound signals when water is detected, and as part of a security system. If you stick to the first option, the above scheme can be implemented without changes. However, when using sensors as part of a security complex, it is better to remove the boozer from the circuit and connect all sensors in series using a signal wire. Further, this wire is connected to the main security console.

Self-Assembly Option #3

You can consider another version of a home-made device for determining fluid leakage. It is based on the use of the K561LN2 chip. In addition to it, the following components will be needed to assemble the device:

• bipolar transistor KT3107D;
• seven resistors with ratings from 57 KΩ to 3 MΩ;
• polar capacitor 100 microfarads;
• four capacitors for 0.1 Mk and 0.01 Mk;
• current source with a voltage of 6 to 9 volts;
• piezo emitter ZP-22.

The diagram of the device is presented below - you need to assemble all the electrical components in the system in accordance with it.

The circuit presented above is characterized by low power consumption, accuracy of operation, as well as a loud sound alert when a leak is detected. It won't take long to make it.

There are many other electrical circuits, according to which you can independently make a liquid leakage sensor to protect your home from flooding. You can also buy and install ready-made solutions.