Sometimes human laziness can make you think, so to speak, create. And they came up with the wheel, probably out of laziness, when they got tired of carrying everything on themselves.
So I’m tired of standing in front of water barrels filling with water. Summer is dry, there are 4 barrels, each fills in about half an hour. It’s too lazy to entangle the area with wires from the level sensors, and making a control unit in such heat. I tried to let this matter take its course, but at the fifth step from the barrel I already forgot that the barrel was being filled and the pump was on. I started thinking about how to make a wireless barrel fill alarm. I thought for a long time until the radio call came through the gate. Everything that immediately came to mind, look at photo 1. 
The entire structure required two welding electrodes and an empty alcohol bottle. In short, everything that came to hand. I hope you find it all more aesthetically pleasing. First, a rocker arm is made and a float is attached to it. Then they make a blank for the bracket. They cut off a piece of the electrode of the required length, sharpen it on both sides and bend it in the shape of the letter “L”, put a rocker arm with a float on one end and then bend this end to form a bracket. Next, this bracket is hammered into the board. It took me about twenty minutes to do everything. The call button on the board just lies there. I hope the principle of operation of the entire device is clear. The water is poured, the float rises, the rocker presses the button, the bell rings, you run out of the house and transfer all the equipment to the next barrel. The disadvantage here is that the call is powered from a 220V network. It wouldn’t be a bad idea to switch it to autonomous power supply, then you’ll be able to catch crucian carp in the pond for a whole half hour. Good luck. K.V.Yu.
Country house. Well with pump + storage tank. If you are too lazy to turn on the pump, then you need an automatic switch. The task is as follows: it is necessary to turn on the pump in the well when the water in the storage tank (for example, a barrel) drops below a certain level, and turn off the pump when the water fills up.
Storage containers come in different sizes. Wells are also different. You can inadvertently drain the well if you do not turn off the pump in time. And the pump itself is also not accustomed to working without water.
Therefore, you also need to be able to temporarily turn off the pump in the well if the level has dropped and allow it to turn on if the level is normal.
There are many on the Internet electronic circuits monitoring the upper and lower water levels. From simple ones (a couple of transistors) to microprocessor ones. We will not consider them. The principle of electrical conductivity of water is very often used as a water level sensor. Those. These are, as a rule, electrodes in direct contact with water. The downside is that they tend to oxidize, lose contact with wires, and other benefits of having a “piece of hardware under potential” in water.
This article discusses the implementation of a contactless sensor from scrap materials.
After my pump failed to turn on once again, I decided to make something more original as a sensor than three pieces of iron in the water.
To make one such sensor you will need:
- Polypropylene pipe for water with an internal diameter of 25mm. A pipe made of metal-plastic is not advisable, because... it can be accidentally deformed quite easily, but if you are careful, you can do it.
- A pair of door opening sensors (we remove two reed switches and a magnet from them)
- Cork stopper from a bottle (wine or other suitable one). The contents of the bottle are not so important, the main thing is that it does not interfere with further work.
- A wire of the required length, heat-shrink tubing, a pair of nylon ties, string and electrical tape.
In general, there was nothing in short supply, everything was found in the barn.
The first thing you need to do is drill (pick) a hole in the end of the plug to insert a magnet inside.
After the magnet is inserted, you need to check that the plug flies freely inside the pipe. Most likely this is not the case. Therefore, by rubbing the cork against a file or sandpaper, we reduce the diameter of the cork.
It should look something like this:
For better sliding inside the pipe, the cork can be coated with varnish (for example, yacht varnish) using the dipping method.
Because The varnish will add some thickness to the cork; you need to adjust the diameter of the cork with a margin. I have the diameter of the plug along with varnish coating less than the inner diameter of the pipe by about 3 mm.
Next, we solder the obtained reed switches to the wires, place them in heat shrink and encase it. The distance between the reed switches corresponds to the difference between the lower water level in the well (when the pump needs to be turned off in an emergency) and the upper level when it is allowed to be turned on again.
To prevent water from penetrating inside, the upper edge of the heat shrink should go over the wire and grip it tightly. Therefore, it is better to use a round wire.
The heat shrink should go from the wire suitable to the sensor over both reed switches and end approximately 5 cm after the lower reed switch.
We make the lower edge of the heat shrink about 5 cm larger than necessary and after shrinking we bend the tail upward, fixing it in this position, for example, with another piece of heat shrink.
We collect. Heat-shrinkable reed switches are attached along the tube using any convenient method (nylon ties or electrical tape). When using screeds, it must be taken into account that cold water they can shrink and either burst themselves or damage something. Therefore, you should not tighten them too much.
There is exactly the same limiter on top so that the plug does not float out of the pipe. The limiters must be placed in such a way that, when resting against them, the plug is opposite the reed switch.
Like that:
The assembled structure needs to be tied to a rope and can be used.
It turns out like this:
Before lowering it into the well, we connect everything to the pump control device and check its functionality by turning the pipe over.
The plug should move freely and when it reaches the reed switches, turn the pump off/on.
We lower the pipe into the well to the end (the lower reed switch is just below the pump level). We turn on the pump and try to drain the well. As soon as the pump begins to gasp for air, raise the tube until the plug drops to the lower reed switch and turns off the pump.
Raise it a little higher so that the pump turns off a little earlier than the water runs out and fix it like that. Accordingly, when there is enough water in the well, the plug will turn on the upper reed switch, which allows the pump to work again.
A similar device is installed on the storage tank. It turns on the pump when the water in the tank runs out and turns off when the water is full.
True, this device has some technological features:
- The device is not located inside the container, but outside and works using the method of communicating vessels.
- In this case, you don’t have to install the upper limiter; it is enough for the pipe to be slightly higher than the top edge of the container
- It will not be possible to use two holes and a tie as a lower limiter (water will leak out). Therefore, the lower limit is the bend of the pipe.
Unfortunately, it was not possible to photograph the actual structure installed on the drive. Therefore, I will show you schematically.
Hi all. Today we will talk about a very simple set for self-assembly device for monitoring water level. This set can be successfully soldered by a student in grades 5-7 in one evening. Of course, you can do it completely yourself, including the board, but I decided to save time, so I ordered a kit.
The set was purchased with the goal of somehow automating the collection of water into a barrel at the dacha. Moreover, this is not exactly a barrel, but rather a pipe going down 2.5-3 meters, so the water reserves there are decent (for simplicity, let there be a barrel). The idea was simple, while there is no regular water supply, the electric valve opens and fills the barrel with water at a given level. Consumption of water in buckets as needed and automatic refilling into the barrel. To ensure that the valve does not often operate due to water fluctuations, several levels are designed. The lower one at which the valve turns on and the upper one at which it turns off. Those. there is a certain dead zone in which there is water flow, but there is still no water supply to the barrel. By the way, this dead zone is actually such a thing as hysteresis.
Last year, this function was performed by such a sorry device as a float mechanism from the toilet cistern. It worked properly and occasionally became clogged, since the water comes through pipes straight from the river. But in the end, it didn’t survive the winter because it was made of plastic and fell apart from the frost.
This set was intended to replace a failed mechanism.
While storing the assembled board and waiting for the summer season, an attempt was made to use the assembled board in production, on this installation. 
This is just a large saucepan with a heating element type heater with a power of 27 kW. The products are taken out of the refrigerator in whole pallets and placed in a saucepan. It all needs to be heated to 90 C. Can you imagine how much electricity is wasted every day?!
To estimate the volumes, I will attach a couple of photos:
The products, by the way, are pork stomachs and curly (part of the intestines).
As far as I know, the stomachs are stuffed with something and eaten, and the intestines are about the same - including sausages.
This thing is cooked and re-frozen. Next it goes to China. This is the cycle of goods in nature. We give them natural by-products, and in return we give them electronics...
The question has arisen to switch the heating of the pan to steam. It's more economical and the power is higher. Productivity increases significantly. This is where a level sensor was needed so that no one would be scalded by the steam and steam would be supplied only when there was at least a minimal amount of water in the container.
However, I realized it in time and refused final installation, although tests showed the board's functionality. It is contraindicated to use homemade products in production. Therefore, they found it less quickly the required device, which performs the same functions, but also has a certificate. The operating principle of the factory device practically corresponds to the set from the online store and, in a particular case, performs the same functions.
This device domestic production Aries SAU-M7. 
Delivery and packaging:
Bangood is very stable, a small package and several layers of polyethylene foam. 
In a small bag there is a “bunch” of parts, a board and wires.
I didn’t sort by denominations, I just laid them out for clarity.
The scheme is not simple, but very simple. 4 2I-NOT elements are used, with two of them serving as a trigger. It is needed to form a hysteresis loop.
Pins 1 and 2 of J3 provide a low level signal and turn on the relay. Contacts J4 1 and 2 are the upper level and emergency; when any of them is triggered, the relay turns off. The relay operation is duplicated by lighting the LED. The scheme works reliably on tap water and just as confidently in water after water treatment, which contains less salts.
I assembled the board almost without looking at the diagram, except to look at the resistor values.
It is unlikely that the pins will be mixed up, and even the installation of parts such as connectors or transistors will be prevented by the silk-screen printing.
The only drawback during installation is that I mixed up the LEDs. But this is so, little things do not affect performance.
Homemade conductometric type level sensors were used as sensors. This is roughly what they look like assembled:
On the side of the board where the parts are installed, there is silk-screen printing, which is quite high quality. 
The process of unsoldering parts will not be of interest to you, since I am not an assembler and do not know the specifics of the board assembly process. Whatever came into my hand from the edge, I soldered it.
The printed circuit board is covered with a protective mask on the solder side. There is no metallization. The fee is one-sided.
I used solder type POS 61 with rosin. I screwed up a little. 
I fixed the power wires with sealant so that they would not break off at the exit from the holes. The wires that came with the kit seemed too short to me. 
I washed the board with a solvent and alcohol and covered it with a layer of Plastik 70. I immediately noticed the difference between my previous boards and this one. The surface is shiny and the contacts are covered with a layer of film.
There was some inconvenience, which is actually a plus. I wanted to make a video about the operation of the board using a multimeter, but I got a problem in the form that the chips simply do not push through the protective coating. That's why there is no multimeter in the video. 
Video demonstrating the board's operation:
Upd: While I was writing the review, I didn’t even pay attention to the product page, as usual. And only after writing the review did I pay attention to the product. The payment does not match the one that was sent to me and judging by the comments, many are sent two different options fees. This does not affect the functionality. Both boards are functional.
Results: The simplest set, available for schoolchildren, also has practical use. I recommend it for purchase. There was a slight residue left due to the fact that the board received was not the one in the description.
In my case, the wires turned out to be redundant. They were probably planned to output LEDs from the board to the front panel and connect a power source.
I'm planning to buy +52 Add to favorites I liked the review +25 +47To automate many production processes it is necessary to monitor the water level in the tank; the measurement is carried out using a special sensor that gives a signal when the process medium reaches a certain level. It is impossible to live without level meters in everyday life, shining example This means shut-off valves for the toilet cistern or automatic equipment for turning off the well pump. let's consider different kinds level sensors, their design and operating principle. This information will be useful when choosing a device for a specific task or making a sensor yourself.
Design and principle of operation
The design of measuring devices of this type is determined by the following parameters:
- Functionality, depending on this device, is usually divided into alarms and level meters. The former monitor a specific tank filling point (minimum or maximum), while the latter continuously monitor the level.
- The operating principle can be based on: hydrostatics, electrical conductivity, magnetism, optics, acoustics, etc. Actually, this is the main parameter that determines the scope of application.
- Measuring method (contact or non-contact).
In addition, the design features are determined by the nature of the technological environment. It's one thing to measure height drinking water in the tank, another is to check the filling of industrial wastewater tanks. In the latter case, appropriate protection is necessary.
Types of level sensors
Depending on the principle of operation, alarms are usually divided into the following types:
- float type;
- using ultrasonic waves;
- devices with capacitive principle level determination;
- electrode;
- radar type;
- working on the hydrostatic principle.
Since these types are the most common, let's look at each of them separately.
Float
This is the simplest, but nevertheless effective and reliable way measuring liquid in a tank or other container. An example implementation can be found in Figure 2.
Rice. 2. Float sensor for pump control The design consists of a float with a magnet and two reed switches installed at control points. Let us briefly describe the principle of operation:
- The container is emptied to a critical minimum (A in Fig. 2), while the float drops to the level where reed switch 2 is located, it turns on the relay that supplies power to the pump pumping water from the well.
- The water reaches the maximum level, the float rises to the location of reed switch 1, it is triggered and the relay is turned off, respectively, the pump motor stops working.
It’s quite easy to make such a reed switch yourself, and setting it up comes down to setting on-off levels.
Note that if you choose the right material for the float, the water level sensor will work even if there is a layer of foam in the tank.
Ultrasonic
This type of meter can be used for both liquid and dry media and may have an analogue or discrete output. That is, the sensor can limit the filling upon reaching a certain point or monitor it continuously. The device includes an ultrasonic emitter, receiver and signal processing controller. The operating principle of the alarm is demonstrated in Figure 3.
Rice. 3. Operating principle ultrasonic sensor level The system works as follows:
- an ultrasonic pulse is emitted;
- the reflected signal is received;
- The duration of signal attenuation is analyzed. If the tank is full, it will be short (A Fig. 3), and as it becomes empty it will begin to increase (B Fig. 3).
The ultrasonic alarm is non-contact and wireless, so it can be used even in aggressive and explosive environments. After initial setup, such a sensor does not require any specialized maintenance, and the absence of moving parts significantly extends its service life.
Electrode
Electrode (conductometric) alarms allow you to monitor one or more levels of an electrically conductive medium (that is, they are not suitable for measuring the filling of a tank with distilled water). An example of using the device is shown in Figure 4.
Figure 4. Liquid level measurement with conductometric sensors In the example given, a three-level alarm is used, in which two electrodes control the filling of the container, and the third is an emergency one to turn on the intensive pumping mode.
Capacitive
Using these alarms, it is possible to determine the maximum filling of the container, and both liquid and bulk solids of mixed composition can act as the process medium (see Fig. 5).
Rice. 5. Capacitive level sensor The operating principle of the alarm is the same as that of a capacitor: the capacitance is measured between the plates of the sensitive element. When it reaches the threshold value, a signal is sent to the controller. In some cases, a “dry contact” design is used, that is, the level gauge operates through the tank wall in isolation from the process medium.
These devices can operate over a wide temperature range, are not affected by electromagnetic fields, and can operate over a long distance. Such characteristics significantly expand the scope of application up to severe operating conditions.
Radar
This type of alarm device can truly be called universal, since it can work with any process environment, including aggressive and explosive ones, and pressure and temperature will not affect the readings. An example of how the device works is shown in the figure below.
The device emits radio waves in a narrow range (several gigahertz), the receiver catches the reflected signal and, based on its delay time, determines how full the container is. The measuring sensor is not affected by pressure, temperature or the nature of the process fluid. Dustiness also does not affect the readings, which cannot be said about laser alarms. It should also be noted high accuracy devices of this type, their error is no more than one millimeter.
Hydrostatic
These alarms can measure both maximum and current filling of tanks. Their operating principle is demonstrated in Figure 7.
Figure 7. Fill measurement with gyrostatic sensor The device is built on the principle of measuring the level of pressure produced by a column of liquid. Acceptable accuracy and low cost made this type quite popular.
Within the scope of the article, we cannot examine all types of alarms, for example, rotary-flag ones, for identifying granular substances (a signal is sent when the fan blade gets stuck in a granular medium, after first tearing out the pit). It also makes no sense to consider the principle of operation of radioisotope meters, much less recommend them for checking the level of drinking water.
How to choose?
The choice of a water level sensor in a tank depends on many factors, the main ones:
- Composition of the liquid. Depending on the content of foreign impurities in the water, the density and electrical conductivity of the solution may change, which is likely to affect the readings.
- The volume of the tank and the material from which it is made.
- The functional purpose of the container is to accumulate liquid.
- The need to control the minimum and maximum level, or monitoring of the current state is required.
- Admissibility of integration into an automated control system.
- Switching capabilities of the device.
This is far from full list for selection measuring instruments of this type. Naturally, for domestic use it is possible to significantly reduce the selection criteria, limiting them to the volume of the tank, the type of operation and the control circuit. Significant reduction in requirements makes it possible self-production similar device.
Making a water level sensor in a tank with your own hands
Let's say there is a task to automate work submersible pump for water supply to the dacha. As a rule, water flows into a storage tank, therefore, we need to make sure that the pump automatically turns off when it is filled. It is not at all necessary to buy a laser or radar level indicator for this purpose; in fact, you don’t need to purchase any. A simple task requires simple solution, it is shown in Figure 8.
To solve the problem, you will need a magnetic starter with a 220-volt coil and two reed switches: a minimum level for closing, a maximum level for opening. The pump connection diagram is simple and, importantly, safe. The principle of operation was described above, but let’s repeat it:
- As the water collects, the float with the magnet gradually rises until it reaches the maximum level reed switch.
- The magnetic field opens the reed switch, turning off the starter coil, which leads to de-energization of the engine.
- As the water flows, the float drops until it reaches the minimum mark opposite the lower reed switch, its contacts close, and voltage is supplied to the starter coil, which supplies voltage to the pump. Such a water level sensor in a tank can work for decades, unlike electronic system management.
To regulate and control the level of liquid or solid substance (sand or gravel) in production or at home, a special device is used. It is called a water level sensor (or other substance of interest). There are several varieties of such devices, which differ significantly from each other in their operating principle. How the sensor works, the advantages and disadvantages of its varieties, what subtleties you should pay attention to when choosing a device, and how to make a simplified model with a relay with your own hands, read in this article.
The water level sensor is used for the following purposes:
Possible methods for determining tank load
There are several methods for measuring liquid level:
- Contactless- often devices of this type are used to control the level of viscous, toxic, liquid or solid, granular substances. These are capacitive (discrete) devices, ultrasonic models;
- Contact- the device is located directly in the tank, on its wall, at a certain level. When the water reaches this indicator, the sensor is triggered. These are float, hydrostatic models.
Based on the principle of operation, the following types of sensors are distinguished:
- Float type;
- Hydrostatic;
- Capacitive;
- Radar;
- Ultrasonic.
Briefly about each type of device
Float models are discrete and magnetostrictive. The first option is cheap, reliable, and the second is expensive, complex design, but guarantees an accurate level reading. However general disadvantage float devices - this requires immersion in liquid.
Float sensor for determining the liquid level in the tank
- Hydrostatic devices - in them all attention is paid to the hydrostatic pressure of the liquid column in the tank. The sensitive element of the device senses pressure above itself and displays it according to a diagram to determine the height of the water column.
The main advantages of such units are compactness, continuity of operation and affordability. But they cannot be used in aggressive conditions, because they cannot do without contact with liquid.
Hydrostatic liquid level sensor
- Capacitive devices - plates are provided to control the water level in the tank. By changing the capacity indicators, you can judge the amount of liquid. Lack of moving structures and elements, simple circuit devices guarantee durability and reliable operation of the device. But one cannot fail to note the disadvantages - this is the necessity of immersion in liquid, and demanding temperature conditions.
- Radar devices - determine the degree of increase in water by comparing the frequency shift, the delay between the radiation and the achievement of the reflected signal. Thus, the sensor acts as both an emitter and a reflection collector.
Such models are considered the best, accurate, reliable devices. They have a number of advantages:
The only disadvantage of the model is its high cost.
Radar tank liquid level sensor
- Ultrasonic sensors - the principle of operation and the design of the device are similar to radar devices, only ultrasound is used. The generator creates ultrasonic radiation, which, upon reaching the surface of the liquid, is reflected and reaches the sensor receiver after some time. After some mathematical calculations, knowing the time delay and speed of the ultrasound, the distance to the water surface is determined.
The advantages of a radar sensor are also inherent in the ultrasonic version. The only thing is that the indicators are less accurate and the operation scheme is simpler.
Subtleties of choosing such devices
When purchasing a unit, pay attention to the functionality of the device and some of its indicators. Extremely important questions when purchasing a device are:
Options for sensors for determining the level of water or solids
DIY liquid level sensor
You can make a basic sensor to determine and control the water level in a well or tank with your own hands. To perform the simplified version you need:
A self-made device can be used to regulate water in a tank, well or pump.
