How to make a thermostat for water with your own hands. Let's take a quick look at both manufacturing options. Automatic room heat regulation

Successful incubation of poultry eggs is impossible without stable holding temperature regime... The thermostat for the incubator must provide an accuracy of ± 0.1 ° C, with the possibility of changing it within the range from 35 to 39 ° C. Most of the commercially available digital and analogue instruments meet this requirement. A sufficiently accurate thermostat can be made at home, subject to basic knowledge of electronics and the ability to hold a soldering iron in your hands.

In ancient times…

In the first domestic and industrial incubators of the last century, the temperature was controlled using bimetallic relays. To relieve the load and eliminate the influence of overheating of the contacts, the heaters were turned on not directly, but through powerful power relays. This combination can be found in cheap models to this day. The simplicity of the scheme was the key to reliable operation, and any high school student could make such a thermostat for an incubator with his own hands.

All positive aspects were canceled out by low resolution and complexity of adjustment. The temperature in the process must be reduced according to the schedule in increments of 0.5 ° C, and it is very problematic to do this with a precise adjusting screw on the relay located inside the incubator. As a rule, the temperature remained constant throughout the entire period of incubation, which led to a decrease in hatchability. The designs with the adjusting knob and graduated scale were more convenient, but the holding accuracy was reduced by ± 1-2 ° C.

The first electronic

The analog temperature controller for the incubator is somewhat more complicated. Typically, this term refers to the type of control in which the level of the voltage taken from the sensor is directly compared with the reference level. The load is switched on / off in a pulsed mode depending on the difference in voltage levels. Adjustment accuracy even simple schemes is in the range of 0.3-0.5 ˚С, and when using operational amplifiers, the accuracy increases to 0.1-0.05 С.

For a rough setting of the required mode, there is a jackal on the body of the device. The stability of the readings is little dependent on the room temperature and line voltage drops. To eliminate the influence of interference, the sensor is connected with a shielded wire of the minimum required length. This category also includes rare models with analog load control. The heating element in them is constantly on, and the temperature is regulated by smoothly changing the power.

A good example is the TRi-02 model - an analog thermostat for an incubator, the price of which does not exceed 1,500 rubles. Since the 90s of the last century, they have been equipped with serial ones. The device is easy to operate and is completed with a remote sensor with a 1 m cable, a power cord and a meter load wire. Technical specifications:

Load power at standard mains voltage from 5 to 500 W.
The adjustment range is 36-41˚С with an accuracy not worse than ± 0.1˚С.
Ambient temperature from 15 to 35˚С, permissible humidity up to 80%.
Contactless triac load switching.
Overall dimensions of the case are 120x80x50 mm.

In numbers it is always more accurate

Digital measuring devices provide high accuracy of adjustment. The classic digital incubator thermostat differs from the analogue in the way of signal processing. The voltage removed from the sensor passes through the analog-to-digital converter (ADC) and only then enters the comparison unit. The initially set digital value of the required temperature is compared with that obtained from the sensor, and a corresponding command is sent to the control device.

Such a structure significantly improves the measurement accuracy, minimally depending on the ambient temperature and interference. Stability and sensitivity are usually limited by the capabilities of the sensor itself and the capacity of the system. Digital signal allows you to display the value of the current temperature on an LED or liquid crystal display without complicating the circuitry. A significant part of industrial models have advanced functionality, which we will consider using the example of several modern devices.

The capabilities of the budgetary digital thermostat Ringder THC-220 are quite enough for a homemade home incubator. Temperature control in the range of 16-42 внешнийС and an external block of outlets for connecting the load allows the device to be used in the off-season, for example, to control the room climate.

For review, we present brief characteristics devices:

The current temperature and humidity in the area of \u200b\u200bthe sensor are indicated on the LCD.
The range of the indicated temperature is from -40˚C to 100˚C, humidity is 0-99%.
The selected modes are displayed on the screen as symbols.
Temperature setting step 0.1˚С.
Humidity regulation up to 99%.
24 hour timer format with day / night division.
Loading capacity of one channel is 1200 W.
The accuracy of maintaining the temperature in large rooms is ± 1˚С.

A more complex and expensive design is the XM-18 universal controller. The device is produced in the PRC, and in russian market comes in two versions - with an English and a Chinese interface. The export option for Western Europe is naturally preferable when choosing.

Mastering the device will not take much time. Depending on what temperature should be in the incubator, you can adjust the factory program using 4 keys. On 4 screens of the front panel, the current values \u200b\u200bof temperature, humidity and additional operating parameters are displayed. Active modes are indicated by 7 LEDs. Sound and light alarm in case of dangerous deviations greatly facilitates control. Device capabilities:

The working temperature range is 0-40.5˚С with an accuracy of ± 0.1˚С.
Humidity control 0-99% with an accuracy of ± 5%.
The maximum load on the heater channel is 1760 W.
Maximum load on channels of humidity, motors and alarm no more than 220 W.
Egg turning interval 0-999 min.
Cooling fan operating time 0-999 sec. with an interval between periods 0-999 min.
Permissible room temperature -10 to + 60 +С, relative humidity no more than 85%.

When choosing thermostats with an air temperature sensor for an incubator, consider the capabilities of your design. A small incubator with a head will have enough temperature and humidity control, and most additional options expensive equipment will remain unclaimed.

Thermostat - do it yourself

Despite the large selection of finished products, many people prefer to assemble a thermostat circuit for an incubator with their own hands. The simplest optionpresented below was one of the most massive amateur radio designs in the 80s. Simple assembly and affordable element base outweighed the drawbacks - dependence on room temperature and instability to network interference.

Amateur radio circuits based on operational amplifiers often outperformed their industrial counterparts in performance. One of such schemes, assembled on the KR140UD6 OS, can be repeated even by beginners. All details are found in household radio equipment at the end of the last century. With serviceable elements, the circuit starts working immediately and only needs calibration. If you wish, you can find similar solutions on other op amps.

Now more and more circuits are made on PIC-controllers - programmable microcircuits, the functions of which are changed by firmware. The thermostats made on them are distinguished by simple circuitry, in terms of functionality they are not inferior to the best industrial designs. The diagram below is for illustration purposes only, as it requires the corresponding firmware. If you have a programmer, it is easy to download ready-made solutions along with the firmware code on the amateur radio forums.

The speed of the regulator's response directly depends on the mass of the temperature sensor, because an overly massive body has a lot of inertia. You can “coarse” the sensitivity of a miniature thermistor or diode by putting on a piece of plastic cambric. Sometimes it is filled with epoxy for tightness. For single-row, top-heated designs, it is best to place the sensor directly above the surface of the eggs at an equal distance from the heating elements.

Incubation is not only profitable, but also exciting. Combined with technical creativity, for many it becomes a lifelong hobby. Do not be afraid to experiment and we wish you successful implementation of your projects!

An overview of thermostats for an incubator - video

The temperature regulator inside, regardless of how the device is made, independently or factory made, belongs to one of the most important elements of this product.

Nature stipulates that suitable conditions are needed to breed young birds of different breeds. For example, the temperature is different from the parameters for breeding ducks. at a temperature of 37.7 °, goose needs 38.8 °.

It is impractical to build incubators separately for each breed of birds, therefore, they provide for the regulation and maintenance of the necessary conditions using thermostats. If you decide to create a homemade incubator thermostat, take it seriously.

To carry out such work is within the power of those who have mastered the basics of radio electronics, know how to handle not only a soldering iron, but also measuring instruments. In addition, manufacturing skills will come in handy. printed circuit boards, assembly and tuning of radio electronic devices.

In this article we will try to talk about how you can make and adjust the temperature regulator for incubating eggs yourself.

Regulator circuit selection

If you take factory products as a basis for the manufacture of a thermostat, you may encounter insurmountable difficulties in assembly, and especially in setting up such products.

To get around unnecessary problems, it is best to choose a product scheme available for making at home.

Important: carefully study the description of the design of the selected device, especially its element base... A circuit simple in appearance may contain scarce radio components.

The main criterion for any type of thermostat is to ensure high sensitivity to changes in the internal temperature inside, as well as an instant response to these changes. "DIYers" in most cases use two options for constructing regulators:

Building a device based on electrical circuit and radio components. The method is complex and accessible for trained specialists;
Manufacturing a regulator based on a thermostat from household appliances.

Let's take a quick look at both manufacturing options.

Manufacturing of a thermostat based on a circuit and radio components

The figure below shows a schematic diagram of a homemade incubation temperature controller.

If you carefully consider the circuit of this device, you can make sure that its assembly requires widespread radio components.

Attention: all elements are powered by a 220 volt network, therefore, strict adherence to safety rules when working with electrical appliances is required.

For self-manufacturing of the device, you will need to purchase the following radio parts:

Zener diode of any type that can provide voltage stabilization within 7-9 Volts;
Two transistors, one of them from MP 42 with any letter or similar to it, the second from the KT 315 series, the letter index of the device can be any;
Thyristor from the KU 201-KU 202 series, the letter in the designation must be H;
Four diodes of the KD 202 series, preferably with the letter designations H or HC. You can use other semiconductor devices, provided that their permissible power is at least 600 W;
The mode is regulated by a variable resistor of any type with a resistance from 30 to 50 kOhm;
Resistor R5 must have a power dissipation of at least 2W, the rest 0.5W each;
You also need to purchase an MKU type relay (multi-contact unified).

In the diagram shown in figure, the temperature sensor is transistor VT1, which is placed in a glass tube and laid directly on the tray with eggs. When the regulator is plugged in, works relay, its contacts open and the incubator is heated by lamps that are connected to the network 220 volt.

When disconnected from the network, relay contacts close and connect to work battery and car heating lamps. When resuming supply voltage, the relay is activated again and connects with the second pair of contacts charger device for recharging the battery. The variable resistor is set threshold required temperature. Special requirements to charger no, you can use any available.

Thermostat as a regulator

This option is easier to manufacture and at the same time very reliable in operation. To make it, you will need to find any thermostat from household appliances, for example, from an iron.

He needs to be prepared for work in a certain way. For this any in an accessible way fill the thermostat housing with ether and seal well.

It is important to know: ether is a strong volatile substance, so you need to work with it quickly and accurately.

Ether is very sensitive to the slightest change in the outside temperature, which leads to a change in the state of the thermostat housing. The screw, which is soldered to the case, is firmly connected to the pins. At the right time, the heating element is turned on or off. The desired temperature is set by turning the adjusting screw (numbered 6 in the figure).

Please note that before laying eggs, you need to adjust the desired temperature and warm up the incubator.

So, as can be seen from the description, it is not difficult to make a thermostat in an incubator. Even a schoolboy who is fond of radio electronics can do this. The circuit does not contain scarce radio components. The elements are mounted on a printed circuit board or mounted on a surface mount.

If an "electric brood hen" is independently made, it is useful to provide for an increase in the percentage of hatching young birds.
From this video you will learn how to make a thermostat for an incubator with your own hands:

Among the numerous assortment of useful devices that bring comfort to our life, there are a large number of those that you can do yourself. This number includes a thermostat, which turns on or off heating and cooling equipment in accordance with a certain temperature at which it is set. Such a device is perfect for cold weather, for example, for a basement where you need to store vegetables. So how to make a thermostat with your own hands, and what parts will be needed for this?

Diy thermostat: diagram

About the design of the thermostat, we can say that it is not particularly difficult, it is for this reason that most radio amateurs begin their training with this device, and it is also on it that they hone their skills and craftsmanship. You can find a very large number of device circuits, but the most common is a circuit using the so-called comparator.

This element has several inputs and outputs:

One input corresponds to the supply of a reference voltage, which corresponds to the required temperature;
The second receives voltage from a temperature sensor.

The comparator itself takes all incoming readings and compares them. If it generates a signal at the output, it will turn on the relay, which will supply current to the heating or refrigeration device.

What parts are needed: do-it-yourself thermostat

For a temperature sensor, a thermistor is most often used, this is an element that regulates the electrical resistance depending on the temperature indicator.

Semiconductor parts are also often used:

Diodes;
Transistors.

Temperature should have the same effect on their characteristics. That is, during heating, the transistor current should increase and at the same time it should stop working, despite the incoming signal. It should be noted that such details have a big drawback. It is too difficult to calibrate, more precisely, it will be difficult to tie these parts to some temperature sensors.

However, at the moment the industry is not standing still, and you can see devices from the 300 series, this is the LM335, which is increasingly recommended by experts and the LM358n. Despite the very low cost, this part takes the first position in the markings and focuses on the combination with household appliances... It is worth mentioning that modifications of this part LM 235 and 135 are successfully used in the military and industrial sectors. Including about 16 transistors in its design, the sensor is able to work as a stabilizer, and its voltage will completely depend on the temperature indicator.

The addiction is as follows:

For each degree there will be about 0.01 V, if you focus on Celsius, then for an indicator of 273 the result at the output will be 2.33V.
The range of work is limited in the indicator from -40 to +100 degrees. Thanks to such indicators, the user completely gets rid of the regulation by trial and error, and the required temperature will be provided in any case.

Also, in addition to the temperature sensor, you will need a comparator, it is best to purchase an LM 311, which is produced by the same manufacturer, a potentiometer in order to form a reference voltage and an output setting to turn on the relay. Don't forget to purchase a power supply and dedicated indicators.

DIY temperature controller: power and load

As for the connection of the LM 335, it must be serial. All resistances must be selected so that the total value of the current that passes through the temperature sensor corresponds to values \u200b\u200bfrom 0.45 mA to 5 mA. Exceeding the mark must not be allowed, as the sensor will overheat and display distorted data.

The thermostat can be powered in several ways:

Using a 12 V-rated power supply;
Using any other device, the power supply of which does not exceed the above indicator, but the current flowing through the coil must not exceed 100 mA.

Once again, we recall that the current indicator in the sensor circuit should not exceed 5 mA, for this reason, you will have to use a high-power transistor. KT 814 is best suited. Of course, if you want to avoid using a transistor, you can use a relay with a lower current level. It will be able to work from a voltage of 220 V.

Homemade thermostat: step by step instructions

If you have purchased all the necessary components for the assembly, it remains to consider detailed instructions... We will consider it using the example of a temperature sensor designed for 12V.

A homemade temperature controller is assembled according to the following principle:

We prepare the body. You can use old shells from the counter, for example, from the Granit-1 installation.
You choose the scheme that you like best, but you can also orient yourself on the board from the counter. A forward stroke marked "+" is required to connect a potentiometer, an inversion input marked "-" will serve to connect a temperature sensor. If it so happens that the voltage at the direct input is higher than the required one, a high mark will be set at the output and the transistor will start supplying power to the relay, and this, in turn, to the heating element. As soon as the output voltage exceeds the permissible level, the relay will turn off.
In order for the thermostat to work on time and the temperature differences are ensured, it will be necessary to make a negative-type connection with a resistor, which is formed between the direct input and output on the comparator.
As for the transformer and its power supply, then an induction coil from an old electric meter may be needed. In order for the voltage to correspond to the indicator of 12 volts, you will need to make 540 turns. It will be possible to fit them only if the wire diameter is no more than 0.4 mm.

That's all. In these small actions, all the work on creating a thermostat with your own hands consists. Perhaps you won't be able to do it right away without certain skills, however, based on photo and video instructions, you can test all your skills.

Thanks to its simple design, a self-created thermocontroller can be used anywhere.

For instance:

For underfloor heating;
For the cellar;
Can deal with air temperature regulation;
For the oven;
For an aquarium, where it will control the temperature of the water;
In order to control the temperature value of the electric boiler pump (turning it on and off);
And even for a car.

It is not necessary to use a digital, electronic or mechanical commercially available thermal switch. Having bought an inexpensive thermostat, adjust the power on the triac and thermocouple and your homemade device will work no worse than the purchased one.

How to make a thermostat with your own hands (video)

In our article dedicated to the self-creation of a thermostat, all the main points were indicated, from the necessary details for the design to step by step instructions... Do not rush to immediately start creating, study the literature and advice from experienced craftsmen. Only with the right approach you can get perfect results on the first try.

Since the soldering process is associated with the melting of the solder, it is necessary to always maintain the optimum heating temperature. The following factors are taken into account:

Solder melting temperature (from 150 to 320 degrees);
Heat resistance of the elements on which the soldering is performed. Many radio components simply fail with prolonged heating, and wire insulation loses its properties;
Contact dissipation area. When connecting massive elements, it is necessary to have a margin of temperature and power.

If you are just soldering wires, it is enough to know the power of the soldering iron and the approximate melting point of the solder. The criterion is simple - fast or slow heating.

But when installing printed circuit boards or repairing electrical appliances, the incorrectly selected temperature of the soldering iron can result in the purchase of expensive radio components that will be damaged high temperature.

Soldering iron temperature - how to choose

If the installation is not associated with specific radio parts that are sensitive to overheating, the degree of heating of the tip should be 10 degrees higher than the melting temperature of the solder. And not the point of the beginning of the melt - namely, the temperature of a stable being in a liquid state;
If you plan to connect contacts with a large area and mass, it is not the amount of heating that increases, but the power of the soldering iron. A low-power device with a high temperature will still not cope with dissipation. Compensate for the weight of the part with the appropriate size of the working tip. And to heat it up, power is required, not degrees;
The passport of radio components usually indicates the maximum allowable heating value of the case. This also applies to the soldering temperature. Again, opt for power over power boost. We must try to keep the contact time of the sting and the part to a minimum. The solder should melt and the body should not be overheated.

For different conditions work produced electric soldering irons with temperature control.

The design does not matter, the regulator can be built into the housing or made as a separate unit. The main thing is that you know how hot the tip of the tool is.

Among the various useful gizmos that can add comfort to our lives, there are many that you can easily do yourself.

This category also includes a thermostat, also called a thermostat, a device that turns on and off heating or refrigeration equipment in accordance with the temperature of the environment in which it is installed.

Such a device can, for example, turn on a heater in the basement where vegetables are stored during extreme cold weather. From our article, you will learn how you can make a thermostat with your own hands (for a heating boiler, refrigerator and other systems) and what parts are best for this.

The device of the thermostat is not particularly complicated, therefore many novice radio amateurs hone their skills in the manufacture of this device. Circuits are offered in a variety of ways, but the most widespread is the option using a special microcircuit called a comparator.

This element has two entrances and one exit. A certain reference voltage is supplied to one input, which corresponds to the required temperature, and to the second, the voltage from the temperature sensor.

Thermoregulator circuit for warm floors

The comparator compares the incoming data and, at a certain ratio, generates a signal at the output that turns on the transistor or turns on the relay. This supplies current to the heater or refrigeration unit.

Diy temperature controller device details

The temperature sensor is usually a thermistor - an element whose electrical resistance changes with temperature. Semiconductor elements are also used - transistors and diodes, the characteristics of which are also influenced by the temperature: when heated, the collector current increases (for transistors), while a shift in the operating point is observed and the transistor stops working without responding to the input signal.

But such sensors have a significant drawback: they are quite difficult to calibrate, that is, "tie" to certain temperature values, which is why the accuracy of a homemade thermostat leaves much to be desired.

Meanwhile, the industry has long mastered the production of inexpensive temperature sensors, which are calibrated during the manufacturing process.

This includes a device of the LM335 brand from National Semiconductor, which we recommend using. The cost of this analog temperature sensor is only $ 1.

"Three" in the first position of the digital row in the marking means that the device is intended for use in household appliances. Modifications LM235 and LM135 are intended for use in industry and military, respectively.

With 16 transistors, this sensor works like a Zener diode. Moreover, its stabilization voltage depends on the temperature.

The dependence is as follows: for each degree on the absolute scale (Kelvin) there is 0.01 V voltage, that is, at zero Celsius (273 Kelvin), the stabilization voltage at the output will be 2.73 V. The manufacturer calibrates the sensor at a temperature of 25C (298K ). The working range is from -40 to +100 degrees Celsius.

Thus, assembling a thermostat based on LM335, the user gets rid of the need to select by trial and error the reference voltage at which the device will provide the required temperature.

V \u003d (273 + T) x 0.01,

Where T is the temperature of interest to the user on the Celsius scale.

In addition to the temperature sensor, we need a comparator (the LM311 brand from the same manufacturer is suitable), a potentiometer for generating a reference voltage (setting the required temperature), output device to connect the load (relay), indicators and power supply.

The thermostat is an integral part of autonomous heating. will help keep the temperature in the house at a comfortable level.

Let's analyze the principle of operation of the thermostat for an infrared heater.

Should you install a thermostat for a heating radiator? In this article, we will consider the purpose of the device and the types and features of installation.

Thermostat power supply

Temperature sensor LM335 is connected in series with resistor R1. So, the resistance of this resistor and the supply voltage must be selected in such a way that the value of the current flowing through the thermal sensor is in the range from 0.45 to 5 mA.

Do not exceed the maximum value of this range, as the sensor characteristics will be distorted due to overheating.

You can power the thermostat from standard block 12 V supply or from a self-made transformer.

Turning on the load

As an actuator supplying power to the heater, you can use automotive relay... It is designed for a voltage of 12 V, while a current of 100 mA must flow through the coil.

Recall that the current in the thermal sensor circuit does not exceed 5 mA, therefore, to connect the relay, you need to use a transistor with a higher power, for example, KT814.

You can use a relay with a lower turn-on current, such as SRA-12VDC-L or SRD-12VDC-SL-C - then the transistor is not needed.

How to make a thermostat with your own hands: step by step instructions

Consider how thermostats (thermostats) are made with a do-it-yourself 12 V air temperature sensor.The device is assembled in the following sequence:

First of all, you need to prepare the body. A used counter, for example, "Granit-1", will do.
The circuit can be assembled on a board from the same counter. A potentiometer is connected to the direct input of the comparator (marked with a "+" sign), which allows setting the temperature. To the inverse input ("-" sign) - LM335 temperature sensor. If the voltage at the direct input turns out to be higher than at the inverse, the comparator output will set high level (unit) and the transistor will supply power to the relay, and it will supply power to the heater. As soon as the voltage at the inverse input turns out to be greater than at the direct one, the level at the output of the comparator will go low (zero) and the relay will turn off.
To ensure the temperature difference, that is, the thermostat is triggered, for example, at 23 degrees, and the shutdown is at 25, it is necessary to create a negative feedback between the output and the direct input of the comparator.
The transformer for powering the thermostat can be made from a coil from an old induction-type electric meter. There is space for a secondary winding on it. To get a voltage of 12 V, you need to wind 540 turns. They can fit if you use a wire with a diameter of 0.4 mm.

Simple homemade thermostat

It is convenient to use the meter terminal block to turn on the heater.

What should be the heater?

The power of the heater depends on how much current the contacts of the relay used can withstand. If this value is, for example, 30 A (a car relay is designed for such a current), then the heater can have a power of up to 30 x 220 \u003d 6.6 kW. You just need to first make sure that the wiring and the machine in the dashboard are capable of withstanding such a load.

Mounting

Let's consider how the device should be installed correctly.

The thermostat should be installed in the lower part of the room, where cold air accumulates.

However, it is important to prevent the effects of thermal noise, which could confuse the instrument.

So, for example, you should not place the thermostat in a draft or near electrical equipment that emits heat.

Setting the thermostat

As already mentioned, the thermostat based on the LM335 sensor does not need to be adjusted. It is enough to know the voltage supplied by the potentiometer to the direct input of the comparator.

You can measure it with a voltmeter. The required voltage value is determined using the above formula.

If you need, for example, for the device to work at a temperature of 20 degrees, it should be 2.93 V.

If any other element is used as a temperature sensor, the reference voltage will have to be checked empirically. To do this, you need to use a digital thermometer, for example, TM-902S. For accurate adjustment, the sensors of the thermometer and thermostat can be connected with electrical tape, after which they are placed in an environment with different temperatures.

Thermostat from scrap materials

The potentiometer knob must be rotated smoothly until the thermostat works. At this moment, you should look at the scale of the digital thermometer and put the temperature displayed on it on the scale of the thermostat. You can define extreme points, for example, for temperatures of 8 and 40 degrees, and mark intermediate values \u200b\u200bby dividing the range into equal parts.

If a digital thermometer is not at hand, the extreme points can be determined by water with ice floating in it (0 degrees) or by boiling water (100 degrees).