Incubator thermostat

Before installing the device, it is better to get acquainted with the principle of its operation. The Russian market offers an impressive number of models from different companies. Almost all of them operate according to the same scheme, regardless of their purpose.

According to this plan, devices for maintaining the atmosphere in an aquarium, an incubator, a floor, etc. are manufactured. It allows maintaining the thermal regime with an accuracy of ± 0.5 ° C.

The device includes a bellows for the liquid composition, a spool, a rod and an adjustable valve.

simple thermostat circuit thermostat for incubator

Assembly instructions

Required materials, parts and tools:

• magnifier
• pliers,
• soldering iron
• insulating tape
• several screwdrivers
• copper wires
• semiconductors
• standard red LEDs
• pay,
• textolite forged,
• lamps,
• stabilitron,
• thermistor,
• thyristor.
• display and an internal type generator with a capacity of 4Mgu (for creating digital devices on the microconstroller),

Step-by-step instruction:

1. First of all, you need an appropriate chip, for example, K561LA7, CD4011
2. Fee need to prepare for the laying of paths.
3. To similar schemes Thermistors with a power of 1 kOm to 15 kOm are not bad, and it must be located inside the object itself.
4. Heating device must be included in the resistor circuit, due to the fact that the power change, which is directly dependent on lowering degrees, affects the transistors.
5. Afterwardssuch a mechanism will warm the system until the moment when the power inside the thermal sensor returns to its original value.
6. Sensors of the regulator of the similar plan need customization. During significant drops in the surrounding atmosphere, it is necessary to control the heating inside the object.

Build a digital device:

1. Microcontroller should be connected together with a temperature sensor. It must have port outlets, which are necessary for installing standard LEDs that work in conjunction with a generator.
2. After connecting the device to the network With a voltage of 220V, the LEDs will automatically turn on. This will be an indication that the device is in working condition.
3. The design of the microcontroller is memory. If the device settings are lost, the memory automatically returns them to the initially agreed parameters.

Instead of the designated chip K140UD6 you can use K140UD7, K140UD8, K140UD12, K153UD2. In the role of the Zener diode VD1, you can implement any tool with a stabilization power of 11 ... 13 V.

In the case when the heater exceeds the voltage of 100 W, then the VD3-VD6 diodes must be superior in power (for example, KD246 or their analogues, with a reverse power of at least 400V), while the trinistor should be mounted on small radiators.

The value of FU1 should also be made larger. The control of the device is reduced to the selection of resistors R2, R6 in order to safely close and open the trinistor.

Device

The temperature always remains at the same level due to the switching on and off of the heating device (heating element). A similar principle of control is used on all plain structures.

It may seem that the scheme of the thermostat is very simple, but as soon as it comes to collecting the device, there are a lot of questions related to the technical part.

The thermostat device includes:

1. Temperature sensor - created on the basis of the comparator DD1.
2. The key scheme of the thermostat is a comparator DA1, manufactured on an operational amplifier.
3. The desired temperature indicator exposed by a resistor R2, which is connected to the inverting input 2 of the board DA1.
4. In the role of a thermal sensor There is a thermistor R5 (type MMT-4) connected to the input of the 3rd device.
5. Construction scheme does not have a galvanic isolation with the network, and takes energy from the parametric stabilizer on the parts R10, VD1.
6. In the role of the power supply for the device You can get a cheap network adapter. During its connection, you must follow the rules and requirements for new wiring, as the conditions of the room may be electro-hazardous.

The insignificant reserve of the C1 capacitor contributes to a gradual increase in power, which leads to a smooth (no more than 2 seconds) switching on of electric lamps.

Self-Costs

Today, any such gadget can be purchased in the store. The price range is quite large, and the cost of many models is more than 1000 rubles. In terms of financial investments, this is quite unprofitable, so it’s much cheaper to do it yourself.

Costs for self-assembly are several times lower, namely:

• fee K561LA7 will cost no more than 50 rubles,
• a thermistor with a capacity of 1 kOm up to 15 kOm is about 5 rubles,
• LED (2 pieces) - 10 rubles.,
• stabilitron - 50 rubles,
• thyristor - 20 rubles,
• display - 200 rubles (for creating digital devices on a microconstroller),

Device Overview

The peculiarity of the thermostat for such a device as an incubator is that it allows you to adjust the temperature and humidity, as it is paired with special sensors and heating elements. Equipment of this type is capable of tracking environmental drops and compensating for them.

What is a

Any model of a temperature regulator gathers from the following elements:

• Thermometer - it is able to display the ambient temperature, transmitting information to the main control unit. In some cases, temperature sensors are embedded in the main unit,
• The main unit (depending on the type of device) is necessary to set certain parameters and supply voltage, which is subsequently output to the heating elements,
• Heating devices - this device is necessary in order to transform electricity. As an economical device used incandescent lamps, which are easily adjustable and characterized by durability. If it is a question of more expensive models, in them heating tena are established.

Note! Hatching eggs with an incubator is a difficult and lengthy process where even a small mistake can become critical.

What types of thermostats are

At the moment, there are several types of thermostat for sale, where everyone works efficiently. But between them there is a definite difference to which attention should be paid.

So, the devices are of the following types:

• Digital - reliable, resistant and with accurate measuring readings devices. Differ in higher cost, but at the same time have considerable functionality, in comparison with simpler models,
• Mechanical - optimal, if you want to maintain only one temperature. To exercise precise control, an additional thermometer is installed,
• Analog - a classic electronic thermostat that has the usual functionality.

Important! If the choice fell on the digital and analog models, then it should be taken into account how high-quality electricity is in the area where the thermostat will be installed. After all, if the device will have to deal with frequent surges of electricity, it simply fails faster.

How does the equipment work?

The principle of operation of the device depends on its design. In electric models, the selected temperature for the incubator is maintained: if it drops, the heating elements start working, if they rise above the set limit, they are turned off.

The main element of the electric model of the thermostat is a plate of bimetal, which provides for the change of its own physical properties depending on temperature. By contacting with the heating medium or element, the plate is able to control the heater. If the device has a lower temperature, the plate is deformed, as a result of which the electrical contacts are closed, and the electric current flows to the heating element.

As soon as the required temperature condition is reached, the plate is bent in the opposite direction, after which the contact is broken and the device is disconnected from the power supply. If we consider mechanical temperature controllers, then in them some substances have specific qualities. For example, if the temperature rises, they increase in volume, if they decrease, they decrease. The thermostat in working condition causes a constant change of these processes. In modern devices, particularly fine tuning is available so that the thermostat reacts to even the smallest change in temperature.

Interesting. For the first time, incubators appeared in ancient Egypt, for the equipment of which barrels, furnaces and insulated rooms were suitable. In those days, it was the responsibility of the priests, who used a special liquid to control the microclimate (it hardened when a certain temperature was reached).

Choosing a thermostat, you need to know what features you should pay attention to. It:

• Resistance to voltage drops and environmental changes,
• A person must take minimal part in planting,
• Visually, you can notice the features of the climate in the incubator,
• The heating elements must turn on and off automatically,
• It will not need to constantly adjust and control.

Features of the thermostat assembly do-it-yourself

Thanks to modern science, equipment is now available that can detect temperatures up to 0.1 degrees Celsius. This accuracy is available to digital thermostats, and as for the other types, they are less accurate. The main part of this device is the heating element.

First of all, a certain temperature is established, and if it rises above the established norm, a special sensor will work. A similar principle applies if the temperature drops. Then the thermal sensor is activated, and the air begins to warm up again. Equally important is the environment - the place where the incubator is located.

Installation requires a constant flow of fresh air. As for room temperature, it should not be above +25 degrees Celsius. If there are sun rays on the temperature controller, it is likely that it will display erroneous readings, so it is better to install the incubator away from the sun.

The most important early days of laying eggs. At this time, it is necessary to monitor the temperature in the incubator very accurately. If the egg overheats a little, it will critically affect the embryo. If, however, it is correct to observe the temperature, use high-quality eggs and adhere to the normal development of the embryo, then he himself subsequently adjusts to the temperature regime, as a result of which healthy and strong chicks will hatch.

For the most part, the birth of chicks depends on temperature, so the thermostat acts as the main element.

Create a homemade thermostat - a rather complicated and painstaking work. It must be properly and accurately configured, only depends on it, whether the young or will not. If you make the device yourself, then the most difficult element of it is the automatic thermostat, for which you need to build on a certain circuit.

You can buy the device separately, where all the rules were taken into account for the assembly of the regulator, and a high-tech and precise scheme was applied. In conditions at home, it is very difficult to copy a complex technical apparatus, and a lot of special skills and knowledge are required. In any case, if you want to make the thermostat yourself, it is immediately recommended to build on your own skills, since working with devices is not as easy as it seems at first glance.

A key requirement is placed on homemade regulators: they must accurately respond to temperature changes in the incubator. It is important to understand that it depends on this, whether there will be future offspring or not.

At the moment, there are two ways to assemble a thermostat with your own hands:

• Electrotechnical,
• The thermostat is applied.

As for the first, electrical, it is quite complicated, since it requires special knowledge and skills. It uses electrical circuits and special devices for the manufacture of the regulator. At a minimum, knowledge of electrical engineering will be useful, which will help to create an accurate and reliable instrument. If the necessary knowledge is not available, then the second method, more simple, will do.

The way with the thermostat is as follows:

• To make an automatic thermostat, you need an ordinary thermostat. If it is not possible to find it separately, then it is easy to get from old household appliances, for example, from an iron. This method is also reliable, but at the same time many times simpler.
• Make the thermostat inoperative. For this, it is decoupled or riveted and washed in the middle,
• It should be filled with ether, a feature of which is increased volatile properties. After filling, the thermostat should be soldered, with the result that the device comes out sensitively reacting to the surrounding temperature. Capacity will narrow and expand on temperature. This is a feature of the physical properties of the ether itself,
• Using screws, you need to attach special plates to the finished thermostat. Due to the temperature change, the thermostat will begin to act on the contacts,
• The next step is the operation of the electric circuit: when it is closed, heating is activated, which acts in the reverse order. The principle of operation is very simple: thanks to the mechanical actions in the incubator, the optimum temperature is maintained.

Note! Before using a self-assembled regulator, it should be carefully configured. The main thing - to create the desired distance between the contacts, in the end you get the maximum sensitivity.

Growing birds is a profitable business, but you need to know what equipment to use and how to use it. The key element in any incubator for hatching eggs is the thermostat, which is both mechanical and digital, where the latter is characterized by greater accuracy of indicators, and, therefore, more reliable. If desired, this element is assembled by hand, but for this you need to have certain knowledge and experience.

Overview of thermostats on the market

Among the most popular models today are E 51.716 and IWarm 710. Their non-flammable, plastic-made case has small dimensions, but a large number of useful tasks and an integrated battery. It has a fairly large built-in display, which displays the corresponding temperature characteristics.

The cost of these models is presented in the range of 2,700 thousand rubles.

The special features of E 51.716 include the fact that it has a cable of 3 m in length, capable of balancing the temperature simultaneously from the floor itself, and that the device can be embedded in a wall in any position.

The only thing you should think about before installing it, how exactly it will be located, so that the switch buttons do not close with foreign objects, and are easily accessible.

The disadvantages of the thermostat include a minor set of functions.However, similar devices perform them quite easily. In operation, this can cause discomfort. Also, in the memory of E 51.716 and IWarm 710 there is no automatic heating function, so you have to do it yourself.

Electronic regulators with the mechanical principle of work:

1. Work regulation based on automation, and carried out using the buttons located on the panel.
2. Include display, which denotes the former and given degrees.
3. It is possible to customize the device yourself: number, operation time, heating cycle with preservation of a specific mode, it is also possible to indicate the degree of heating.
4. In comparison with mechanical analogs, the temperature of electrical models is easily adjustable to approximately 0.5 values.

To purchase such a model will take no more than 4 thousand.

Electronic configuration:

1. Independently control the temperature.
2. Just one device can control the atmosphere for several days ahead and separately for each room.
3. Allow to set the mode "absence", and do not spend extra money on it if no one is at home.
4. The system automatically analyzes the quality of work. devices in every room. The owner will not have to guess about possible malfunctions in the work, as the system will give all the shortcomings on its own.
5. Manufacturers of expensive models provided the ability to control modes, being away from home. Adjustment is carried out using the built-in Wi-Fi router.

The cost of such devices depends on a set of built-in functions, therefore, varies from 6,000 to 10,000 thousand rubles and above.

Purpose and principle of operation of the thermostat

The thermostat, sometimes called a thermostat (which is not quite true, the entire incubator can be called the entire incubator), is used to maintain the set temperature by turning the heater on and off depending on the set temperature. Temperature is determined using a sensor.

С помощью терморегулятора фермеры поддерживают нужную температуру в инкубаторе.

Датчиком может быть:

• биметаллическое термореле,
• термопара,
• термометр сопротивления,
• термистор,
• полупроводниковый датчик.

Как пример, можно привести датчик американской фирмы Dallas Semiconductor, имеющий однопроводной цифровой интерфейс. Его можно использовать в схеме на микроконтроллере. The scheme is simple, the details are inexpensive, but it requires a lot of programming skills and knowledge, practically professional, to make it all work reliably and reliably. After all, a party of hundreds of eggs may depend on it.

When the sensor temperature exceeds a predetermined value, the power supply circuit of the heater, for example, incandescent lamps, is turned off and the incubator starts to cool down. When the temperature falls below another setpoint, the lights turn on again.

It turns out the circuit breaker with feedback on temperature. Even with two: the negative feedback turns the machine off, and the positive one turns it on. The gap between the on and off thresholds is called hysteresis. If this hysteresis is zero (which in practice does not happen), or is very close to it, then the regulator will turn on and off too often and something, rather soon, will fail.

Thermostat for incubator can be done independently.

There are simple regulators in which the hysteresis is not standardized and has a value sufficient for practice. But there are those where the switching threshold and hysteresis are set separately and very accurately. They are used in industry and research.

What is better: buy or make yourself

Temperature controllers on sale that are suitable for use in incubators are on the market, their price ranges from several hundred to several thousand rubles. If you search well, you can find a very suitable option. How well they work, you can read on the forums of poultry farmers and farmers.

Independent production is also quite affordable, and this is the budget option. All necessary parts can be purchased at online stores with postal delivery. For those who like to do everything on their own, and such people are worthy of all respect if they are serious about the matter, the rest of the article is intended.

How to make the thermostat yourself

A hand-made device made with one's own hands can in no way yield to an industrial one in its accuracy and stability, well, except that its ergonomics will be a little worse. But for those who breed birds, this is not primarily of concern.

Temperature controllers, manufactured independently, are not inferior to those that are on sale.

Self-made device is made from the same industrial parts, and it is not clear why it should be worse? Unfortunately, in Russia such an opinion is not uncommon: if self-made means bad, but if it’s factory-made, then for the sake of it you can even get a loan head-to-head. You will see that this is not the case at all.

Homemade electronic thermostat

His diagram is shown below. There are few details in it, they are inexpensive, and it is not difficult to get them.

Details can be bought in the chipdip.ru store. This is not an advertisement, ChipDip has not needed any advertising for a long time. It is a little about the prices: zener diodes 1N4742A, 1N4736A stand there 2 rubles apiece. A similar Russian Zener diode, especially in a metal case, can cost under a hundred. Operational amplifier LM328N costs about 30 rubles, 1N4004 rectifier diodes cost three rubles apiece.

The field-effect transistor IRF730PBF costs about 30 rubles. Two 1N5406 diodes cost 10 rubles together. If instead of them to use the Soviet diode in a metal case at 10A, then it can cost hundreds of rubles because of the precious metals inside. In general, it is necessary to understand the element base in order not to overpay many times.

The photo shows a diagram of a homemade thermostat for an incubator.

How this scheme works. Resistor R8 and capacitor C2 limit the current supplying the rectifier diodes VD2 and VD3. The voltage is stabilized by the Zener diode VD1 and filtered by the capacitor C1. This is 12 volts to power the comparator circuit assembled on the DA1 operational amplifier. The LM358 chip contains two op amps of which one is used.

The power part of the circuit is formed by a fuse F1, lamps L1 ... Ln connected in parallel, a diode VD4 and a field-effect transistor channel VT1. Since this circuit only transmits current in one direction, the lamps will work fully. However, this will only increase the reliability and service life. We will return to the issue of lamps, but for now about the operation of the regulator.

At the input of the OU there is a bridge on the resistors R1-R5. The signal is formed on the resistors R1 and R2 (R2 is a thermistor). It is compared with the voltage on the engine variable resistor R4. The hysteresis is provided to the comparator by resistor R6 (together with resistor R2). The op amp boosts the signal difference between the input “minus” (inverting input) and “plus” (direct input).

Thermistor R2 with increasing temperature reduces its resistance. First, the output of the shelter voltage is close to 12V. The field-effect transistor VT1 is open and the lamps are turned on.

The photo shows the thermistors MMT-1 and MMT-4.

As soon as the difference between the reference voltage and the input signal becomes negative, at the output of the amplifier the voltage abruptly drops to almost 0V. The transistor closes and the lights go out. Resistor R6 limits the output current of the op-amp through the Zener diode, and the Zener diode limits the voltage at the gate of the transistor to a safe value (6.8 V).

Now for the details without nominal values. Let's do a little development of electronic circuits. What will be the nominal values, depends on what we choose a thermistor.

Let's look at the generalized current-voltage characteristic of the MMT-1 thermistor (MMT-4 has a similar one).

You can get a thermistor with any rating, so it is important to be able to calculate the input part of the circuit. For example, an MMT-1 thermistor 1.5k 20% costs 14 rubles (there are thermistors and for five thousand rubles). 20% is the nominal error. This will have no effect on the accuracy of the calibrated instrument, the thermistors are very stable.

Note! It is undesirable to take thermistors with resistance less than 1 com. Otherwise, the mode of operation of the circuit will be broken and the thermostat will work unstable.

Suppose we want to regulate the temperature in the range of 34-39 degrees. The graph shows what the relative resistance should be at the thermistor for these temperatures. We calculate the working resistance of the thermistor: R2 = 1500 * 0.7 = 1050 Ohm. The resistance of R1 should also be approximately the same, so that at the point of their connection there is half the supply of 6V or so. OU is better to work in this area.

The photo shows a graph of the relative resistance of the thermistor for different temperatures.

At the same time, we calculate the voltage of the signal, assuming that R1 = 1k. At 30 ° C, the resistance of the thermistor will be 1500 * 0.8 = 1200 Ohm, and at 40 ° C - 1500 * 0.65 = 975 Ohm. In the first case, the current in half of the bridge with R1 and R2 will be 12 / (1000 + 1200) = 5.4545 mA, in the second case: 12 / (1000 + 975) = 6.0759 mA. We only need these currents to estimate the voltage of the signal.

In the first case, U = I * R = 5.4545 * 1200 = 6.5455 V, in the second case a similar calculation shows 5.9241 V. The difference will be 0.6214 V. To install the thermostat in this range, you will need to have the same reference voltage at the other OU input .

And the hysteresis will depend on the gain. If we want the regulator to maintain the temperature with an accuracy of 0.1 ° C, then we must first find out what voltage will correspond to such a change in temperature. It is not difficult to know: approximately 0.0062 V. We divide the temperature range by a step of one tenth of a degree and multiply by the voltage swing of the signal.

On the other hand, the output signal changes from 0 to 10-11 V. So, we need to get a gain: 11 / 0.0062 = 1774. Then the resistor R6 installed in the feedback circuit must be less than the resistance of the thermistor by the appropriate number of times: R6 = 1780/1090 = 1.63 ohms. That is, we divide the amplification value by the average value of the thermistor resistance in the operating range.

Making a thermostat with your own hands requires some knowledge.

Now it only remains to calculate R3, R4, and R5. Potentiometer R4 should be selected from wire variable resistors. They have a linear characteristic and there will be fewer surprises with graduations. In the selected area, the characteristic of the thermistor is also more or less close to a straight line.

Unfortunately, wire variable resistors are quite expensive. But they are the most stable and accurate. On eBay or aliexpress, you can find one for 150 rubles with delivery. In Russian stores, they are much more expensive. Sometimes you can find such a potentiometer completely free in old devices left over from the times of the USSR. Best fit is a small potentiometer for power 0.25-0.5 W with a nominal value of 220-470 Ohms. In extreme cases, you can take 2.2 kOhm.

Suppose we found a 1-ohm wire potentiometer (quite common). What should be the resistors R3 and R5? At 1k accounted for approximately 0.63 V voltage, and the total on the chain of resistors drops 12V. The current passing through the chain can be calculated according to Ohm’s law: I = U / R = 0.63 / 1000 = 0.63 mA. In order for the comparator to work in the signal range and the potentiometer scale is neither too stretched nor too compressed, the reference voltage must vary in the same range as the signal itself.

For the calculated current, we find the sum of all resistances R3, R4, R5: R = U / I = 12 / 0.00063 = 19.048 kΩ. Now let us recall the lower limit of the signal range from sensor R2. It is 5.9241 V. At the current found, we calculate the resistance of the lower resistor R5 = U / I = 5.9241 / 0.00063 = 9400 Ohm.

Now it is easy to find the upper resistor: R3 = 19.048 - 1 - 9.4 = 8.65. Such must be the resistances of R3 and R5 so that the scale of R4 falls into the necessary “window”. This is not a dogma, but it is better to choose resistors closer to these values. If the scale when adjusting is a little wider, then there is nothing wrong with that, the main thing is that it should not be already. You can use composite resistors, connecting them in series or in parallel, and checking the total resistance with a multimeter.

For the manufacture of thermostat for the incubator requires different components.

Similarly, the calculation is done for other thermistors. We don’t need to take special care of the input currents of the OU, they are very small and do not affect the operation of the bridge.

Thermostat design

Here is how to make a device. Typing suitable parts you need to prepare and configure in advance those elements that were calculated (R3 and R5), so that they are neatly soldered and they can be mounted further.

Resistor R6 can be taken either 1.6 Ohm, but these rarely come across, or be made up of several parallel ones (due to its small rating), or take a piece of 16.3 Ohm nichrome wire (measured with a multimeter) and cut off exactly one-tenth from it part. Then it is wound on a large resistor, say, 10 or 100 kΩ, so that it does not affect the total resistance and is soldered on its terminals.

Parts are mounted, as usual, on a suitable size printed circuit board. The scheme is simple; you can draw tracks either manually or in a suitable program for the development of printed circuit boards, for example, Sprint Layout. This is a simple free program for radio amateurs. Unfortunately, the size of the article does not allow to describe the details of the manufacture of printed circuit boards, but to find information on the Internet is not difficult.

The photo shows the process of manufacturing the thermostat.

Attention. The field effect transistor must be mounted on an aluminum heat sink with an area of ​​at least 100 cm2. Capacitor C2 must be used only new, better type K50-17, before use, you must ensure that it is not broken and does not leak.

A round scale with glued paper should be put on the potentiometer axis and fixed firmly. It will be applied graduation. The scale can be made mobile or not, the main thing is its sufficient size for future marking and “non-tolerance”. Finally, everything assembled is placed in a suitable enclosure. There is plenty of room for home design.

Now, as promised, about the lamps. The selected transistor has a maximum current of 5.5 A, but it is better to limit yourself to a smaller one. If you take incandescent lamps of 100 W, then when powered through a diode, their power will be halved.

Take current, for example, 4 A and determine the number of 100-watt lamps for this. The average current through the lamp will be about 0.23 A, taking into account the fact that the lamp operates for one half period. 4 / 0.23 = 17 lamps of 100 watts each. In practice, there will be fewer bulbs, since incubators are usually insulated. In addition, too much heat will lead to emissions of elevated temperature.

After assembly, you need to check how the self-assembled thermostat works.

Adjusting the thermostat

The adjustment consists in checking the performance after installation and applying divisions to the scale in the following order:

1. Graduation divisions.
2. Divisions in increments of half a degree.
3. The divisions in increments of 0.1 degrees.

One light bulb is included in the load, simply as a work indicator. The sensor is placed in a dry sand bath next to an exemplary thermometer. The bath, carefully and slowly, in order not to overheat, is heated on the hotplate switched on through LATR or another suitable power regulator.

Consider a single point calibration, for example, 35 ° C. First, it is necessary to balance the temperature of the sensor and the reference thermometer in the bath. Then, rotating the potentiometer, mark with a pencil the points on the circle of the scale, where the lamp lights up and where it goes out. The middle can be marked by dividing 35 degrees.

Similarly, divisions are made for other values. It does not hurt to make a graduation for tenths of a degree, given that, after all, the scale will not be linear. After performing the calibration, it will be possible to estimate the hysteresis. It should be in the range of 0.1 ... 0.15 g. Celsius

The device will only be reliable if all connections are soldered carefully, and the terminal clamp connections are clean and well tightened.

In the video, an expert talks about how to make a thermostat with your own hands.

In ancient times…

In the first domestic and industrial incubators of the last century, the temperature was regulated using bimetallic relays. To remove the load and eliminate the effect of contact overheating, the heaters were turned on not directly, but through powerful power relays. Such a 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 the positive aspects were negated by the low resolution and complexity of the adjustment. The temperature in the process of incubation must be reduced according to the schedule in increments of 0.5 ° C, and it is very difficult to do this with an exactly adjusting screw on the relay located inside the incubator. As a rule, the temperature remained constant throughout the "incubation" period, which led to a decrease in hatchability. Designs with an adjustment knob and a graduated scale were more convenient, but the accuracy of retention was reduced by ± 1-2˚С.

First electronic

The analog temperature controller for an incubator is somewhat more complicated. Usually, this term implies a type of control in which the level of 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. The accuracy of adjusting even simple circuits is within 0.3-0.5 -0С, and when using operational amplifiers, the accuracy increases to 0.1-0.05,0С.

For a rough installation of the required mode on the instrument case there is a jackal. The stability of the testimony depends little on the indoor temperature and the mains voltage drops. To eliminate the influence of interference, the sensor is connected with a shielded wire of the minimum required length. This category includes rarely encountered models with analog load control. The heating element in them is turned on constantly, and the temperature is regulated by a smooth change in 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 were equipped with serial incubators. The device is simple to operate and is equipped with a remote sensor with a 1 m cable, power cord and meter load wire. Technical specifications:

1. Load power at standard mains voltage from 5 to 500 watts.
2. The adjusting range is 36-41˚С with accuracy not worse than ± 0.1˚С.
3. Ambient temperature from 15 to 35 доС, permissible humidity up to 80%.
4. Non-contact triac inclusion of the load.
5. Overall dimensions of the case are 120х80х50 mm.

In numbers, always more accurate

Greater precision adjustments provide digital measuring devices. The classic digital thermostat for an incubator differs from the analog method of signal processing. The voltage removed from the sensor passes an analog-to-digital converter (ADC) and only then enters the comparison unit. Initially set in a digital form, the value of the required temperature is compared with that obtained from the sensor, and the corresponding command is sent to the control device.

This structure greatly improves the measurement accuracy, minimally dependent on ambient temperature and interference. Stability and sensitivity are usually limited by the capabilities of the sensor itself and the system capacity. The digital signal allows you to display the value of the current temperature on the LED or LCD display without complicating the circuitry. Значительная часть промышленных моделей имеет расширенный функционал, который мы рассмотрим на примере нескольких современных устройств.

Возможностей бюджетного цифрового терморегулятора Ringder THC-220 вполне достаточно для самодельного домашнего инкубатора. Регулировка температуры в пределах 16-42˚С и внешний блок розеток для подключения нагрузки позволяет использовать устройство и в межсезонье – к примеру, для управления климатом помещения.

Для ознакомления приводим краткие характеристики устройства:

1. The current temperature and humidity around the sensor are displayed on the LCD.
2. The range of the indicated temperature is from -40˚С to 100˚С, humidity 0-99%.
3. The selected modes are displayed on the screen as symbols.
4. The temperature setting step is 0.1 ° C.
5. Ability to adjust humidity up to 99%.
6. 24 hour day / night timer format.
7. Load capacity of one channel 1200 watts.
8. Accuracy of temperature maintenance in large rooms is ± 1˚С.

A more complex and expensive design is a universal controller XM-18. The device is produced on the territory of the People's Republic of China, and comes to the Russian market in two versions - with English and Chinese interfaces. The export option for Western Europe is naturally preferable when choosing.

Mastering the device does not take much time. Depending on what temperature should be in the incubator, you can adjust the factory program with the help of 4 keys. On 4 screens of the front panel displays the current values ​​of temperature, humidity and additional operating parameters. Indication of active modes is carried out by 7 LEDs. Audible and visual alarms for dangerous deviations greatly facilitate monitoring. Device features:

1. The working temperature range is 0-40.5 ° C with an accuracy of ± 0.1 ° C.
2. Humidity adjustment 0-99% with an accuracy of ± 5%.
3. The maximum load on the channel heater 1760 watts.
4. The maximum load on the channels of humidity, motors and alarm no more than 220 watts.
5. The interval between turning eggs 0-999 minutes.
6. Cooling fan running time 0-999 sec. with an interval between periods of 0-999 minutes.
7. Allowable room temperature -10 to + 60˚С, relative humidity not more than 85%.

When choosing thermostats with an air temperature sensor for an incubator, consider the possibilities of your design. A small incubator with its head will be enough control of temperature and humidity, and most of the advanced options of expensive equipment will remain unclaimed.

Thermostat - do it yourself

Despite the large selection of finished products, many people prefer to assemble a thermostat scheme for an incubator with their own hands. The simplest option presented below was one of the most popular amateur radio designs in the 1980s. The simple assembly and the available element base were dragging the flaws - dependence on the room temperature and instability to network interference.

Radio amateur circuits on operational amplifiers often outperformed their industrial counterparts. One of such schemes, assembled at OU KR140UD6, can even be repeated for beginners. All the details are found in household radio equipment of the end of the last century. With good components, the circuit starts working immediately and needs only calibration. If desired, you can find similar solutions on other OU.

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

The speed of operation of the regulator directly depends on the mass of the thermal sensor, because an excessively massive body has great inertia. You can “chop up” the sensitivity of a miniature thermistor or diode by putting a plastic cambric on the part. Sometimes for tightness it is filled with epoxy resin. For single-row designs with top heating, it is better 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 fascinating. Combined with technical creativity, for many it becomes a hobby for life. Do not be afraid to experiment and wish you a successful implementation of projects!

Choice of regulator circuit

If we take as a basis for the manufacture of the thermostat factory products, you can face insurmountable difficulties in assembling, and especially in setting up such products.

To get around the extra problems, it is best to choose the product scheme available for manufacturing at home.

The main criterion for any type of thermostat is to ensure high sensitivity to internal temperature inside the incubator, as well as an instant response to these changes. In most cases, “home-builders” use two options for building regulators:

1. Construction of the device based on the electrical circuit and radio components. The method is difficult and affordable for trained professionals
2. Making a regulator based on a thermostat from household appliances.

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

Manufacturing of temperature controller based on the scheme and radio components

The figure below shows a schematic diagram of a home-made temperature regulator during incubation.

If we carefully examine the scheme of this device, we can be sure that its assembly requires widespread radio components.

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For self-manufacturing device will need to purchase the following radio components:

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

In the scheme presented on drawing, temperature sensor appears VT1 transistorwhich is placed in a glass tube and laid directly on tray with eggs. When you turn on the controller in the network, triggered the relay, its contacts open and the incubator is heated by lamps that connect to the network 220 volt.

With disconnected from the network, relay contacts lock in and connect to work battery and car heating lamps. Upon renewal supply voltage, the relay is triggered again and connects the second pair of contacts charger device for recharging the battery. Variable resistor is set threshold required temperature. Special requirements to charger not, you can use any available.

Thermostat as a regulator

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

It needs a certain way to prepare for work. To do this, in any way possible fill the thermostat housing with ether and solder well.

The air reacts very sensitively to the slightest change in the outside temperature, which leads to a change in the state of the thermostat housing. The screw that is soldered to the case is rigidly connected to the contacts. At the right moment, the heating element is turned on or off. The desired temperature is set when the adjustment screw is rotated (number 6 in the figure).

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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 manufacture the thermostat in the incubator. This can be done even by a schoolboy who enjoys radio electronics. The scheme does not contain scarce radio components. Elements are mounted on a printed circuit board or mounted by mounting.

If an “electric hen” is independently produced, it is useful to increase the percentage of hatching of young poultry, to provide a device for automatic turning of eggs in an incubator.
From this video you will learn how to make a thermostat for an incubator with your own hands: