Your footnote doesn't work. This is some kind of forum where it’s not clear where to look for thermometers.
To make your problem clear to me, tell me how many eggs the incubator is planned for? I think there is no point in repeating the industrial scheme. You can take from it the basic parameters to ensure % hatching of eggs. This rotation must occur every hour. The rotation pattern must be equipped with a rotation counter. Otherwise, you won't know whether the turns work or not.
It is correct that the circuit is 12 volt. It is possible, during the incubation period, to supply a battery as a backup power supply. The inside of the chamber should be equipped with a fan that runs throughout the incubation period. But, once a day, the incubator turns off for 40 minutes - 1 hour, its doors open for free access of air. This is an imitation of the chicken going about its business, like eating, for example.
If there are a lot of eggs, well, 400 - 500 eggs, the incubator must be equipped with a cooling system. In the initial stage of incubation, a few days after the eggs are laid, they themselves begin to generate heat, and the heat loss through the walls of the incubator may not be enough to maintain a normal temperature in the incubator. Temperature variation is allowed +/- 0.3 C. In reality, it fluctuates +/- 0.1 - 0.15 degrees. In addition, a ventilation system must be provided - a constant flow of fresh air in small quantities. Otherwise the egg will suffocate. And in this regard, you cannot wash the hatching egg - its pores become clogged. On the other hand, it must be clean. In life, a chicken cleans an egg with its feathers. I didn’t know or forgot how this is done in the incubator. There is an assumption that it is cleaned with brushes, but I don’t know exactly how they do it in this case. I don't think I have anyone to ask. I also don’t remember how the egg goes into the tray (I never put it there, I just saw it), but I know for sure - not haphazardly. I am writing this so that you will pay attention to this.
Humidity control is carried out with a psychrometer. This end with mercury of an electric contact thermometer is wrapped in 3-4 layers of gauze (a narrow bandage) to which water is constantly supplied (the bandage is wet). With normal humidity in the incubator, the temperature on the thermometer is 7 degrees. less than the incubator temperature. (If you have the opportunity to check this, check it, I could also have forgotten) I stopped working as a poultry house power engineer in 1987, quite some time has passed. An increase in humidity in the incubator is achieved by dripping water onto the heating elements (heaters), and since they are quite hot, the water immediately evaporates. When the required humidity is reached, the solenoid valve shuts off the water supply.
i.caam.ru/sales/prom/rtutnij_kontaktnij_...H00030d04_339293.jpg
The eggs are placed vertically in the tray, with a blunt
end up, in a checkerboard pattern. In trays,
designed for chicken eggs, quail
eggs can be laid in two rows, and the day before
transfer the hatchlings to brood trays.
After filling the tray with eggs, it is advisable to
disinfect. The most accessible
method is household treatment
ultraviolet emitter for 5-8
min. from a distance of 40 cm.
"Start" is a regular toggle switch with a lock.
If, suddenly, something is not clear from the diagram, ask. TYPOGRAPHY - connect output DD1.3 and input DD1.4 together.
I suggest you assemble a working incubator with automatic egg turning. To make a homemade incubator with your own hands with automatic egg turning, we will need a time relay and a wiring diagram for the RD-09 reversible motor.
The operating principle of an electronic time relay is based on the charging and discharging time of a capacitor. Having correctly selected the ratio of resistance R1 and capacitance of capacitor C1, we can select any response time. but you need to take into account that the charging and discharging times of the capacitor are the same, that is, an incubator with automatic egg turning is suitable for us for that simple reason. that the revolution occurs at equal periods of time - 2 hours. We select the resistance and capacitance so that the discharge/charge periods are equal to 2 hours. On the diagram of an electronic time relay it looks like this - as soon as a full charge or full discharge occurs, the microcircuit emits a signal to the base of the transistor, which operates in electronic key mode. The transistor, in turn, is either open or closed. It either supplies current to power the relay coil, or does not supply it, which activates the contacts of the relay. And the relay, in turn, controls the RD-09 reversible engine.
Connection diagram for reversible engine RD-09 No. 1:
Connection diagram for reversible engine RD-09 No. 2:
The operating principle of the reversible engine is also extremely simple. Controlled by a relay, it rotates in one direction or the other at regular intervals. By driving the actuator to mechanically turn the trays with eggs in the incubator. Thus, we achieve our goal - a homemade incubator with automatic egg turning. Microswitches serve to ensure that the driven mechanical part- an actuator that stopped the trays in strictly specified ranges, at a strictly defined angle of rotation or tilt of the incubator trays with automatic egg turning. This results in a perfectly working device, which, thanks to a minimum of inexpensive parts, can be assembled yourself. For another version of the scheme, see the link.
Continuing the topic of Automatic egg turning in a homemade incubator:
Automatic time relay (timer) APL-3 is used for turning eggs in the incubator.
New model! With universal timer power supply from 220V or 12 volts.
The device is used to form cyclic time delays at intervals specified in the device settings and to supply control voltage to the electric drive of tray rotating devices in incubators. The minutes timer can set a time interval from 1 to 999 minutes, and the seconds timer can set a time interval from 1 to 999 seconds. The device can be used to control other devices that are suitable for this operating logic.
The APL-3 device is designed to control reversible (RD-09, RD-54) and non-reversible engines alternating current powered from a 220 volt network, as well as DC motors with permanent magnets with a supply voltage of 12 volts.
It is possible to use electric motors from 12 volt screwdrivers or from electric car locks. Engines can be purchased at technical markets or in repair shops for the relevant products. Recommendations are conditional, there may be other options.
The cycle time is set by the consumer by programming the device depending on the connection diagram used.
The device is operational with an input power of 12 volts DC or 220 volts alternating current and switches a current of no more than 10 Amps. If there is a small zero on the device indicator, the relay is de-energized, if there is a lightning sign, the voltage is applied to the relay. After applying voltage to the device, you can program the required time delays. To do this, select the desired parameter by pressing the button, confirm with the button and enter the parameter value. Then, using the same buttons, you can change the value of the parameters. After setting the parameter value, as well as after the last pressing of any button, after 5 seconds the system saves the set values in non-volatile memory and goes into the main mode of processing parameters.
After setting the parameters, it is necessary to remove the supply voltage and reapply it.
The system will begin to process the set values.
BP1 is a parameter in which the cycle time is set in minutes from 1 to 999. For example, by setting the number 120, the device turns on the relay for 2 hours, and then turns it off for 2 hours, then turns it on again for 2 hours, and so on in a cycle until there is power voltage. If during operation you remove and then reapply the supply voltage, the time countdown will begin again. This parameter is used in circuits using reversible motors.
BP2 is a parameter in which the time is set in seconds from 1 to 999. This parameter is used when a circuit with a non-reversible motor is used. If a number other than zero is specified in this parameter, the operating logic of the device will be as follows: the time specified in parameter BP1 is processed while this relay is turned off, after this time the relay is turned on for the time specified in the parameter, then turned off again for the time specified in and so on in a cycle until supply voltage is present. For example, in the number 60, and in the number 20. In this case, the engine will turn on for 20 seconds every hour.
Video inspection:
In our difficult times, when prices for goods are rising at an inexorable pace, you will always find an area in which you can profitably apply your practical skills and theoretical knowledge. By looking at the cost of an industrially produced incubator, you can easily calculate the benefits of making such a device yourself. Moreover, making a home incubator with your own hands is not so difficult.
This is what a forum user says about his homemade incubator with mechanical egg turning geniuscat.
geniuscat
Briefly: an incubator for 60-70 chicken eggs, the turning is mechanical using a special grid, I don’t do it automatically at all. Heating using light bulbs, two chains. Temperature control using an electric contact thermometer. I don't trust electronics. Temperature spread across corners is 0.5 degrees. Cheap and cheerful. If you have the components, you can make an incubator in 3-4 hours.
The most important thing in manufacturing is to ensure the ability to maintain optimal humidity and temperature inside the device, as well as create conditions for timely turning of the eggs in order to heat them evenly.
Incubator body
In most cases, the basis of everything is the body. And the incubator in in this case is no exception.
When manufacturing the case, special attention should be paid to ensuring good thermal insulation for the future device. This will allow you to avoid future troubles associated with compliance with strict temperature regime in the incubation chamber.
For the manufacture of the case, porous polymer materials, penoplex (expanded polystyrene) 20 mm thick, etc. are quite suitable. You can also use fiberboard or chipboard sheets, but you should create double walls with foam, felt or foam core.
The size of the incubator will directly depend on the number of eggs that are planned to be placed in the chamber at the same time. The height of the inner chamber of 50 cm will be quite enough. The area of the inner base will be equal to the area of the egg tray. But you need to add about 50 mm to it on each side. This is the gap that should be between the tray and the incubator body to ensure air circulation. Several holes with a diameter of 10 mm must be drilled in the lower base of the incubator, through which air exchange will take place between the internal space of the chamber and the external environment (the incubator must be constantly enriched with oxygen). For an incubator designed for 50 eggs, 6 holes are enough.
Attention! The lower holes should be positioned in such a way that they are not blocked by a baking tray (plate) with water, which will be installed in the chamber to maintain a sufficient level of humidity.
To ensure unhindered air movement between the bottom of the device and the surface on which it will be installed, there must be a gap of 30...50 mm. A viewing window of 100x100 mm, covered with glass, should be made in its top cover. If there is no forced ventilation in the incubator, then the glass should be opened slightly during operation, leaving a gap of 10...15 mm.
And one more nuance: one of the side surfaces of the incubator must have a door for changing water and other actions related to servicing the chamber.
Incubator tray
In order for the eggs to be carefully placed in the interior of the incubator, we need to make a special tray. In our case, it can be made on the basis of a wooden frame, which is covered with a fine mesh underneath. Both an ordinary mosquito net, used in the construction of modern double-glazed window windows, and a metal (maybe different) mesh with a cell size comparable to 5x5 mm (but no more) are suitable as a mesh. In order to prevent the mesh from sagging, a couple of small slats can be nailed to the bottom of the tray, which will comprehensively strengthen the structure of the tray.
To make it more convenient to turn the eggs during incubation, the tray should be equipped with an insertable wooden grid. For convenience, you can make several gratings at once, with different sizes of internal cells. So, for quail eggs, a grid with a cell size of 45x35 mm is suitable; for chicken eggs, cells measuring 67x75 mm are needed. If you want to put goose eggs in the incubator, then the cells must be of the appropriate size - 90x60 mm. The width of the grid should be 5 mm smaller than the tray itself. The length should be shorter by 50...60 mm - for quail eggs, 80...90 mm - for chicken eggs and 100...110 mm - for goose eggs. Thus, by moving the grill along the tray, you can turn the eggs 180 degrees. In order to heat the eggs evenly over time, a similar procedure should be performed approximately once every 2 to 3 hours.
Egg turning tray
The height of the sides of the tray itself should be 70–80 mm. The tray should be installed on legs 100 mm high.
This is the most simple design tray, allowing you to turn all the eggs at the same time. But in order to make the incubator design more modern, the process of turning eggs can be automated. And this will require some technical improvements.
How to make a revolution in an incubator
In order to automate the process of turning eggs in the incubator, it is necessary to introduce an electromechanical drive into its design, which is activated after a certain period of time (as we have already said, it is 2–3 hours). The accuracy of the time interval will be ensured by a special time relay. The relay can be purchased ready-made. Those who like to tinker with microcircuits can make it themselves, using electronic or even mechanical watches, which are easy to buy in Moscow and in any village.
Here is what user FORUMHOUSE writes about this.
mednagolov
Nowadays it is easy to purchase Chinese electromechanical relays with a 24-hour cycle. In essence, this is a basic watch with a plug that plugs into a socket, and on the body of this watch there is a socket into which the consumer plugs, inside the clock a tiny electric motor turns. There is no need to wind them up; along the circle of the dial, marked out for 24 hours, there are “pressers” with which you set the time intervals.
The electric motor must transmit torque through the gearbox. This will help make the grate move smoothly and keep the eggs intact.
The tray grid should move along the guides. The walls of the tray can play the role of guides. But to avoid accidental jamming, this mechanism can be improved. To do this, a metal axis protruding from both ends should be attached along the central axis of the grille. She will play the role of a reliable guide. The axis will be inserted into special grooves made on the sides of the tray. This design is reliable, it can be easily assembled and, if necessary, quickly disassembled.
In order to drive the grid with eggs, we need a reciprocating mechanism consisting of an electric motor, a gearbox, a crank mechanism and a rod connecting the drive to the tray grid.
A device for turning eggs in an incubator.
As an electric motor, you can use special “motors” for microwave ovens, which are commercially available. Also, some craftsmen create an electromechanical drive based on the mechanism that is part of car wipers. Or here’s a way out of the situation that forum member Mednagolov came up with: the drive of the egg turning mechanism is electric. ball valve motor remote control d=3/4 220v (has an extremely powerful and durable gearbox, as well as microswitches for end positions).
He used the power supply from an old computer, and the time relay - a mechanism from a Chinese watch, which was written about just above.
The mechanism functions as follows: the relay closes the electrical circuit after a specified period of time. The mechanism is driven and moves the tray grid, turning the eggs. Then the limit position switches (limit switches) are activated and the grille is fixed in the opposite extreme position. After a specified time, the cycle is repeated, and the grate returns to its original position. The entire homemade process occurs without human intervention.
Incubator heating
Proper placement of heating elements in the incubator chamber is the key to success, ensuring the hatching of healthy and strong chicks. It is customary to use ordinary incandescent light bulbs as heating elements. Ideally, they are best installed above the tray with eggs, evenly spaced around the perimeter of the incubator. The tray and the heating element must be separated by a distance of at least 25 cm. In a homemade incubator, low-power light bulbs of 25 watts, etc. should be used. The total power of the heating elements used in such an incubator should be 80 watts - for a device designed for the simultaneous hatching of 50 chicks.
The lower the power of the heating elements, the more evenly the heat is distributed in the incubation chamber.
When placing lamps on the walls of the chamber, you should also ensure that they are evenly positioned around the entire perimeter. Know that by using a series electrical connection of heating elements, you can significantly extend their service life. But the power of each consumer in this case will be halved. This should be taken into account when calculating the number of heating elements, because with the appropriate connection method the number of consumers will have to double.
Temperature control
As we already know, the temperature in the incubator chamber must exactly correspond to the specified parameters. Otherwise, such a device is worthless. The optimal temperature for hatching chickens in artificial conditions is from 37.5 to 38.3º C. But it must be strictly observed. A regular thermostat, which can be purchased in a store without any problems, will help maintain the specified range. It is necessary that this device provides an accuracy of temperature values corresponding to 0.2º C. An error greater than the presented value can be detrimental to developing embryos.
We think it will not be difficult to connect the thermostat to the heating elements for a person who has decided to make an incubator with his own hands. The main thing is to ensure that the temperature sensors are located near the egg tray. For more accurate readings, the sensors can even be mounted on a tray. As an additional means of control, a regular thermometer should be used. It is better if it is electronic, capable of displaying tenths of a degree. But in extreme cases, a regular alcohol thermometer will do. It should be secured in the chamber in such a way that it is located immediately above the tray. In this case, its readings can be taken by looking through the viewing glass.
Heat accumulator
JG_ FORUMHOUSE member
To make the temperature drop more slowly, you need to use a heat accumulator. I used water as TA. It provides humidification and also increases the temperature, and when turned off, it releases it for a long time, not allowing the temperature to drop quickly. Only the container with water should be large. You can just put a metal pancake or a dumbbell inside - why not?
It remains to add that without an air humidifier in the incubator, all your efforts are doomed to failure. Therefore, a baking tray or open plate filled with water can be considered one of the essential elements involved in the incubation process. As for the heat accumulator, a heating pad or plastic water bottle will never be out of place in the interior of your incubator.
Humidity can be monitored using a psychrometer, which can be purchased at a hardware store. The optimal humidity in the incubator should be 50–55% (immediately before hatching the chicks, it can be increased to 65–70%).
Incubator ventilation
Many owners of homemade incubators believe that the fan is an integral part of such a device. But practice shows that a small incubator, the number of eggs in which does not exceed 50, can do without forced ventilation. Convection of air in it occurs naturally and this is enough to support the vital activity of the embryos.
If your incubator chamber is designed for large quantity eggs, or if you want to create an ideal microclimate inside the device at all costs, then for these purposes you can use special fans with a diameter of 80 to 200 mm (depending on the volume of the chamber).
The fan can be mounted in the top cover of the incubator so that it takes air from the interior of the chamber. Part of the air flow will go out, and the main volume will be reflected from the lid and pass over the lower supply holes, mixing warm air with cold and enriching it with oxygen.
That's probably all. You can find out the various opinions of our users regarding the design, as well as get acquainted with their practical developments in this topic. We also have information for those interested in productivity. If you want to create more at home, the design of which contains powerful components and complex ventilation circuits, then you should visit this section.
All experienced poultry farmers know well that one of the main conditions for successful incubation of eggs, in addition to correctly selected temperature and humidity, is their periodic turning.
Moreover, this must be done using strictly defined technology. All existing incubators are divided into three groups - automatic, mechanical and manual, and the last two varieties assume that the process of turning eggs will be carried out not by a machine, but by a person.
A timer will help to simplify this task; if you have some time and experience, you can make it yourself. Several methods for making such a device are described below.
What is it needed for
The egg turning timer in the incubator is a device that opens and closes an electrical circuit after the same period of time, that is, speaking in simple language, primitive relay. Our task is to turn off and then turn on the main components of the incubator, thus automating the system as much as possible and minimizing possible mistakes caused by human factor.
The timer, in addition to turning the eggs, also provides the following functions:
- temperature control;
- ensuring forced air exchange;
- starting and turning off lighting.
The microcircuit on the basis of which such a device is manufactured must meet two main conditions: low current switching with high resistance of the key element itself.
The best option in this case is the construction technology electronic circuits CMOS, which has both n- and p-channel field effect transistors, which provides higher switching speed and is also energy saving.
The easiest way at home is to use timing chips K176IE5 or KR512PS10, sold in any electronics store. Based on them, the timer will work for a long time and, most importantly, uninterruptedly. 
The operating principle of the device, made on the basis of the K176IE5 microcircuit, involves the sequential execution of six actions:
- The system starts (circuit closure).
- Pause.
- A pulse voltage is applied to the LED (thirty-two cycles).
- The resistor turns off.
- A charge is supplied to the node.
- The system turns off (circuit open).
Important! If necessary, the response time can be extended to 48–72 hours, but this will require upgrading the circuit with higher power transistors.
Timer,
made on the KR512PS10 chip, in general, is also quite simple, but there are additional functionality, due to the initial presence in the circuit of inputs with a variable division coefficient. Thus, to ensure the operation of the timer (the exact response delay time), you need to correctly select R1, C1 and install the required number of jumpers. 
There are three possible options here:
- 0.1 seconds–1 minute;
- 1 minute–1 hour;
- 1 hour–24 hours.
If the K176IE5 chip assumes the only possible cycle of actions, then on the KR512PS10 the timer operates in two different modes: variable or constant.
In the first case, the system turns on and off automatically, at regular intervals (the mode is configured using jumper S1), in the second, the system turns on with a programmed delay once and then works until it is forced to turn off.
To implement the creative task, in addition to the timing chips themselves, we will need the following materials:
- resistors of various powers;
- several additional LEDs (3–4 pieces);
- tin and rosin.
The set of tools is quite standard:
- a sharp knife with a narrow blade (to short-circuit resistors);
- a good soldering iron for microcircuits (with a thin tip);
- stopwatch or watch with a second hand;
- pliers;
- screwdriver-tester with voltage indicator.
Homemade incubator timer with your own hands on the K176IE5 chip
Most electronic devices, such as the incubator timer in question, have been known since Soviet times. An example of the implementation of a two-interval timer for incubating eggs with detailed instructions was published in the magazine “Radio”, popular among radio amateurs (No. 1, 1988). But, as you know, everything new is well forgotten old.
If you are lucky enough to find a ready-made radio designer based on the K176IE5 chip with already etched printed circuit board, then assembling and setting up the finished device will turn out to be a simple formality (the ability to hold a soldering iron in your hands, of course, is highly desirable).
Let's look at the stage of setting time intervals in more detail. The two-interval timer in question provides alternation of the “operation” mode (the control relay is turned on, the incubator tray rotation mechanism is working) with the “pause” mode (the control relay is turned off, the incubator tray rotation mechanism is stopped).
The “work” mode is short-term and lasts between 30–60 seconds (the time required to rotate the tray to a certain angle depends on the type of specific incubator).
Important! At the stage of assembling the device, you should strictly follow the instructions to avoid overheating in the soldering areas of electronic semiconductor components (mainly the main microcircuit and transistors).
The “pause” mode is long and can last up to 5 or 6 hours (depending on the size of the eggs and the heating capacity of the incubator.)
For ease of setup, the circuit includes an LED, which will blink at a certain frequency while setting time intervals. The LED power is adjusted to the circuit using resistor R6.
The duration of these modes is adjusted by timing resistors R3 and R4. It should be noted that the duration of the “pause” mode depends on the value of both resistors, while the duration of the operating mode is set exclusively by resistance R3. 
For fine tuning, it is recommended to use variable resistors 3–5 kOhm for R3 and 500–1500 kOhm for R4 as R3 and R4, respectively.
Important! The lower the resistance of the timing resistors, the more frequently the LED will flash and the shorter the cycle time will be.
Adjusting the “work” mode:- short-circuit resistor R4 (reduce resistance R4 to zero);
- turn on the device;
- Use resistor R3 to adjust the blinking frequency of the LED. The duration of the “work” mode will correspond to thirty-two flashes.
Adjusting the pause mode:
- use resistor R4 (increase resistance R4 to nominal);
- turn on the device;
- Use a stopwatch to measure the time between adjacent LED flashes.
The duration of the “pause” mode will be equal to the received time multiplied by 32.
Instructions: how to make your own incubator timer using the KR512PS10 chip
The KR512PS10 microcircuit, manufactured on the basis of the CMOS technical process, is used in a wide variety of electronic timer devices with a variable time cycle division coefficient.
These devices can provide both one-time switching on (switching on the operating mode after a certain pause and holding it until forced shutdown), and cyclic switching on and off according to a given program.
Did you know? The chick in the egg breathes atmospheric air, which penetrates the shell through the smallest pores in it. By letting in oxygen, the shell simultaneously removes carbon dioxide exhaled by the chicken, as well as excess moisture, from the egg.
Creating a timer for an incubator based on one of these devices will not be difficult. Moreover, you don’t even have to pick up a soldering iron, since the range of industrially produced boards based on KR512PS10 is extremely wide, their functionality is diverse, and the ability to configure time intervals covers the range from tenths of a second to 24 hours. 
Ready-made boards are equipped with the necessary automation, providing quick and accurate adjustment of the “work” and “pause” modes. Thus, making a timer for an incubator on the KR512PS10 microcircuit comes down to the correct choice of board for the specific characteristics of a particular incubator.
If you still need to change the operating time, you can do this by short-circuiting resistor R1.
For those who love and know how to solder, and also want to assemble such a device with their own hands, we present one of the possible diagrams with a list of electronic components and a printed circuit board trace. 
The described timers are applicable to control the rotation of the tray when working with household incubators with periodic switching on of the heating elements. In fact, they allow you to synchronize the movement of the tray with turning the heater on and off, repeating the entire process cyclically.
Other options
In addition to the considered options for basic microcircuits, there are many electronic components on which you can build a reliable and durable device - a timer.
Among them are:
- MC14536BCP;
- CD4536B (with modifications CD43***, CD41***);
- NE555, etc.
Some of these microcircuits have now been discontinued and replaced with modern analogues (the electronic components production industry does not stand still).
All of them differ in secondary parameters, an expanded range of supply voltages, thermal characteristics, etc., but at the same time they perform all the same tasks: turning on and off a controlled electrical circuit according to a given program. 
The principle of setting the working intervals of the assembled board is the same:
- find and short-circuit the “pause” mode resistor;
- use the “operation” mode resistor to set the desired blinking frequency of the diode;
- unlock the pause mode resistor and measure the exact operating time;
- set divider parameters;
- place the board in a protective case.
When making a tray turn-over timer, you need to understand that this is, first of all, a timer - a universal device, the scope of which is not limited solely to the task of turning the tray over in an incubator.
Subsequently, having gained some experience, you will be able to equip heating elements, lighting and ventilation systems with similar devices, and later, after some modernization, use it as the basis for automatically supplying feed and water to chickens.
Did you know? Many people believe that the yolk in an egg represents the embryo of the future chicken, and the white is the nutrient medium necessary for its development. However, in reality this is not the case. The chick begins to develop from the germinal disc, which in the fertilized egg looks like a small light-colored speck in the yolk. The chick feeds mainly on the yolk, while the protein is for the embryo a source of water and useful minerals necessary for normal development.
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