How to assemble a thermostat at home. W1209 Thermal relay (programmable thermostat) with sealed sensor Thermal relay 12 volts

Hello to all lovers of electronic homemade products. Recently, I quickly made an electronic thermostat with my own hands, the device diagram is very simple. As an actuator, an electromagnetic relay with powerful contacts is used that can withstand currents up to 30 amperes. Therefore, the considered homemade product can be used for various household needs.

According to the scheme below, the thermostat can be used, for example, for an aquarium or for storing vegetables. For someone it can be useful when used in conjunction with an electric boiler, and someone can adapt it for a refrigerator.

Do-it-yourself electronic thermostat, device diagram

As I said, the circuit is very simple, contains a minimum of inexpensive and common radio components. Typically, thermostats are built on a comparator chip. Because of this, the device becomes more complicated. This homemade product is built on an adjustable zener diode TL431:

Now let's talk more about the details that I used.

Device details:

12 volt step down transformer
Diodes; IN4007, or others with similar specifications 6 pcs.
electrolytic capacitors; 1000 microns, 2000 microns, 47 microns
Chip stabilizer; 7805 or other 5 volt
Transistor; KT 814A, or another p-n-p with a collector current of at least 0.3 A
Adjustable zener diode; TL431 or Soviet KR142EN19A
Resistors; 4.7 kΩ, 160 kΩ, 150 ohm, 910 ohm
Variable resistor; 150 Kom
Thermistor as a sensor; about 50 kw with negative tks
Light-emitting diode; any with the lowest current consumption
Relay electromagnetic; any 12 volt with a current consumption of 100 mA or less
Button or toggle switch; for manual control

How to make a thermostat with your own hands

The burned-out electronic counter Granit-1 was used as a case. The board on which all the main radio components are located is also from the meter. Inside the case fit a power supply transformer and an electromagnetic relay:

As a relay, I decided to use an automotive one, which can be purchased at any car dealer. Coil operating current approximately 100 milliamps:

Since the adjustable zener diode is low-power, its maximum current does not exceed 100 milliamps, it will not work to directly connect the relay to the zener diode circuit. Therefore, I had to use a more powerful transistor KT814. Of course, the circuit can be simplified if a relay is used, in which the current through the coil will be less than 100 milliamps, for example, or SRA-12VDC-AL. Such relays can be connected directly to the zener diode cathode circuit.

I'll talk a little about the transformer. As which I decided to use non-standard. I have a voltage coil from an old induction electric energy meter lying around:

As you can see in the photo, there is free space for the secondary winding, I decided to try winding it and see what happens. Of course, the cross-sectional area of \u200b\u200bthe core is small, and, accordingly, the power is small. But for this temperature controller, this transformer is enough. According to my calculations, I got 45 turns per 1 volt. To get 12 volts at the output, you need to wind 540 turns. To fit them, I used a wire with a diameter of 0.4 mm. Of course, you can use a ready-made one with an output voltage of 12 volts or an adapter.

As you noticed, the circuit has a 7805 stabilizer with a stabilized output voltage of 5 volts, which feeds the control output of the zener diode. Thanks to this, the temperature controller turned out with stable characteristics that will not change from changes in the supply voltage.

As a sensor, I used a thermistor, which at room temperature has a resistance of 50 kΩ. When heated, the resistance of this resistor decreases:

To protect it from mechanical influences, I used heat-shrinkable tubes:

The place for the variable resistor R1 was found on the right side of the thermostat. Since the axis of the resistor is very short, I had to solder a flag on it, for which it is convenient to turn. On the left side, I placed the manual control toggle switch. With it, it is easy to control the operating state of the device, while not changing the set temperature:

Despite the fact that the terminal block of the former electric meter is very bulky, I did not remove it from the case. It clearly includes a plug from any device, such as an electric heater. By removing the jumper (yellow on the right in the photo) and turning on the ammeter instead of the jumper, you can measure the current supplied to the load:

Now it remains to calibrate the thermostat. For this we need . It is necessary to connect both sensors of the device together with electrical tape:

Use a thermometer to measure the temperature of various hot and cold objects. Using a marker, apply a scale and markings on the thermostat, the moment the relay is turned on. I got from 8 to 60 degrees Celsius. If someone needs to shift the operating temperature in one direction or another, this is easy to do by changing the values of the resistors R1, R2, R3:

So we made an electronic thermostat with our own hands. Outwardly it looks like this:

In order not to see the inside of the device, through the transparent cover, I covered it with adhesive tape, leaving a hole for the HL1 LED. Some radio amateurs who decide to repeat this scheme complain that the relay turns on, not very clearly, as if rattling. I did not notice anything, the relay turns on and off very clearly. Even with a slight change in temperature, no chatter occurs. If, nevertheless, it arises, it is necessary to select more accurately the capacitor C3 and the resistor R5 in the base circuit of the KT814 transistor.

The assembled thermostat according to this scheme turns on the load when the temperature drops. If someone, on the contrary, needs to turn on the load when the temperature rises, then you need to swap the sensor R2 with resistors R1, R3.

Thermostat for incubator Mechta-12 (12V) with control and regulation of humidity level, as well as a programmable timer for turning / changing the position of the trays in the incubator, this is a universal electronic device that will provide high-quality and reliable automatic control temperature and humidity in the incubator that you need. Provides control of the rotation of the trays at specified time intervals. The device has a high measurement and adjustment accuracy. Temperature - 0.1 °C. Humidity - 5%. Supply voltage 12 V.

Purpose and main characteristics

Any egg incubators require constant monitoring of ambient temperature and humidity. The main difficulty in this is to maintain these parameters in constant values! Indeed, even a 10-minute overheating or hypothermia of incubated eggs leads to the death of the embryo.

Humidity also plays an important role in incubation. To measure humidity, a psychrometric method is used, based on the dependence of the difference between the readings of the dry and wet thermometers of the device. This method is one of the most accurate and reliable. You can read more about this method below.

It is also necessary to turn the eggs after a certain time (at least 3-4 turns per day) throughout the entire period of incubation, this is due to the fact that the temperature difference on different sides of the eggs can reach 2 degrees, which leads to a decrease in the hatching of chicks.

To solve these problems, it is necessary to use various temperature and humidity control devices, various timers. Electronic device DREAM-12 combines all these functions in one device, designed and used to control temperature and humidity parameters, as well as to control tray turners in incubators.

DREAM-12 is the control device of the I&C. The device analyzes the information coming from the sensors, analyzes the time intervals, and by means of a relay switches the load on external devices that serve to change the climatic conditions in the regulated object, and also, if it is an incubator, it turns on the engine of the tray turning device.

To change the temperature, any heating or cooling devices with a current consumption of not more than 16 A can be used - electric tubular electric heaters (TEH), incandescent bulbs, air conditioners, refrigeration units, etc.

To regulate the humidity in the incubator, ultrasonic humidifiers, steam generators, valves of a device that supplies water to wet hanging tissue, heated water tanks, compressors pumping air through water tanks, etc. can be connected. Ventilation systems can be connected to the instrument to reduce humidity.

In addition to incubators, the device can also be used to measure and control temperature and humidity in various types of premises (storages, greenhouses), in drying chambers, in domestic conditions, as an integral part of a weather station, etc.

Description of the appearance of the device device
On the front panel of this model is:
1. digital indicator displaying the current values of temperature, humidity, service information, as well as the state of the load (on or off)
2. control buttons (with the help of which user information is entered into the microcontroller):
M - menu; rank change.
OK - confirmation; change in the number in the discharge.
For adjustment and maintenance during operation, it is possible to enter the service menu. Adjustable device parameters:
- Operating time of the timer of turn of trays;
- Temperature value;
- Humidity value;
- Hysteresis parameters;
- Service parameters from the service menu.

Description psychrometric method“dry-wet bulb”: a “dry” thermometer shows the temperature of the surrounding air, and a “wet” thermometer, partially placed in distilled water, shows a lower temperature, since water evaporates from its surface, associated with heat consumption. Evaporation from the surface of a wet bulb thermometer is the more intense, the lower the humidity of the surrounding air. The difference in the readings of the thermometers therefore depends on the value of the air humidity. The lower the air humidity, the greater the evaporation rate and the greater the difference in thermometer readings. Knowing the temperature difference, you can use a special psychrometric table and find out the humidity value.

Warranty: 24 months

The TR-12V-DS universal digital temperature controller is designed to measure and maintain the temperature within the specified limits (from -55 to +125°C), and can be widely used for precise temperature control in electrical circuits with a voltage of 12 V.

Application area

The TR-12V-DS thermostat is most in demand for use in automotive equipment with an on-board network of 12V; can be used in incubators, brooders; in various systems based on batteries, solar panels and other alternative energy sources; in equipment powered by 12 volts. The temperature sensor is a widely used high-precision digital sensor DS18B20.

Functionality

The climate control thermostat TR-12V-DS measures the temperature value at the location of the sensor and gives a command to turn the load on or off by means of an electromagnetic relay. Any heating or cooling electrical appliances are connected to it. At the same time, the maximum power of connected devices should not exceed 2500 watts of active load (10 amperes at cos ? = 1).

The device has settings for the temperature to be maintained, and hysteresis, that is, the temperature difference between switching on and off the load, so you can set a wider temperature "corridor" and avoid excessive relay operation. The TR-12V-DS universal thermostat can be configured both for heating mode (turning on the heating device when the temperature drops below the set one) and for cooling mode (turning on the cooling device when the temperature rises above the set one). In addition, the thermostat has a built-in timer, thanks to which it is possible to program the thermostat to maintain the temperature for a certain time (temperature maintenance X minutes -> turn off before manual activation) or to work in a cyclic mode (temperature maintenance X minutes -> simple Y minutes -> temperature maintenance...). Also, the device has the ability to limit the set upper and lower limits of the range of maintained temperature.

The thermostat comes in a small transparent case 6 (8) x 5 x 3 cm and has holes for fastening with self-tapping screws (screws) on any suitable surface.

Specifications

Parameter	Meaning
Measuring temperature range	from -55 to +125 °С
Resolution	0.1 °С, 0.1 °С in the range from -9.9 to +99.9 °С, 1 °С in the range from -55 to -10 °С and from +100 to +125 °С
Temperature measurement error
Hysteresis (difference between switch-on and switch-off temperatures)	plus or minus from 0 to 50.0 °С
Work timer time	0 to 999 minutes
idle timer time	0 to 999 minutes
Sound signaling of the end of the process
Choice of operation logic	heating or cooling
Maximum switching current at cos ? =1
Length of connecting wires of the sensor
Instrument supply voltage	12 Volt AC/DC
Mounting method (connection)	flat surface, portable cabinet
dimensions	6 (8) x 5 x 3 cm

The W1209 thermal relay module is designed to control temperature in the range from -50 to +100 degrees. Equipped with a 3-character LED display, a relay on indicator, three buttons for controlling an electronic temperature controller, a connector for connecting an external temperature sensor, terminals "K0/K1" for connecting a load and "+12V/GND" for powering the thermostat board. The display shows the current measured temperature from the sensor, "LL" - if the sensor is not connected, and "HH" - if the temperature is out of range.

Characteristics of the thermal relay W1209:

Thermistor	NTC (10K 0.5%) waterproof sensor
Temperature Range	-50°C to +110°C
Measurement accuracy
Control accuracy	0.1°C in the range -9.9°C to 99.9°C, or 1.0°C outside this range
Update time	0.5 seconds
Hysteresis (lag)	0.1°C ....... 5°C
Hysteresis accuracy (lag)	0.1°C
Supply voltage	DC 12V
Quiescent current	< 35 мА
Operating current	< 65 мA
Output voltage	DC 12V
Maximum load current	5A/AC 125V, 15A/DC 14V
Permissible humidity	20% to 85% Rh
Length of cable	0.3 meters
Dimensions	48mm*40mm

The LED display shows the following values:

"LLL" - The sensor is not connected
"HHH" - Temperature out of range (less than -50°C or more than 110°C)
"- - -" - Exceeding the limits set in parameter P6

Preparation for work:

Connect a 12V DC power supply to the contacts "+12V" (plus 12V) and "GND" (minus 12V)
Connect the load to the contacts "K0" and "K1" (connected to the break in the power supply circuit of the controlled device - serial connection)

After applying 12V power to the contacts "+12V" and "GND", the LED display will display the current temperature measured by the remote temperature sensor

Setting and setting the set temperature:

To set the control temperature, briefly press the "SET" button. then use the "+" and "-" buttons to set the desired temperature. After setting the temperature, press the “SET” button again, or do not press any buttons for 5 seconds.

Programming:

To enter the programming mode, press the "SET" button for 5 seconds!
Use the "+" and "-" buttons to select the menu parameter code (P0....P6) from the "Temperature controller menu" table
To set the parameter, press the “SET” button and use the “+” and “-” buttons to change the parameter value
To save the settings, press the “SET” button, or do not press any buttons for 5 seconds.

To reset parameters to factory settings (default settings):

Turn off the power
Press and hold the "+" and "-" buttons
Apply power to the thermostat

The LED display will show "888" followed by the current temperature.

Application area

Functionality

The thermostat comes in a small transparent case 6 (8) x 5 x 3 cm and has holes for fastening with self-tapping screws (screws) on any suitable surface.

Specifications

Parameter	Meaning
Measuring temperature range	from -55 to +125 °С
Resolution	0.1 °С, 0.1 °С in the range from -9.9 to +99.9 °С, 1 °С in the range from -55 to -10 °С and from +100 to +125 °С
Temperature measurement error
Hysteresis (difference between switch-on and switch-off temperatures)	plus or minus from 0 to 50.0 °С
Work timer time	0 to 999 minutes
idle timer time	0 to 999 minutes
Sound signaling of the end of the process
Choice of operation logic	heating or cooling
Maximum switching current at cos ? =1
Length of connecting wires of the sensor
Instrument supply voltage	12 Volt AC/DC
Mounting method (connection)	flat surface, portable cabinet
dimensions	6 (8) x 5 x 3 cm

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