How to make a thermoregulator with your own hands. Thermoregulator for the aquarium or for heating by one's own hands

The Russian winter is distinguished by its severity and severe colds, as is known to everyone. Therefore, the premises in which people are located should be heated. Central heating is the most common option, and in case of its inaccessibility it is possible to use an individual gas boiler. However, it often happens that neither is not available, for example, in a clean field there is a small room of a pumping water station, in which the drivers are on duty around the clock. This could be a room in some large uninhabited building or a watchtower. There are enough examples.

Way out

All these cases are forced to carry out the device of electric heating. At small dimensions of the room it is quite possible to do with an ordinary electric oil cooler, and in larger rooms, water heating using a radiator is most often arranged. If you do not monitor the temperature of the water, then sooner or later it can boil, because of which the entire boiler will fail. Thermoregulators are used to protect against such cases.

Device Features

In functional terms, the device can be divided into several separate units: a temperature sensor, a comparator, as well as load control devices. Then all these parts will be described. This information is necessary in order to make the thermoregulator with your own hands. In this case, a design is proposed in which a conventional bipolar transistor serves as a temperature sensor, so that it is possible to refuse the use of thermistors. This sensor operates on the basis that the parameters of the transistors of all semiconductor devices are more dependent on the temperature of the medium.

Important nuances

The creation of a thermoregulator by one's own hands should be carried out with the obligatory consideration of two points. First, we are talking about the propensity of automatic devices for autogeneration. In the case where too strong a connection is established between the actuator and the thermostat sensor, after the operation of the relay the relay is immediately switched off and then switched on again. This will occur in cases where the sensor is located in close proximity to the cooler or heater. Secondly, all sensors and electronic devices have a certain accuracy. For example, you can track the temperature in 1 degree, but smaller values are much more difficult to track. In this case, simple electronics often begin to make mistakes and make mutually exclusive decisions, especially when the temperature is almost the same as that set for triggering.

Process of creation

If we talk about how to make a thermoregulator with our own hands, then it should be said that the sensor here is a thermistor that reduces its resistance during heating. It is included in the voltage divider circuit. A variable resistor R2 is also included in the circuit , through which the operating temperature is set. From the divider, the voltage goes to the 2N-HE element, which is turned on in the inverter mode, and then to the base of the transistor serving as an arrester for capacitor C1. It, in turn, is connected to the input (S) of the RS-flip-flop, which is assembled on a pair of elements, as well as to the input of another 2N-HE. From the divider, the voltage is applied to the 2N-N input, which controls the second input (R) of the RS-flip-flop.

How it works

So, we are considering how to create a simple thermoregulator yourself, so it's important to understand how it works in different situations. At high temperature, the thermistors are characterized by a low voltage, so the divider has a voltage perceived by the logic circuits as zero. The transistor is open at the same time, a logic zero is sensed at the input of the S-flip-flop, and the capacitor C1 is discharged. A logical unit is set at the output of the trigger. The relay is in the ON mode, and the transistor VT2 is open. In order to understand exactly how to make a temperature regulator, it is worth noting that this particular implementation of the relay is focused on cooling the object, that is, it turns on the fan at high temperature.

Lowering of temperature

When the temperature decreases, the resistance increases in the thermistor, which leads to an increase in the voltage at the divider. At a certain moment, the transistor VT1 closes, after which the capacitor C1 starts charging through R5. In the end, the time has come to reach the level of a logical unit. It comes to one of the inputs D4, and the second input of this element is supplied voltage from the divider. When logical units are set on both inputs, and zero appears at the output of the element, the trigger switches to the opposite state. In this case, the relay will be turned off, which will turn off the fan if necessary, or turn on the heating. So you can make a thermoregulator for the cellar with your own hands, so that it turns on and off the fan if necessary.

Increase in temperature

So, the temperature began to increase again. Zero on the divider will appear first on one of the inputs of D4, it will remove zero at the input of the trigger, changing it by one. Then, as the temperature increases, zero will appear on the inverter. After it is changed to one, a transistor will be opened, which will result in the discharge of the C1 element and the setting of zero at the input of the trigger that cuts the heating of the coolant in the water heating system or turns on the fan. Such thermostats for heating, made by their own hands, work quite efficiently.

The blocks C1, R5 and VT1 are designed to eliminate the auto-generation due to the fact that they set the delay time for the shutdown. It can be from a few seconds to several minutes. We are considering a fairly simple thermoregulator, created by ourselves, so the above-mentioned node also allows to eliminate the bounce of the temperature sensor. Even with very small very first pulse, the transistor is opened and the capacitor is instantly discharged. Then the bounce will be ignored. When the transistor is closed, the situation repeats. Charging of the capacitor begins only after the completion of the last bounce pulse. Due to the introduction of the trigger into the circuit, it is possible to ensure the maximum accuracy of the relay operation. As is known, the trigger can have only two positions.

Assembly

To make the thermoregulator with your own hands, you can use a special mounting plate, on which the whole circuit will be assembled by a hinged method. You can also use a printed circuit board. Power can be used anywhere within 3-15 volts. The relay should be selected in accordance with this.

In a similar scheme, you can make a thermoregulator for an aquarium with your own hands, but you should consider that it must be attached to the outside of the glass, then there will be no problems with its use.

The relay described above demonstrated a very high reliability during operation. The temperature is maintained to within a fraction of a degree. However, it is directly dependent on the time delay determined by the R5C1 circuit, as well as the response to the triggering, that is, the power of the cooler or heater. The temperature range and the accuracy of its installation are determined by the selection of the divider resistors. If you made such a thermoregulator with your own hands, then it does not need tuning, but it starts working immediately.