Connecting a temperature sensor - types, design, principle of operation and step-by-step do-it-yourself installation diagram

Currently, every living space must have a heating system. Heating occurs due to the combustion of some fuel, and this incurs certain costs. A responsible homeowner strives to reduce any excess energy consumption to a minimum or eliminate it altogether.

There is a solution for heating systems that helps avoid unnecessary costs. This becomes possible by connecting temperature sensors to the heating system, which can be seen in the photo.

But if you select and connect the device incorrectly, a situation of even greater overspending arises. In this material we will look at how to prevent this.

Sensor structure and operation

The temperature sensor measures pressure, expansion, resistance, which are dependent on the temperature within a certain range. If the thermostat is automatic, then all the formulas are included in the working program.

The device is simple, consists of a small case with fasteners, and a sensor is built inside. It can be sealed or open, with or without wires.

Basically, the device contains a temperature-sensitive liquid or metal. When heating occurs, the liquid begins to expand, and metal parts create resistance. All information goes to the automation system, where the boiler combustion is adjusted. The thermostat, turning the boiler on and off, creates its operating mode.

Types of smoke detectors

The detector sensor detects even small smoke

Room analysis smoke detectors are the most popular means of detecting fire signs known. Every combustion process (paper, textiles, electrical equipment, etc.) is accompanied by the formation of smoke. Such devices are capable of notifying people about a fire in the early stages of its development, when their life and health, as well as property, are not in danger. For this reason, this type of sensors can be found in apartments, public buildings, and warehouses.

Operating principle: The functioning of the smoke analyzer is based on the dispersion of the light flux through smoke microparticles. The luminous flux is created using an LED that operates in the infrared range. If there is smoke in the protected area, some part of the photon flux is reflected from smoke particles, about which information is sent to the receiver. The built-in microprocessor analyzes the received data, after which it switches the detector to the “Alarm” position.

For different positions of emitters and receivers, smoke sensors can be linear or point. The name of devices of this type begins with “IP 212”, which stands for “fire detector”, by the number 2 (two) we mean the “smoke sensor” model, and “12” means the principle of operation, i.e. "optics".

Point detectors

In such a device of this type, the photodetector and the light flux generator are placed on both sides of the smoke reception chamber and are enclosed in one housing. The sensor has perforations on the lid, allowing smoke particles to easily penetrate inside. Based on this, we can conclude that the optical-electronic fire smoke detector analyzes the level of smoke in the protected area of ​​the building at a specific point. The advantage of smoke analyzers is their compact housing, ease of installation and cleaning, and effective smoke detection. Point detectors are mounted on the ceiling at a certain distance, which is calculated according to the height of the ceilings in the room. In some cases, placement on walls and other structural elements of buildings and structures is allowed.

The simplified diagram shows that when smoke appears, part of the radiation is reflected from it and hits the photocell

Grouping of temperature sensors

When choosing a device, you need to decide where it will stand and monitor the temperature. This could be inside the boiler, in the heating system or in the room.

The correct operation of the heating system will depend on the choice.

Temperature sensors can be divided into several categories:

• By temperature determination method;
• By the way the interaction with the thermostat occurs;
• According to accommodation options.

Connecting LMT01 to MSP430

Rice. 19. Connection diagram of LMT01 to MSP430G2553

Rice. 20. Connecting LMT01 to Launchpad MSP-EXP430G2

Launchpad MSP-EXP430G2 debugging board is shown in Figure 19. For connection, an option with an internal comparator was used, pulses were counted using a timer. All this significantly simplifies both the connection diagram and the program code. The layout of the device is shown in Figure 20 (in the photo, power is supplied to LMT01 from P2.4, but in the attached example line P1.6 is used for this). The program has many comments in Russian and will be understandable even to a novice developer. The temperature value and “raw” data (number of pulses) are output to the UART at a speed of 9600 bps. The result of the program is shown in Figure 21.

Rice. 21. Temperature measurement with LMT01

In the archive you can find the program code for working LMT01 together with MSP430G2553.

Types of temperature-detecting devices

There are several categories of sensors that indicate the temperature of the heating system:

• Dilatometric in the form of a spiral or bimetal plate, they work on the principle of expansion of metal elements;
• Resistive, depend on changes in electrical resistance, responding to all temperature changes in a specific interval;
• Thermoelectric ones are made of alumel-chromel; at certain temperature conditions, a thermocouple is activated;
• Gauge gauges react to changes in liquid or gas pressure in a confined space.

How to connect the power connector of the central unit with six contacts?

1. The red wire is the plus of the 12 Volt power supply. The wiring connection must be made to the place with the positive terminal of the battery.
2. The yellow wire is the output to ignition supply Number 1. It must be connected to the place where the ignition terminal is located (IGN1; 15 to 1). Ignition control, inlet.
3. The green wire is the accessory activation control output. It must be connected to ACC (Accessories terminal), located in the ignition switch.
4. The blue wire is an additional control input hole. The blue wire must be connected to the correct terminal located in the ignition switch. The terminal is selected in relation to the output functioning algorithm or to the brake pedal for cars that have a start button. When it becomes necessary to measure polarity, an auxiliary relay should be used.
5. The black and yellow wire is the input channel for manipulating the starter blocking function when activating the starter's security and protective modes.

Source

Types of sensors for contact with the thermostat

Sensors that measure temperature interact with a device that maintains the temperature in one mode. These meters can be divided into two types:

• Wired, when the temperature sensor is connected to the boiler using wires;
• Wireless operate by transmitting information via radio frequencies.

Sensor DS18B20: construction diagram

The DS18B20 device has 3 key housings:

1. TO-92 side;
2. Wall SO-150mil;
3. uSOP housing.

If we talk about the internal structure, then we should consider a small microcircuit, which is shown in the figure:

This microcircuit indicates the presence of several key modular blocks in the structure of the DS18B20, which are responsible for the mechanism for the correct operation of the device.

So, it’s worth starting with the “POWER SUPPLY SENSE” block; it provides complete power for the functioning of the entire system. The assistant of “POWER SUPPLY SENSE” is the nurse “PARASIT POWER CIRCUIT”, who is capable, if necessary, of taking on the function of a food manager.

Another key element in the structure of the temperature sensor should be “64-BITROM AND 1-WIREPORT”. This is a structure module responsible for storing a unique device code and transferring this code to the internal memory of the DS18B20 “SCRATCHPAD”. “SCRATCHPAD”, in turn, interacting with the “MEMORY CONTROL LOGIC” and “1-Wire” registers, supplies a communication signal to the following fundamentally important sensor blocks:

• “TEMPERATURE SENSOR” (a system designed to read converted temperature indicators);
• "CONFIGURATON REGISTER" (the structure responsible for setting the unique programmable precision, which varies from 9 bits to 12 or, if we consider degrees Celsius, from 0.5 °C to 0.0625 °C.);
• “8-BIT CRC GENERATOR” (a system designed purely for a protective function);
• “ALARM HIGH TRIGGER” (block that limits the lower temperature limits DS18B20);
• "ALARM LOW TRIGGER" (system that limits the upper temperature limits DS18B20).

Accommodation options

Thermal sensors can be installed in different places; they can also be divided into several groups:

• Overlays are attached tightly to the surface, which is heated;
• Submersible units are installed directly with the coolant;
• Room ones that measure ambient temperature;
• External, used for installation outside the premises.

Installation on the engine

Making a sensor for an alarm with your own hands is still half the battle. You need to install it correctly and connect it to the system. In order for the thermistor to show the engine temperature as accurately as possible, the best place for it is the cylinder block.

The latter cools down later than all other parts, so the signal to turn on the starter will arrive in a timely manner. With a different arrangement, the system mistakenly believes that the engine has already cooled down and will start it more often, which leads to excessive fuel consumption.

The easiest way to mount your sensor is on the thermostat or radiator pipe. In the first case, it will show a more realistic temperature, in the second, it will be easier to connect in parallel with the hood closing sensor. The fastening method is the same:

• attach the homemade thermistor to the metal surface of the pipe;
• secure it with electrical tape;
• insulate the outside with heat-insulating material and fix it with the same electrical tape.

The proprietary sensor should be installed on any metal part of the engine (cylinder block, cylinder head, valve box cover) where there is a protruding pin with an M6 thread. If there are none, you can make a transition piece and secure it into the blind threaded hole of the eye bolt.

Connecting a temperature sensor

Whatever type of temperature meters they are connected to a thermostat or other control controller. Before operation, you should read the user manual to become familiar with the parameters and requirements needed to install the device.

Experts advise choosing sensors recommended by the manufacturer.

Addressable fire alarm sensors.

So, there are definitely fewer addressable fire detectors needed than non-addressable ones. There may be two indoors, or maybe one, instead of three non-addressed ones.

Recently, in projects you can see one addressable sensor in a room.

The most interesting thing is that you can’t guess in advance whether one addressable fire detector will roll into the room or not. More likely no than yes. So it’s better to put two at once.

Addressable sensors are a great salvation at sites where floor beams are more than 0.4 m and there are many of them.

Or large halls, when a double number of sensors need to be placed along only two walls of the protected space.

And in general, an addressable system has all the advantages over a non-addressable one, except for the price and requirements for the qualifications of installers.

And that's not always the case.

Connecting an outdoor device

The connection diagram for an outdoor temperature sensor is simple, but requires certain conditions to be met:

• The sun's rays should not fall on the device;
• A non-metallic wall surface for fastening is required;
• The sensor is hung at a height of 2/3 of the building level;
• For accurate operation without interruptions, it is necessary to exclude the effect of aggressive environments and negative factors on the device;
• Do not lay the cable in damp places.

When running a cable along the street, it is necessary to place the wire in a corrugation. When connecting parts, care must be taken; work must be done with the power supply to the equipment turned off.

How to choose?

When choosing a temperature sensor, you must be guided by the following criteria:

• if the sensor is in contact with or located inside the measured medium, then a contact model is taken, if it is located outside the object, then a non-contact model;
• the conditions and state of the environment in which it will operate (humidity, aggressive substances, etc.) must correspond to the capabilities of the sensor;
• the step and calibration of measurements should ensure convenient operation of both the sensor and the equipment;
• if the sensor must be replaced during operation, then replacement options are installed;
• when choosing a temperature sensor to replace a faulty one, it is better to use its VIN code;
• The operating temperature limit must cover all possible heating values, some of which are shown in the table below.

Table: temperature limits of thermoelectric type sensors

Connecting the sensor indoors

To measure room temperature, the meter is mounted on the inside of the building.

The location is selected according to the following parameters:

• There was free access to the sensor;
• There were no devices that produced heat or cold;
• It was at a height of one and a half meters from the floor;
• There were no powerful electrical devices emitting electromagnetic waves nearby.

The sensor can be mounted on a wall or in a recess, but it must be open from the outside.

Checking the coolant level

Many car owners often check the coolant level visually without using special instruments. You just need to look at the expansion tank.

If the engine is cold, the coolant should be between the maximum and minimum marks on the reservoir. When the engine is warm, the level of the substance may increase slightly.

If your car is in full working order, then when the antifreeze level decreases, the sensor immediately lets you know about it. The driver sees a special signal on the dashboard and adds antifreeze or coolant.

It is also contraindicated to add water alone. After all, antifreeze has special properties that protect cylinder heads from corrosion.

If checking the coolant temperature sensor does not show the coolant temperature. In this case, you better contact technical service.

In any car, everything is interconnected. The car system could fail for some related reason. For example, you could remove some part located with the sensor and place it incorrectly.

But it also happens that the problem is related specifically to the temperature sensor. The coolant level may be inconsistent or there may be a problem with the coolant level sensor.

The service can replace the sensor, and they provide a guarantee for its high-quality replacement and the correct assembly of all parts in the right places.

Thus, the coolant temperature sensor is a very important component of your car, which requires constant attention and care.

If repair of this device is necessary, then do it efficiently, without regretting the money spent. After repair, the engine will run smoothly, this will be especially noticeable at low speeds.

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Why is a boiler sensor needed?

Modern heating equipment is equipped with elements that contribute to the efficient use of energy resources:

• Electric heaters are designed to produce infrared radiation with high efficiency;
• In gas heating boilers, a system for regular flame monitoring is built in, optimizing the entire process;
• Boilers with solid fuels have various chambers built into them where processed products are removed.

If there is no correct heat flow, optimal use of fuel and electricity will not be beneficial. This will require some conditions for creating individual components. This is where a temperature regulator becomes necessary.

Proper use of equipment produces such positive aspects as:

• Autonomous temperature maintenance mode;
• Saving heating costs up to 30 percent;
• It is possible to remotely adjust modes;
• The service life of the boiler is extended.

Adviсe:

1. Before buying a boiler, you should measure the room and calculate the required air temperature, so that there is no downtime due to modifications to the heating system.
2. It is necessary to insulate a house or apartment before installing equipment to avoid heat losses.
3. To begin with, you can buy an inexpensive sensor, test it in operation, maybe it will work great.

Temperature meters are easy to select and install. The main thing is to follow the proposed instructions and carry out all the steps in the work step by step.

Connecting LMT01 to ATiny25

Rice. 13. Layout and connection diagram of LMT01 to the ATiny25 microcontroller

Photo of temperature sensor connection