Homemade light sensor on a car. Light sensor in a car: what is it? How does a light sensor work in a car? Then connect the laser pointer to the power supply
This article will discuss the scheme and step by step assembly light sensor, which can be useful in everyday life or household. The light sensor circuit is very simple, there is a printed circuit board and a detailed description.
The light sensor can be useful, for example, to control lighting in a closed greenhouse, when you need to automatically turn the light on or off, focusing on the time of day. For example, if it is night outside, then the light will not burn in the greenhouse, if it is day outside, then the light turns on accordingly.
This device registers the intensity of sunlight falling on it. When there will be a lot of light, i.e. the sun will rise, a log will be set at the output. 1. When the day comes to an end, the sun will go below the horizon, the output will be a log. 0, the lights will turn off until the next morning. In general, the scope of the light sensor is very wide and is limited only by the imagination of the person who assembled it. Often, such sensors are used to illuminate the cabinet when the door is opened.
Light sensor circuit
The key link in the circuit is the photoresistor (R4). The more light hits it, the more its resistance decreases. You can use any photoresistor that you can find, because this is a rather scarce part. Imported photoresistors are compact, but sometimes they cost quite a lot. Examples of imported photoresistors - VT93N1, GL5516. You can also apply domestic ones, for example, FSD-1, SF2-1. They cost much less, but will also work well in this scheme.
If it was not possible to get a photoresistor, but you really want to make a light sensor, then you can proceed as follows. Take an old, preferably germanium transistor in a round metal case and cut off its top, thereby exposing the transistor crystal. The photo below shows just such a transistor with a sawn off cover.
It is very important not to damage the crystal itself by tearing off the cover. Almost any transistors in such a round case will do, Soviet germanium ones, for example, MP16, MP101, MP14, P29, P27, will work especially well. Because now the crystal of such a "modified" transistor is open, the resistance K-E transition will depend on the intensity of the light hitting the crystal. Instead of a photoresistor, the collector and emitter of the transistor are soldered, the base output simply bites off.
The circuit uses an operational amplifier, you can use any single, suitable for the pinout. For example, widely available TL071, TL081. The transistor in the circuit is any low-power NPN structure, BC547, KT3102, KT503 are suitable. It switches the load, which can serve as a relay or a small segment led strip, For example. It is desirable to connect a powerful load using a relay, the diode D1 is in the circuit for damping the self-induction pulses of the relay winding. The load is connected to the output marked OUT. The supply voltage of the circuit is 12 volts.
The value of the trimmer resistor in this circuit depends on the choice of photoresistor. If the photoresistor has an average resistance, for example, 50 kOhm, then the tuning resistor should have two to three times more resistance, i.e. 100-150 kOhm. My photoresistor SFD-1 has a resistance of more than 2 MΩ, so I took a trimmer for 5 MΩ. There are also lower resistance photoresistors.
Assembling the light sensor
So, let's move from words to deeds - first of all, you need to make a printed circuit board. There is a LUT method for this, which I use.
The file with the printed circuit board is attached to the article, you do not need to mirror it before printing.
Download PCB:
Download light sensor circuit board
Light sensors today are quite common. In terms of their design parameters, they differ greatly. First of all, this is due to the fact that there are a lot of photocells on the market. However, there are many models with different types adapters. However, in order to understand this issue in more detail, you should study the structure of these devices. Only after that it will be possible to proceed directly to the assembly of the sensor for light.
Classic device diagram
The most standard sensor circuit for light includes a photocell. In this case, adapters are often used non-linear. However, linear modifications are also in demand today. Even in the circuit of a standard light sensor there are capacitors of various capacities. They can be arranged in serial or parallel order. Directly for lamps, cartridges of different diameters are installed. Board systems are most often of the multi-channel type.
Model with magnetic photocell
With a magnetic photocell, the light sensor (diagram shown below) is most suitable for enclosed spaces. At the same time, the model can be used outdoors only at positive temperatures. In order to assemble the light sensor with your own hands, it is more expedient to use a lamp for 5 V. In this case, the cartridge can be purchased separately for the device in the store. The next step is to deal directly with the installation of the photocell.
The case for these purposes must be used plastic. After installing the photocell for signal transmission, a cardioid conductor is mounted. The capacitance of this element should not exceed 3 pF. Otherwise, the incandescent lamp may not withstand a large load. Direct connection to the 220 V network is carried out in the first phase. To do this, it is necessary to close only the upper contacts. The conductor in this case can be used with the marking PP20.
Application of broadband photocells
This type of light sensor is not easy to assemble. First of all, you need to find a good photocell. To install it, you need a solid case. Additionally, it should be noted that it must be sealed, since the above photocell does not tolerate high humidity. It is also not recommended to use it at sub-zero temperatures. However, indoors, he is able to do a good job. Capacitors for it are most often used integral. They differ in capacity. In this case, much depends on the selected incandescent lamp.
If we consider the 5 V option, then capacitors in this situation can be used at 15 pF. In this case, the connection of the light sensor to the network must be carried out through an adapter. Control boards are often used to adjust the power of the device. Today, multi-channel models are in great demand. In order to connect the light switch sensor to a 220 V network, an auxiliary adapter is indispensable.
Dipole sensor
On dipole resistors, a light sensor for lighting is widespread. Photocells in models are installed mainly of the spectral type. For the street, this option is ideal. It can be used effectively even at a temperature of -20 degrees. In this case, the closure of the resistors will not occur. In this case, only one capacitor is required for installation. It must be selected open or closed type. However, the capacitance of the capacitor should not exceed 5 pF.
Amplifiers in such a device are used quite rarely. It is much better to install conventional controllers for control. Contact systems for connection are selected single-phase. However, in this situation, you must first look at the switchboard. Only after that it will be possible to decide on the adapter so that the bulb does not burn out.
Wave capacitor sensor
This type of light sensor can be assembled if you prepare a magnetic photocell. Diode resistors are most suitable for the model, and their capacitance must be at least 30 pF. Sensors of this type differ significantly in sensitivity. Amplifiers are installed with medium power. Modulators for the device are more suitable for the integral type. In this case, the sensitivity parameter will be at the level of 22 microns. It should also be noted that the diffuser in this case can be connected directly through the power supply.
Use of selective capacitors
This type of light sensor is highly sensitive. These devices are not suitable for the street. However, much depends on the type of photocell. If we consider integral modifications, then they are not afraid of high humidity. They are also insensitive to sub-zero temperatures, and the devices can be used in cold weather. Resistors are most often installed in an open type.
At the same time, a wide variety of management boards are suitable. In order to independently assemble the model, it is more expedient to select adapters with auxiliary adapters. The light sensor is connected via the first phase. In this case, the contacts must be fixed first of all from above. In order to check the grounding, you need to use a tester.
Ultra sensitive sensors for light
An ultra-sensitive light sensor for closed rooms is well suited. Most often, models are installed in office buildings. Thus, you can save quite a lot on electricity. In order to independently fold the ultra-sensitive modification, it is better to purchase a magnetic type photocell. It is more expedient to select resistors with a high conductivity parameter.
In this case, the adapter can be used the simplest. In this case, amplifiers, as a rule, are not used. An accessory adapter is required to connect the sensor. As a rule, it is used for two contacts. To make system failures as rare as possible, many experts recommend using resistance modules. You can usually find them in the store marked 10 ohms.
Modifications with reduced sensitivity
This type of light sensor is specially designed for use in harsh weather conditions. On average, models are able to withstand temperatures up to -20 degrees. Their photocells are installed exclusively integral. They differ in that they are practically not afraid of high humidity. At the same time, they can withstand small mechanical damage.
You can't say the same about magnetic analogues. In order to independently assemble a light sensor (street), you will need a high-capacity capacitor. Additionally, low-power resistors are used for stable operation. Controllers for the sensor can be installed in a variety of ways.
Modifications with a membrane amplifier
Assembling a sensor with a membrane amplifier can be quite simple. If we consider the most simple modification, then it is more expedient to select a lamp for 5 V. In this case, the cartridge should be 4.5 cm in diameter. After fixing the photocell, it is necessary to fix the resistor. If we consider a model without a control board, then the amplifier should be installed near the output switch. In this case, the connection must be made through an adapter with insulation.
If we consider a model with a control board, then first of all it is important to solder an auxiliary adapter to the photocell using a blowtorch. Only after that a switch with contacts is connected to the system. The conductors in this case must be brought to the side and insulated to exclude cases of short circuits.
The top configurations of currently sold cars have a large selection of various electronic options in their arsenal. All of them are aimed at making driving safer and more comfortable. Not to say that most of them are not replaceable, but sometimes they can still make our everyday driving easier. So all kinds of rain and light sensors are able to automatically turn on the wipers or the head light on the car. The light sensor, which we want to talk about in more detail, can help the driver when driving through tunnels or when it gets dark and it's time to turn on the light. According to the principle of operation, such a sensor is triggered when conditions of insufficient illumination occur. If you have a desire to implement a similar function in your car, then we will tell you how to do it.
Light sensor diagram for a car
Of course, the control element in the circuit is a photoresistor, that is, a radio component that changes its resistance depending on the illumination. The circuit also includes the NE555 meter, which in this case is used a little differently from the classical application. But the power block of the circuit is implemented on a transistor and a relay, which ultimately switches the power to turn on the headlights. And now about this all in more detail. So let's take a look at the diagram...
In fact, the NE555 generates a logical zero or one at its output, pin 3. It depends on what is fed to the input of the microcircuit, pin 4. As soon as the voltage reaches a certain level at the input, a logical one appears at the output. You ask why it was impossible to use a transistor instead of a microcircuit and send a signal to its base? Everything is simple here! Digital logic, or rather, the output from the microcircuit changes immediately and for the entire value, that is, it is not an analog element. And in the end, the operation of the entire scheme will be clear. It worked or it didn't work, without possible signal build-up and unstable operation. It is these advantages that still force the use of a microcircuit here. Further, from the output of the microcircuit (leg 3), the signal is already sent to the transistor. In fact, coupled with a relay, this is the power part of the circuit. As soon as the transistor opens from the potential at the base, current begins to flow through the emitter-collector. It is he who causes the relay to work. Of course, the relay turns on the headlights. If we talk about the features of the circuit, then attention should be paid to the photoresistor, because the resistance will depend on it, and hence the response threshold of the entire circuit. In our case, this is a 5516 photoresistor with a minimum resistance of about 1500 ohms. In series with the photoresistor, you can put a trimmer resistor, say 1 kOhm. However, the scheme works in a comfortable range of illumination for the eyes, as it seems to us. Also, for economy, it is worth setting the maximum possible resistance value for the resistor from leg 3 to the base of the transistor. If you have time, then play around with this resistor in order to protect the chip from high currents passing through it and reduce the power consumption of the entire circuit.
As for the LED and the resistance, it's actually a visual indicator that the headlights have been turned on by your light sensor. In addition, the LED helps to smooth out the inductive current on the relay, thereby saving both the relay coil and the transistor from it.
How to connect a light sensor on a car
Now a few words about the connection. The photoresistor must be installed on the instrument panel under the base of the windshield. That is, where the direct Sun rays can hit him. It is better to connect the circuit itself in parallel with the switch that turns on the headlights or fog lights. That is, the relay contacts must switch the light on parallel to the steering column switch. If you want to turn off the operation of the light sensor, then you can put another toggle switch to power this circuit. Then at any time and easily you can simply turn off such a light sensor.
Summarizing…
As you can see, the scheme is quite simple and clear. Its reliability is also very high. If everything is mounted correctly and without errors, then the configuration will not be needed at all or will be minimal. Well, at the expense of functionality, we have already spoken. This is quite a viable option, as you can add the “light sensor” option to a car.
DIY light sensor video
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D but there will be light, once said a famous movie character and his words became a prophecy for our time. Now lighting is everywhere, and the main concern of every owner country house is to optimize the cost of providing convenience, which provides lighting of the area near the house. This can be done using a light sensor for street lighting. This small device can not only organize the autonomy of the lighting system, but also save the family budget well. It can be purchased ready-made or made with your own hands, in any case, it is worth learning more about it.
A light sensor will help optimize the cost of lighting the local area
What is a light sensor for street lighting, what are they, where are they used?
Most often, such a sensor is installed for street lighting by owners. country houses. This step is logical, because there is no need to constantly leave the light on. And if the yard is large, then while you manage to get to the switch, you can fall 10 times, especially in winter, in ice, in which case the sensor will become a real magician and helper. In addition, this device is able not only to save money, but also to extend the life of lamps and other lighting equipment.
The main types of light sensors are:
- Those that react to the level of illumination. As soon as dusk sets in, they turn on the lights, with the advent of dawn they turn off.
- Motion sensors. Its principle of operation lies in the characteristics of the radiation that is released human body. So in the daytime it is not perceptible, but at dusk and in the dark, infrared radiation tells the sensor to turn on the lights. That is, it captures the infrared range that each of us emits.
- Combined. They have a special timer that can be programmed to turn on and off. That is, after the light is turned on with it, after a certain set time, it will turn off.
In private homes, the second or third type is most often used. Since there is no need for constant lighting at night, and the first one is in demand for use in entrances in apartment buildings or other public places. For example, for lighting streets or highways.
How to connect a light sensor for street lighting?
In the process of building a house, it is worth providing a wire outlet for connecting street lighting, if this is not done, then first you need to make a suitable wire outlet. Only then can the sensor be connected. It is necessary to organize two free contacts in the switchboard, if there are parking spaces on the territory, it should be illuminated using a separate line. The connection diagram looks like this:
It has a break in the phase cable that goes to the lamp. But it is worth paying attention to one difference. In order for the device to work, there must be a neutral wire. Simple zero is not carried out, the ends of the wires are stripped and hidden in the junction box. To avoid getting moisture and dust on the cables, they should be wound from below. For this, rubber seals are used, they are most often included in the kit. The photocell of the sensor can be located either side by side or in a separate block.
There is also a threshold element. It compares the amount of light and the level of illumination that enter the photocell. Available in it, provides lighting on and off. When mounting the sensor, you should pay attention so that the light of the flashlight that you connect to it does not fall on it. And it turns out that as soon as darkness comes, the sensor will turn on the light, and it will fall on it and turn off again and so on in a circle until one of them gives up.
It is important to determine the correct placement of the device, and for this, take into account the following points:
- He must be in disguise.
- The sensor must not be exposed to electromagnetic radiation, which may affect its correct operation.
- The temperature should not affect, it can disable the device.
- It should be placed at a height of at least 1 meter from the ground, this will prevent it from reacting to pets.
The sensor will last longer if carried out regularly. Maintenance and take good care of him.
Related article:
Do-it-yourself light sensors for street lighting are not difficult to make, especially if you have at least minimal knowledge in electrical engineering. The sensor circuit consists of simple and affordable elements that are easy to assemble on your own.
The main component of the device is a phototransistor, it is responsible for converting the light flux into electricity. It has a higher sensitivity when compared with a photodiode or resistor. If it is not possible to find one, then one of the common transistors can be used. For these purposes, the MP series, for example, MP37, is suitable. To turn it into a phototransistor, it is enough to grind off the upper part of it with sandpaper.
In addition, you will need to purchase a power supply, a relay and a tuning resistor. All this must be assembled according to the scheme indicated above. But most often, such an assembly with your own hands is impractical for a number of reasons:
- Buying and searching for items will pull a lot cash and take time.
- The cost of a kit above these components will probably be more expensive than a finished device, so think about whether it is worth spending money.
conclusions
A light sensor for a country house is a profitable and convenient device. You can assemble it yourself or buy it ready-made, and then connect it according to a suitable scheme. With such a connection, it is important to take into account the points that may affect its quality work.
The creation of a sensor that reacts to light was described and examples of control schemes were given. powerful electric motor and LED. It would be more useful to control some kind of powerful load, for example: an incandescent lamp, a powerful electric motor, etc. simple circuit a photorelay for a powerful load is shown in Figure 1:
Figure 1 - Photorelay triggered by a decrease in illumination
without sensitivity adjustment
This circuit uses an electromagnetic contact relay. The simplest and cheapest accessible way control of a powerful load is the use of an electromagnetic contact relay:
The relay shown in the photo above was taken from a broken imported refrigerator, this relay can switch (connect and disconnect in this case) a load that consumes no more than 16A. 16A is enough for many household electrical appliances. On the body of this relay it is written that for the coil direct current 12 V is needed, but in practice, 9V from the power supply for the modem with a rectifier was enough to trigger this relay:
If 9V is not enough, then you can power the circuit from 12V. If you replace the resistor R1 with a variable or trimmer, then you can adjust the sensitivity to light.
The reverse current of this photodiode is amplified by the transistor VT1:
This transistor forms a voltage divider together with resistor R1:
As mentioned above, this resistor can be replaced with a variable or trimmer in order to be able to adjust the sensitivity of the circuit.
The relay coil is directly controlled by the transistor VT2:
KT973 is well suited for this purpose. The relay is connected to the collector of this transistor.
In order for the transistor VT2 not to burn out when it is closed abruptly, a reverse diode is placed in parallel with the relay coil:
This diode can be replaced by any other suitable diode.
Resistor R2 is optional but can be supplied to limit the current or reduce its consumption.
For the power part of the circuit, connectors and wires are needed:
The relay can connect the load to the 220V network. Do not forget that the mains voltage is dangerous and when working with it, precautions must be taken in order not to get an electric shock.
After preparing all necessary details you can start assembling the relay.
It is better to solder the reverse diode directly to the relay.
It is possible to connect a load with a power source to the assembled relay (not necessarily a 220V network). Using this photorelay paired with an infrared radiation source, you can make a presence sensor:
Figure 2 - Scheme including the load with increasing lighting
If the photorelay turns on the incandescent lamp when the illumination decreases, then it is necessary to somehow close the photodiode from the light of the incandescent lamp, otherwise, when the illumination decreases, the relay will often turn on and off, which will lead to its rapid wear and failure. If an infrared photodiode is used, the photorelay will not respond to the light of a fluorescent lamp (unless it is brought close enough), or led lamp(if it does not have infrared LEDs with the corresponding long wavelength of light emitted). It is better not to test the IR control panel on this photocell:
