Photo relay circuits for lighting control. Do-it-yourself photo relay for lighting the local area Simple do-it-yourself photo relay

It would seem like a simple thing to do - turn on and off the street lighting in the yard and in front of the house in time. And it’s not even about saving electricity, although most people living in their own homes are not even aware of how much electricity “flies down the drain” due to an untimely pressed switch button. In the evening, especially in winter, it is much more pleasant to return home in complete darkness and see the threshold of your own home, thanks to the timely switching on of street lighting.

How to spend money on a photo relay for street lighting

To organize automatic switching on of light bulbs, the easiest way is to connect a photo relay for street lighting in one of three ways:

• Buy a set of industrial photo relays, install it yourself or with the help of a familiar specialist, configure and use it as you see fit;
• The most reliable connection diagram for a photo relay for street lighting will be made by a familiar electronics engineer or a person capable of making and installing such a device with his own hands;
• To make a photo relay on your own, fortunately, there are always plenty of parts and circuits for organizing automatic street lighting in the markets.

Advice! You can simply buy a ready-made homemade photo relay board on the radio market, but it’s difficult to say how long such a miracle of technology will work.

DIY photo relay circuit options

It’s easier, of course, to buy a ready-made photo relay circuit. Most Chinese and domestic photo machines are quite easy to use and cost relatively little money.

How to correctly connect a ready-made photo relay circuit to street lighting

The simplest option would be to purchase a ready-made photo relay board. If it is not important for you that the automatic device has any additional service functions, you can install the simplest model of the St. Petersburg manufacturer Megaron, LXP series.

Depending on the number of light bulbs in the street lighting circuit of your home and their total electrical power, you can choose one of the models:

1. The LXP01 board is used for a relatively small-sized street lighting circuit; the total lamp power should not exceed 1200W. The circuit has a built-in photo relay that automatically responds to an illumination level of 6-9 lux, upon reaching which the board will automatically turn the lighting on or off;
2. Model LXP02 can work with twice as many lamps, the total load current should not exceed 10A. In this device, it is already possible to adjust the lighting level with a special regulator - a potentiometer, to which the photo relay will react when the street lighting is turned on or off;
3. Option LXP03 is the most powerful, capable of turning on street lighting even with low-power floodlights and luminaires, economical sodium lamps and similar devices, with a total power consumption of up to 3 kW. The circuit also has the ability to adjust the sensitivity threshold of the photo relay to the light level.

For your information! The above models have typical characteristics corresponding to most designs of photo relays for street lighting of domestic or foreign production offered on the home goods market.

The relay is connected according to the photo relay diagram below.

The box has three terminals indicating connection points. Wires of black, green and red colors, respectively, must be connected to the phase, and the input and output of the street lighting wiring.

The plastic barrel of the photo relay housing itself must be installed in a shaded place on a remote bracket so that snow or rain does not fall on the housing, and tree foliage does not shade or affect the operation of the electronics. In theory, electronics are capable of operating in a temperature range from -25 o C to +40 o C.

From the bottom of the case you can see a tiny rotary potentiometer lever, which is used to adjust the sensitivity of the photo relay. After installation and testing of functionality, the lever is set to the middle position and sequentially, over the course of several days, the illumination level at which it is necessary to turn on the street lighting is selected.

Advice! Extend the short sections of wire coming out of the photo relay housing using an additional three-core cable with wires of the same color.

The connection points must be soldered and insulated with a tubular cambric, electrical tape or another method that provides reliable protection from moisture. The cross-section of each wire core in the cable must be at least 2 mm 2. Lead the cable into the house and connect it to the junction box or directly to the electrical distribution panel. In this case, it is necessary to provide an additional switch on the switchboard that allows you to de-energize, if necessary, the photo relay and the street lighting circuit.

Scheme for photo relay connecting street lighting

If you are a person who has at least minimal knowledge in assembling electronic circuits, or have tried to assemble homemade products, you will probably be able to assemble the simplest and most reliable photo relay circuit using electronic components that cost a penny.

The main advantage of the given version of the photo relay is the maximum simplicity of the design, which largely guarantees the reliable operation of the electronics. The presented photo relay circuit is assembled on a 544 series operational amplifier. The circuit is very simple and easy to manufacture.

At rest, the op amp has a voltage at pin 2 higher than at pin 3. According to the logic of the microcircuit, this means a stable and balanced position; accordingly, control pin 6 will have a low voltage or a logical zero. The low voltage ensures that the KT815 power transistor is kept closed, and the RP21 relay does not switch the power supply to street lighting lamps.

The potential on leg No. 2 is determined by the state of the photoresistor FSK1. Under normal lighting conditions, the photocell has a low resistance, due to which a fairly high potential comes to the 2nd leg. As soon as the light level decreases to a programmable limit, the resistance of the photoresistor increases and the potential on the second leg of the chip decreases. In this situation, the microcircuit operates in accordance with the underlying logic and increases the voltage at control contact No. 6, the key on the KT transistor supplies the necessary voltage to the control winding of the relay, the circuit closes, and the photo relay board turns on the street lighting.

The photo relay device uses a special 1 MΩ tuning resistor, by rotating which you can quite easily set the level of sensitivity of the device to the level of illumination.

Most of the parts can be assembled by air mounting, but it is better to make a board according to the circuit and build a full-fledged photo relay device.

Most parts can be bought for pennies on the market or from TV technicians, or even soldered from the board of old and deteriorating electronics of a power supply or similar devices. If you don’t find a 544 series chip, you can take a 140 series. Instead of the K10-7V capacitor, you can use any imported version with the same voltage and capacity. SP3-38 can be used as a 1M Ohm control resistor.

You can even make a photocell with your own hands from old, very common transistors MP 25 - 41. To make the main part of the photo relay, just carefully cut off the upper plane of the head and seal the cut with a piece of thin transparent plastic. The collector of such a phototransistor will be connected to the second leg of the microcircuit; the emitter, accordingly, is used as the top contact in the circuit. In this case, the control resistance must be reduced to 6.8-7 kOhm.

The disadvantage of the circuit is the need to organize additional external power supply at 12V. For these purposes, you can use a battery or a transformer from a Chinese power supply, fortunately, the photo relay circuit is insensitive to quality and voltage drops.

The board must be placed indoors, and the photocell must be installed in a tubular housing and taken to a place outside that is most suitable for installing the photo relay.

The simplest photo relay option for street lighting

If you couldn’t find some parts for making a photo relay with your own hands, or working with a microcircuit seems too complicated for you, you can build a photo relay for street lighting using literally three transistors and a pair of hanging elements according to the diagram given.

The design of the photo relay is a greatly simplified previous version. It does not contain an operational amplifier chip and allows you to assemble a photo relay using spare parts from an old low-frequency amplifier or a Soviet pocket radio. The cost of manufacturing such a photo relay for street lighting will be an order of magnitude cheaper than the previous option.

The logic of operation of the photorelay circuit is approximately the same as in the previous case, but in this embodiment, a change in the conductivity of the FSK photoresistor opens or closes the key on the MP41 transistor, and then, along the chain, the control winding of the relay is turned on at 12V. The sensitivity of the photocell is adjusted using a 47 kOhm trimming resistor. All circuit elements, except the relay, can be assembled by air mounting, insulated and placed in a box the size of a matchbox.

The power of the circuit is small, it is enough to connect small relays with a switching current of several amperes. This is quite enough to turn on small street lighting with several lamps.

Conclusion

There are many different schemes for street lighting that can not only turn lamps on or off. Some of them can be programmed to turn on different street lights for different times and durations. When choosing an industrial design of a photo relay, pay attention to whether the design has built-in protection against temporary darkening of the photocell, for example, by birds or fallen leaves accidentally falling on the body.

Automation of lighting supply in an apartment, house or street is achieved through the use of photo relays. If configured correctly, it will turn on the light when it gets dark and turn off during daylight hours. Modern devices contain a setting that allows you to set the trigger depending on the light level. They are an integral part of the “smart home” system, taking on a significant part of the responsibilities of the owners. The photo relay circuit first of all contains a resistor that changes the resistance under the influence of light. It is easy to assemble and configure with your own hands.

Operating principle

The connection diagram for a photo relay includes a sensor, an amplifier and a photoconductor PR1 changes resistance under the influence of light. At the same time, the magnitude of the electric current passing through it changes. The signal is amplified by a composite transistor VT1, VT2 (Darlington circuit), and from it goes to the actuator, which is K1.

In the dark, the resistance of the photosensor is several mOhms. Under the influence of light it decreases to several kOhms. In this case, transistors VT1, VT2 open, turning on relay K1, which controls the load circuit through contact K1.1. Diode VD1 does not allow self-induction current to pass when the relay is turned off.

Despite its simplicity, the photo relay circuit is highly sensitive. To set it to the required level, resistor R1 is used.

The supply voltage is selected according to the relay parameters and is 5-15 V. The winding current does not exceed 50 mA. If it is necessary to increase it, more powerful transistors and relays can be used. The sensitivity of the photo relay increases with increasing supply voltage.

Instead of a photoresistor, you can install a photodiode. If a sensor with increased sensitivity is needed, circuits with phototransistors are used. Their use is advisable in order to save electricity, since the minimum response limit of a conventional device is 5 lux, when surrounding objects are still distinguishable. The threshold of 2 lux corresponds to deep twilight, after which darkness sets in 10 minutes later.

It is advisable to use a photo relay even with manual lighting control, since you can forget to turn off the light, and the sensor will “take care” of this on its own. It is easy to install and the price is quite affordable.

Characteristics of photocells

The choice of photo relay is determined by the following factors:

• photocell sensitivity;
• supply voltage;
• switching power;
• external environment.

Sensitivity is characterized as the ratio of the resulting photocurrent to the external light flux and is measured in μA/lm. It depends on frequency (spectral) and light intensity (integral). To control lighting in everyday life, the last characteristic is important, depending on the total luminous flux.

The rated voltage can be found on the device body or in the accompanying document. Foreign-made devices may have different supply voltage standards.

The load on its contacts depends on the power of the lamps to which the photo relay is connected. Lighting photo relay circuits can provide for direct switching of lamps through sensor contacts or through starters when the load is high.

Outdoors, the twilight switch is placed under a sealed transparent cover. It provides protection from moisture and precipitation. When working in cold periods, heating is used.

Factory made models

Previously, the photo relay circuit was assembled by hand. Now this is not necessary, since devices have become cheaper and functionality has expanded. They are used not only for external or internal lighting, but also for controlling plant watering, ventilation systems, etc.

1. Photo relay FR-2

Factory-made models are widely used in automation devices, for example, to control street lighting. You can often see lights burning during the day that you forgot to turn off. With photo sensors, there is no need for manual lighting control.

The industrially manufactured photo relay circuit fr-2 is used for automatic control of street lighting. Relay K1 is also here. The FSK-G1 photoresistor with resistors R4 and R5 are connected to the base of transistor VT1.

Power is supplied from a single-phase 220 V network. When the illumination is low, the resistance of FSK-G1 is large and the signal based on VT1 is not enough to open it. Accordingly, transistor VT2 is also closed. Relay K1 is energized and its operating contacts are closed, keeping the lamps lit.

When the illumination increases to the operating threshold, the resistance of the photoresistor decreases and opens, after which relay K1 turns off, opening the power supply circuit for the lamps.

2. Types of photo relay

The choice of models is large enough so that you can choose the right one:

• with a remote sensor located outside the product body, to which 2 wires are connected;
• Lux 2 - a device with high reliability and quality level;
• photo relay with 12 V power supply and load no higher;
• module with a timer mounted on a DIN rail;
• IEC devices from a domestic manufacturer with high quality and functionality;
• AZ 112 - automatic machine with high sensitivity;
• ABB, LPX are reliable manufacturers of European quality devices.

Methods for connecting a photo relay

Before purchasing a sensor, you need to calculate the power consumed by the lamps and take it with a margin of 20%. With a significant load, the circuit of a street photo relay provides for the additional installation of an electromagnetic starter, the winding of which must be switched on through the contacts of the photo relay, and switch the load with power contacts.

This method is rarely used at home.

Before installation, the supply voltage of ~220 V is checked. The connection is made from a circuit breaker. The photo sensor is installed in such a way that the light from the flashlight does not fall on it.

The device uses terminals to connect wires, which makes installation easier. If they are missing, a junction box is used.

Thanks to the use of microprocessors, the connection diagram of the photo relay with other elements has acquired new functions. A timer and a motion sensor were added to the action algorithm.

It is convenient when the lamps automatically turn on when a person passes along a landing or along a garden path. Moreover, operation occurs only in the dark. Due to the use of a timer, the photo relay does not react to headlights from passing cars.

The simplest connection diagram for a timer with a motion sensor is serial. For expensive models, special programmable circuits have been developed that take into account various operating conditions.

Photo relay for street lighting

To connect the photo relay, the circuit is applied to its body. It can be found in the documentation for the device.

Three wires come out of the device.

1. Neutral conductor - common for lamps and photo relays (red).
2. Phase - connected to the device input (brown).
3. Potential conductor for supplying voltage from the photo relay to the lamps (blue).

The device operates on the principle of phase interruption or phase switching. Color markings may vary from manufacturer to manufacturer. If there is a ground conductor in the network, it is not connected to the device.

In models with a built-in sensor, which is located inside a transparent case, the street lighting operates autonomously. You just need to supply power to it.

Options with remote sensors are used when the electronic content of the photo relay is conveniently placed in the control panel with other devices. Then there is no need for stand-alone installation, power wiring and maintenance at height. The electronic unit is placed indoors, and the sensor is taken outside.

Features of photo relay for street lighting: diagram

When installing a photo relay outdoors, you need to take into account some factors.

1. Availability of supply voltage and matching power of contacts and load.
2. Installation of devices near flammable materials and in an aggressive environment is not allowed.
3. The base of the device is located at the bottom.
4. There should be no moving objects in front of the sensor, such as tree branches.

The wires are connected through an outdoor junction box. It is fixed next to the photo relay.

Selecting a photo relay

1. The ability to adjust the response threshold allows you to adjust the sensitivity of the sensor depending on the time of year or in cloudy weather. The result is energy savings.
2. A minimum of labor costs is required when installing a photo relay with a built-in sensitive element. This does not require any special skills.
3. The timer relay is well programmable for its needs and operation in the set mode. You can set the device to turn off at night. Indication on the device body and push-button control make settings easy.

Conclusion

The use of a photo relay allows you to automatically control the period of lamp switching on. Now there is no longer any need to become a lamplighter. The photo relay circuit, without human intervention, turns on the lights on the streets in the evenings and turns them off in the morning. The devices can control the lighting system, which increases its resource and makes operation easier.

Technological progress is making people's lives more and more comfortable. For this purpose, new devices are being invented that perform actions without the presence and participation of people.

One such device is a simple photo relay. You can buy such a device in a store, but it’s more interesting and economical to make it yourself.

A photo relay can be used to turn lights on or off at different times of the day. For example, when darkness sets in, the device turns on the lighting, and at dawn it turns off. It can also be used at the entrance of an apartment building or on your own country site.

It is widely used with a photo relay, which turns the lighting on and off in autonomous mode. Such a device can be used in a “smart home”. At the same time, using a photo relay you can not only control the lighting, but also open the blinds or ventilate the room. It should be noted that this device can be installed for a home security system.

Let's understand the circuit of a simple photo relay with our own hands

The simplest photo relay circuit consists of two transistors, a photoresistor, a relay, a diode and a variable resistor. Devices of the KT315B type are used, connected according to the circuit of a composite transistor, the load of which is the relay winding. This circuit has a high gain and high input resistance, which allows it to include a photoresistor with high resistance.

With increasing illumination of the photoresistor connected between the collector and the base of the first transistor, this transistor and transistor No. 2 open. As a result of the appearance of current in the collector circuit of the second transistor, the relay will operate, which, with its contacts, depending on its settings, will turn on or off the load.

To protect the circuit from the effects of self-induction EMF when the relay is turned off, a protective diode of type KD522 is included. To adjust the sensitivity of the circuit, a variable transistor with a nominal value of 10 kOhm is connected between the base and emitter of the first transistor.

In addition to installation in residential and utility rooms, walk-through platforms are used. The connection diagram depends on the number of pins to the light system.

The machines are installed in the electrical panel to protect the electrical network from overload and short circuit - this is what it consists of.

Such a photo relay can be powered from a DC voltage source of 5 - 15 V. In this case, with a source voltage of 6 volts, relays of the RES 9 or RES 47 type are used, and with a supply voltage of 12 V, relays RES 15 or RES 49 are used.

To mount the circuit, you can create a special board, if possible a printed circuit board. Then attach relays, transistors, a variable resistor to the board, make holes for the terminals of the circuit elements and make the appropriate connections using mounting wires and.

The circuit can be set up in a shaded room using an incandescent lamp, from which the light flow can be adjusted.

At the required illumination, the circuit's response threshold is selected using a variable resistor. If in the future it is not planned to adjust the response threshold, then instead of a variable one, a constant one is set, the resistance of which corresponds to the value obtained during the adjustment.

Assembly method on a modern device

When using more complex electronic devices, you can assemble a homemade photo relay, which includes only three components. Such a circuit can be assembled on an integrated semiconductor device from TeccorElectronics Q6004LT (quad), which has a built-in dinistor. Such a device has an operating current of 4 A and an operating voltage of 600 V.

The photo relay connection diagram consists of a Q6004LT device, a photoresistor and a conventional resistor. The circuit is powered from a 220 V network. In the presence of light, the photoresistor has a low resistance (several kOhms), and a very low voltage is present at the control electrode of the quad. The quad is closed and no current flows through its load, which can be lighting lamps.

As the illumination decreases, the resistance of the photoresistor will increase, and the voltage pulses arriving at the control electrode will also increase. When the voltage amplitude increases to 40 V, the triac will open, current will flow through the load circuit and the lighting will turn on.

A resistor is used to configure the circuit. The initial value of its resistance is 47 kOhm. The resistance value is selected depending on the required illumination threshold and the type of photoresistor used. The type of photoresistor is not critical. For example, elements of the type SF3-1, FSK-7 or FSK-G1 can be used as a photoresistor.

You don't have to be a master to know... You just need to learn how to correctly identify breakdowns and remember a few simple rules for correcting them.

A modern power supply system provides three-wire wiring from or to an apartment. Taking into account such conditions, and are established.

Using the powerful Q6004LT device allows you to connect a load of up to 500 W to the photo relay, and when using an additional radiator, this power can be increased to 750 W. To further increase the load power of the photo relay, you can use a quad with operating currents of 6, 8, 10 or 15 A.

Thus, the advantage of this scheme, in addition to the small number of parts used, is the absence of the need for a separate power supply and the ability to switch powerful consumers of electrical energy.

Installation of this circuit is not particularly difficult due to the small number of circuit elements. Setting up the circuit consists of determining the desired threshold for the circuit to operate and is carried out in a manner similar to the previous circuit.

conclusions:

1. In various automatic control systems, most often in lighting systems, photo relays are used.
2. There are many different photo relay circuits using photoresistors, photodiodes and phototransistors as sensors.
3. The simplest photo relay circuits, which contain a minimum of parts, can be assembled with your own hands.

Video with an example of assembling a homemade photo relay

Such schemes are called photo relay, most often this is simply turning on the lighting at night. For this purpose, radio amateurs have developed many schemes, here are some of them.

Probably the simplest circuit is shown in Figure 1. The number of parts in it is small, less can be done, and the efficiency, read sensitivity, is quite high.

Setting up the device comes down to setting the threshold voltage so that it turns on already at dusk. In order not to wait for this natural moment, you can illuminate the photodiode in a darkened room with an incandescent lamp turned on through a thyristor power regulator. The same technique is suitable for setting up other photo relay circuits.

It is possible that when the photo relay is triggered, the relay will rattle. You can get rid of this phenomenon by connecting several hundred microfarads in parallel to the coil.

Photo relay on a microcircuit

The specialized one is a phase power regulator, the same as a regular thyristor. A very important and valuable property of such a power regulator is that it is included in the circuit as a two-terminal device, without requiring an additional power wire: just connect it in parallel with the switch and everything already works! Figure 4 shows how a simple photo relay can be built on this chip.

Rice. 3. Microcircuit KR1182PM1

Figure 4. Photo relay circuit on the KR1182PM1 microcircuit

Control pins of the microcircuit 3 and 6. If you connect just a regular single-pole switch between them, then when it closes, the load will be turned off! If it is opened, the load will be connected. By the way, without additional external thyristors or a triac, and even without a radiator, the microcircuit can withstand a load of up to 150W. This is the case if, when the load is turned on, there are no current surges, as with incandescent lamps. An incandescent lamp in this version can be turned on with a power of no more than 75W.

Just connect the switch to these terminals as if to nothing, unless in conjunction with other parts. If you do not pay attention to the phototransistor and the electrolytic capacitor, mentally leaving only the variable resistor R1, then you simply get a phase power regulator: when you move its slide up the circuit, pins 3 and 6 are short-circuited, thereby disconnecting the load, like the contact mentioned above. When moving the engine down the circuit, the power in the load changes from 0...100%. Everything here is clear and simple.

If you connect an electrolytic capacitor to these terminals (we assume that there is no phototransistor in the circuit yet), you will simply have a smooth switching on of the load. How?

The resistance of a discharged capacitor is small, so at first the control pins of microcircuits 3 and 6 are practically short-circuited and the load is turned off. As the capacitor charges, the resistance of the capacitor increases (just remember checking capacitors with an ohmmeter), the voltage across it also increases, and the power in the load gradually increases. The result is a device for smoothly switching on the load. Moreover, the power will be supplied to the load as much as the variable resistor R1 motor is inserted. When the device is disconnected from the network, the capacitor is discharged through resistor R1, preparing the device for the next turn on. If the capacitor does not have time to discharge, then there will be no smooth switching on.

Now we’ve gotten to the most important thing, the photo relay. If you now connect a phototransistor to control pins 3 and 6, you will get a photo relay. It works as follows. During the day, under high illumination, the phototransistor is open, so the resistance of its collector-emitter section is low, terminals 3 and 6 are closed to each other, and the load is turned off.

With a gradual decrease in illumination in the evening hours, the phototransistor will gradually open, gradually increasing the power in the load, that is, in the lamp. There are no threshold elements in this circuit, so the lamp will light up and go out gradually.

To prevent the photo relay from working at the moment when its own lamp turns on, it is advisable to protect the phototransistor from such illumination. The easiest way to do this is with a plastic tube.

This homemade photo relay is equipped with hysteresis, an extremely necessary function if we use the photo relay as a twilight switch.

Without going into all the details, let's just say that hysteresis in this case is the relay turning on at a low level of illumination, and turning off occurs at a higher level of illumination. That is, providing two different thresholds, one to turn the relay on, the other to turn it off.

Hysteresis serves to prevent, during twilight or cloudy days, continuous switching of the relay at the sensitivity limit of the photocell. In this circuit, it is achieved by including a 4.7 kOhm resistor, which is connected to the emitter of the BC558.

Photo relay operation

At high illumination, the photocell resistance (LDR) is low, hence the voltage across it is almost equal to the supply voltage. For this reason, the BC558 p-n-p transistor is closed, so the second BC548 n-p-n transistor is also closed. The relay will not be active.

At night, the resistance of the photocell (LDR) increases significantly, as a result, the voltage across it will drop, and this will lead to the opening of BC558 (pnp transistors open at a negative voltage at the base in the region of 0.6 volts relative to their emitter). Following this, transistor BC548 opens, and this leads to activation.

Connection diagram for a 220 volt lamp to a photo relay

Diagram for connecting LED lighting sources

For those who want to connect the LED strip, it is necessary to use the auxiliary contacts, which are located next to the relay outputs, as shown in the following figure.

For normal operation of the circuit, you can use a supply voltage from 9 to 15 volts; all that remains is to select a relay for the appropriate voltage.

Printed circuit board of transistor photo relay

This circuit can be adapted as a light barrier. It is enough to simply illuminate our photocell with a beam of light: LED, lamp, laser, etc. That is, there is a photo sensor on one side and a light source on the other.

When a person or animal passes through this "barrier", the light beam is interrupted, causing the relay to operate. To avoid false positives, it is advisable to place the photosensor in a small dark tube.