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How to make a backlit switch for LEDs. Advantages of an illuminated switch. Operating principle of an illuminated switch

In houses, apartments and other premises where electricity is supplied, switches must be installed. Modern models allow you not only to turn the lighting on/off, but also to program the operation of individual devices and systems, for example, heated floors.

Among all the varieties, the most convenient to use are those equipped with backlighting. Installing and connecting an illuminated switch has its own nuances and rules.

How does a backlit switch work?

The main difference between a backlit device and classic models is the presence of an indicator. This could be a neon light or LED.

The connection diagram is simple. The indicator runs parallel to the device terminals. When the devices are turned off, this small part is connected to the zero wire (using the lamp resistance) and begins to glow. When the light is turned on, the circuit is short-circuited and the indicator turns off.

A backlit/indicator switch will not work with the following types of devices:

fluorescent lamps;
lighting devices with electronic starting controllers;
some types of LED lamps.

By functionality, devices are distinguished as one-, two-, three- and four-key, corded and push-button, etc.

Illuminated switches have many advantages:

The design and construction are almost the same as standard devices. The only difference is the presence of an LED on the front panel, which makes being in dark room more comfortable.
Most schemes are economical. Built-in indicators consume very little power.
Maintenance of the LED does not require large energy consumption.

Often backlit devices are installed in bedrooms. Working backlight helps you quickly find your way around the room if you suddenly wake up.

Important! Disadvantages include consumption large quantity electricity when connected using separate circuits (using a resistor).

Types depending on the type of backlight

The parameter for dividing into types, in addition to functionality, will also be the type of backlight:

With resistor. This circuit for connecting a backlit switch has a drawback - it will not work if the lighting fixtures have LED lamps. It's easy to explain. When such devices operate, it will not be possible to create high voltage, because LEDs have higher resistance than incandescent lamps. You can connect here energy saving light bulb, but it blinks after turning off.
LED with capacitor. The circuit allows you to increase efficiency and reduce the level of electrical energy consumed by the backlight. The resistor here acts as a current limiter for the capacitor.
With neon lamp. Switches of this type have almost no disadvantages. Able to work with any lighting devices, including conventional lamps, fluorescent and LED.

All of the above types of devices are used in everyday life.

Connection rules

Regardless of the type, installing an illuminated switch is the same. The differences are only in a couple of nuances.

Installation of a single switch

The easiest way is to connect a single-key (single) backlit switch. First of all, you need to turn off the power and remove the old switch.

For this:

Use a flathead screwdriver to remove the key.
Carefully remove the decorative trim.
Unscrew the screws connecting the device to the socket box. Pull it out.
Loosen the fastenings and disconnect the wires.

At the end of the manipulations, the inside of the dismantled switch remains on your hands. They are thrown away or used as spare parts.

To install a new light switch with indicator/backlight, you must repeat the steps listed above, only in reverse order:

Insert the “internals” into the socket box, not forgetting to attach the wires to the switch contacts.
Screw in the bolts.
Install a decorative frame.
Insert a key.
Turn on the electricity to check the correct installation and connection. If the work is done correctly, the diode in the backlight will light up.

Installation and connection of switches with several keys

Connecting a double or triple backlit switch is done in much the same way. To install a design with two keys, you will need a screwdriver, side cutters, tips and an indicator with which to determine the phase.

The work is carried out like this:

As in previous case, first of all, it is necessary to turn off the power to the apartment/house. Next, the dismantling of the old device begins.
Remove the keys and unscrew the screws. There will be three wires left in the socket box. One is incoming power, two more are power going to the lighting fixture.
Now, using an indicator screwdriver, you need to find the phase wire, mark it or simply remember it. You need to act extremely carefully, because this stage requires the presence of voltage in the network.
Disconnect the network.
Strip the wires of insulation.
Get a new device. It has three contact groups and a pair of wires coming from the backlight.
Using a measuring device, determine the “Off” position. Typically, the wiring coming from the LED has special contact plates for screws. The screw must be unscrewed, placed against the plate and screwed back. Repeat the action for the remaining contacts.
Attach the phase wire to a plate located separately from the rest with a screw.
Connect the wire going to the chandelier to the contact and secure it.
Secure the last wire under the contact on which there are no plates.
Check that the connection is correct.
Insert the inner part of the switch into the installation box.
Secure the screws.
Reinstall the keys.

Upon completion of installation, connect the electricity and check the functionality of the device.

If necessary, control the light source with different places a walk-through/changeover switch should be installed. Its main difference from classical models is the presence of a moving contact. If you press the on/off key, it will transfer from one contact to another, starting the operation of the second circuit.

Connecting a pass-through switch with backlight

The connection diagram for the pass-through switch is extremely simple. Two separate devices are installed on both sides of the circuit.

To do this, you will need to lay a three-core cable to one and to the other. When the first switch is turned on, the circuit will close and the lamp will light. When the second one is turned on, the light will turn off.

Turning off the switch backlight

The device allows you to temporarily or permanently turn off the firefly. It's easy to do:

As in other cases, you must first turn off the power.
Using a flathead screwdriver, pry out and then remove the keys.
Remove the decorative frame.
Unscrew the bolts.
Remove the internal filling from the socket/installation box.
Using an indicator screwdriver, check for voltage on the wires.
Disconnect the wires from the contacts.
Find the latch in the switch design that holds the two parts together. Separate them.
Find the resistor and LED.
Take wire cutters and cut the wires directed towards the backlight. An alternative option is to desolder the LED.
Reassemble the switch by repeating the above steps in reverse order.

Now the indicator will not work.

How to install the backlight in the switch yourself

The circuit and design of the backlit switch are simple. It is possible to assemble the device at home with your own hands. It is enough to purchase a regular switch and an LED.

The scheme consists of main parts:

Light-emitting diode;
limiting resistor;
diode connected in parallel with the LED.

For LEDs, a resistor with a nominal value of 100 kOhm and a power of at least 1 W is suitable. For protection, a KD521 diode should be used.

Note! This scheme has the disadvantage of high power consumption. Its quantity can reach 1 kW per month.

To save energy, you can use another circuit that limits the LED current using a capacitor. Its capacitance should be 1 µF. When connecting the circuit, a resistor will be connected after the capacitor, limiting the charge current. This scheme has a drawback that concerns the installation process. Often capacitors are of considerable size, which can lead to difficulties with their installation in the switch.

Designs that use LEDs as backlighting work harmoniously exclusively with conventional incandescent lamps. The fluorescent lamps in such a circuit will blink after being turned off. LED lighting fixtures will not work at all, since the resistance of the lamp is always higher.

A more effective circuit with a neon lamp includes a series connection of a resistor with a resistance of 0.5 to 1 mOhm.

Installing the backlight into the switch is very simple. The LED or neon lamp must be fixed to the body using regular glue. You need to drill a hole in the key for the light.

Conclusion

Wiring switches with LED, neon, etc. is quite easy to do. The process resembles the installation of a conventional device and does not depend on the type (one-, two- or three-key).

The circuits are so simple that you can install the lighting yourself, using a minimum of time and effort. You just need to purchase a regular switch and indicator.

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Switches with an indicator (backlit) are convenient devices that allow you to quickly find the switch in a dark room. Illumination is carried out using a neon lamp installed in the switch housing.

With their appearance, the functionality of the switches has increased, but the problems have not decreased. After all, each mechanism has its own characteristics.

How does the switch work?

The phase coming to this switch is connected to the L - incoming contact (Fig. 2), and from the outgoing contacts it goes to the lighting lamps. The moving contacts are closed to each other.

A backlight circuit is installed, which includes a resistor and a “neon” - a neon bulb, and is soldered to contacts L1 and L. Thus, when contacts L and L1 are open, the neon bulb is lit, and when the light is turned on, these contacts are closed by a moving contact, which eliminates backlight circuit diagrams.

What should you pay attention to?

When choosing a switch with an indicator, it is necessary to operate with the power consumption of all lighting devices connected to the switch. The markings and rated current (maximum permissible) current are indicated on the inside of the switch. Basically, switches are produced for a current of 10 and 16 A and, accordingly, maximum power connections for them are 2.2 and 3.5 kW.

It should also be noted that you should not use backlit switches to work with energy-saving (fluorescent) lamps. Because it flickers when turned off Powersave lamp, and this “behavior” of the lamp is unlikely to please anyone.

Currently, there are special types of lighting devices - a flickering candle lamp, which imitate the fluttering of a flame in the wind.

Why does the lamp flash when installing an illuminated switch?

Many users have problems with energy-saving lamps when installing a switch with an indicator, and the question arises as to why the energy-saving lamp is blinking. The fact is that when the switch is in the off state, the current passing through the signal circuit of the neon or LED light bulb charges the electronic ballast capacitor, which is located inside the lamp. This is a common reason why energy-saving lamps flicker - the voltage reaches the trigger value and the lamp flashes, after which the capacitor is discharged and the process is repeated again as it charges.

If the switched-off lamp blinks, you can remove the backlight from the switch or place a resistor or another capacitor in parallel with the lamp.

Currently, some manufacturers of lighting devices have taken into account the problem when the lamp blinks after turning off, and solved it by shunting the lamps or increasing the turn-on delay time - soft start.

Many users have problems with energy-saving lamps when installing a switch with an indicator, and the question arises as to why the energy-saving lamp is blinking.

This solution to the problem when it flashes LED lamp, is optimal. Technologically, 1-2 seconds are allotted for increasing the power of these lamps, however, the disadvantages of these lamps include reaching full brightness only after 1-1.5 minutes.

Another reason why lamps flicker may be an incorrect connection, when zero and not phase goes through the switch. Thus, if the LED lamps flicker, you can reconnect the switch yourself or call a specialist for this. In addition, if a fluorescent lamp flickers, this may not depend on the quality of the lamp itself. In this case, you need to try turning off the indicator.

Thus, when purchasing a switch with an indicator, it is best to choose lamps with smooth start, and during installation, carefully check that the wires are connected correctly, in this case, problems when the energy-saving lamp flashes after turning off will not be terrible.

If searching for a switch every day in a dark room takes a lot of time and nerves, and moving it to a more convenient place is not possible, then the problem can be solved with the help of backlighting, which will accurately indicate the location of the light switch keys. In practice, this is realized by adding an LED to an existing switch with your own hands or by replacing it with a similar illuminated switch with a built-in neon bulb.

Scheme and principle of operation of backlight using LED

The connection diagram for a switch with LED backlight is shown in Fig. 1. The principle of its operation is based on Ohm's law and is quite simple. At the moment when the contacts of switch Q1 are open, the load current flows through the circuit L – R1 – LED – HL – N. The load current does not exceed the operating current through the LED, that is, 10 mA. Naturally, this current is not enough to light the main lighting lamp. For comparison, a 60 W incandescent lamp consumes 270 mA. In addition, the main part of the 220V network voltage drops not at the lamp, but at the resistor. As a result, only the LED lights up, and its brightness depends on the resistance of resistor R1. As soon as the light is turned on in the room, the resistance of the switch contacts located parallel to the LED with the resistor will become close to zero. The current flow circuit will close through L – Q1 – HL – N. The load current will follow the path with the least resistance and the LED will go out.

By the way, if you unscrew the lamp from the lamp or it burns out, the backlight will stop working.

Calculating the backlight on an LED comes down to choosing the right resistor R1. The fact is that 99% of the mains voltage drops across it, which means the power dissipation is quite high. For example, given an LED current of 8 mA, let’s calculate the resistor parameters: A resistor dissipating almost 2 W of power will have big sizes and heat up so much that upon contact with the plastic case it can deform it. Because of this drawback, the considered option has not found practical application.

In order to reduce heat losses and protect the LED from breakdown, the switch illumination circuit is supplemented rectifier diode(usually 1N4007) connected in series with an LED (Fig. 2). In this case, no AC voltage 220V, and constant - 0.45 times less, that is, approximately 100V. The resistor value can be set in the range of 12-50 kOhm and experimentally select an option in which the brightness of the illuminating LED and the temperature of the resistor surface will be optimal. The advantages of DIY LED backlighting include the ability to independently choose the color of the LED, its size and installation location.

Illumination using a neon lamp

The circuit and principle of operation of a backlit switch with a neon lamp is completely identical to that with an LED, but has improved performance. The main advantage of a neon light bulb is its extremely low current consumption, which does not exceed 1 mA, and ideally should be 0.1-0.2 mA. This allows you to set the limiting resistor much lower power and size, namely: It turns out that a miniature resistor with a power of 0.125 W easily fits under the case and does not heat up at all. Compared to an LED circuit, this option is more economical, reliable and safe. And the service life of a neon light bulb reaches 80 thousand hours. That is why backlit switches that use neon lamp, have found wider practical application.

Connecting a single-key switch with backlight

To assemble and then connect the backlit switch to a 220V network, you will need a little time and following the steps below in the instructions.

It is necessary to de-energize the room in which the modernization and installation of a backlit switch will be carried out.
Remove the light on/off switch by carefully prying it off from the sides with a screwdriver.
Remove the switch from the wall and disconnect the wires.
Depending on the shape and size of the housing, determine the installation location of the LED.
Drill a hole with a diameter of 5 mm in the marked location.
Solder a resistor to one of the LED terminals, and a diode to the second, observing the polarity.
To avoid short circuit, most hide the leads together with the resistor under a heat-shrinkable tube, leaving the edges bare for connection to the terminals.
If necessary assembled structure extend with wires.
Use superglue to secure the LED in the hole.
Clamp one of the backlight wires together with the “phase” into the switch terminal.
Connect the other backlight wire, together with the wire going to the lamp, to the second terminal of the switch.
Install the finished switch with LED in the reverse order.

If you plan to use a finished product, then steps 4 to 9 are skipped.

Connecting a two-key switch with backlight

In 90% of cases, the design of a two-key backlit switch is no different from its single-key counterpart. The only exceptions may be exclusive models from foreign manufacturers. Basically, inside the switches with two lighting control keys there is one neon light bulb with a resistor, as shown in the photo.
It’s easy to guess that the backlight will light up and go out only when you press one of the keys. However, switch manufacturers do not see the need to install a second neon light, since one indicator light is sufficient for illumination in the dark.

The sequence of actions for assembling the backlight of a two-key switch is the same as for single-key models. We only note that the electrician, at the moment of connecting the wires, has the right to choose which key the neon light will go off when pressing. If we are talking about assembling the LED backlight with your own hands, then if you wish, you can install 2 LEDs - on each of the keys separately.

Possible future problems

Even this simple design Like the backlight of the switch, it is not without its drawbacks. First of all, this applies to LED lamps, inside of which there is a the electronic unit– driver. Due to the presence of the backlight, there is a small potential on the base of the turned off LED lamp, which affects the operation of the driver. Since the circuitry of the drivers is designed differently, problems in the operation of the lamp can manifest themselves in different ways, namely:

in the form of an unpleasant flicker;
in the form of a dim glow of an LED lamp;
The backlight may not work at all with some models of LED lamps - their driver breaks the electrical circuit.

Similar problems occur when an illuminated switch breaks the circuit of a light fixture with a compact fluorescent lamp, due to the presence in it pulse block nutrition. Therefore, before buying a backlit switch or upgrading an existing one, you should be sure that an incandescent or halogen lamp will be connected to it. Otherwise, you should be prepared to eliminate negative flicker and dim glow.

What might you need?

There are several ways to connect an LED to a switch. First, you should decide whether the indicator will be inside the housing or outside.

The main role when installing the switch backlight is given to the LED (VD1). It must be connected to the switch terminals through a limiting resistor (R1). The backlight circuit should also include a protective LED (VD1), which will eliminate the trouble of reverse voltage.

The resistor value is selected taking into account the color and brightness of the LED, and the possibility of heating the elements should also be taken into account. Devices of different shades may differ significantly in their basic characteristics. On average, the operating range of the resistor is 100-150 kOhm at a power of over 1 W. If the LED does not shine brightly enough, the resistance value can be reduced slightly.

When developing a lighting scheme, it is worth considering the type of lamp:

incandescent lamps will operate as usual;
energy-saving ones may begin to flicker;
LED-based lighting may not work with this circuit due to the high intrinsic resistance of the elements.

You can eliminate some of the shortcomings of the circuit, increase efficiency and reduce energy consumption (from 1 kW/hour to 0.05 kW/hour per month) by installing an additional capacitor, which will act as a current-limiting element. In this case, the resistor value will also need to be lowered to approximately 100-500 Ohms at a power of about 0.25 W.

The main disadvantage of connecting a capacitor is the increase in the dimensions of the indicator.

Using a similar scheme, illumination of sockets and other interior elements based on LEDs can be connected.

Stages of connecting the backlight

Connecting an LED does not require any special skills; it is only important not to neglect safety rules and perform all actions carefully so as not to damage the existing wiring.

Turn off the power supply.
Assemble the selected circuit, connect the elements to the switch terminals.
To output the LED, a hole with a diameter of about 2 mm should be drilled in the decorative panel of the switch.
Insert the LED and secure it with glue if necessary.
Assemble the switch.
Restore power supply.
Check the functionality of the circuit.

The backlight will only work when the light is off, when the light is on, the LED will not be visible.

Switches with LEDs can serve as an impromptu night light, so it is important to carefully choose the brightness and shade of the device. Most often it is red LEDs that are installed, although the choice can be made of green, blue and even ordinary white. More complex circuits will help to implement a separate indication for each key of 2- and 3-button switches, but such backlighting is not particularly popular and has a complex implementation.

In stores you can often find switches that already have a built-in backlight. However, it is unlikely that anyone will want to simply change the installed switch. But searching for a key in the dark by touch is also not always convenient.

Practicality of illuminated switches

An illuminated switch, the wiring diagram of which is almost the same as that of conventional switches, has become very popular. Anyone who is tired of searching for a light switch in the dark of night can make small changes to this device, even if they don't have special knowledge in electrics.

You can insert an LED into any switch using quite simple circuits. The available schemes differ from each other in their characteristics, and not just in their configuration. For example, a switch may not want to work due to the fact that an LED lamp is installed in the lamp. If the lamps are energy-saving, they may glow in the dark or flicker, which is also not the correct result.

Switch connection diagrams

There are many acceptable schemes, each of which has its own pros and cons. Understanding existing backlight switches is not difficult.

For example, an illuminated switch, the connection diagram of which is presented below.

When the switch is in the "Off" position, the current passes through the resistance (R1 - any, in the range from 100 to 150 kOhm). After resistance, it passes through VD2 (the LED that lights up). In order to protect the LED from voltage, we install a diode VD1. A resistor with a current of 3 mA shines especially well with this connection scheme. If it turns out that the LED glows rather weakly, then the resistance value should be reduced. Any LED or diode in this circuit will do. You can also calculate the required resistor parameters yourself. It is enough just to remember the classical law of current strength.

Let's consider another backlit switch, the connection diagram of which is extremely simple, but with a slight drawback. The fact is that it consumes about 1 kilowatt per month.

We connect the downward ends to the terminals. If you don’t have a soldering iron at home, or for some reason you don’t want to tinker with it, then this circuit is ideal. It is made on twists. Although, for reasons of safety and durability of the device, it is still better to solder the connections and properly insulate the resistor.

LED backlight circuit for a switch with a capacitor

To increase the glow level by an order of magnitude, you can use a capacitor. On the contrary, reduce the resistor current to 90-100 Ohms. You can use a backlit switch, the connection diagram of which differs from the previous one in that a capacitor is used instead of a resistor. And the resistor (R1) acts as a charging current limiter.

True, the backlight assembled according to this scheme is large in size, but it has extremely low power consumption - about 0.05 watts per month.

Connecting a pass-through switch

If we consider the Legrand backlit switch, the connection diagram of which is above, then it should be noted that it is distinguished by the safety of using this product, which is made of materials that significantly increase its service life. And there is no need to talk about the ease of connecting switches from this company, everything is so well thought out and easy to implement.

In the manufacture of switches, polycarbonate and galvanized steel are used. The screws, grips and support are all made of this metal. The keys, mechanisms, body and frame are made of polycarbonate. And this is a guarantee that for a long time with backlighting, the connection diagram of which is extremely simple, it will not crack or be destroyed by solar radiation.

Installation of a two-key switch

Two-key Legrand is distinguished by the presence of a pair of contacts, independent of each other. When you press the keys, they switch the upper lines to the lower ones, and at the same time the upper contacts are made with the absence of a final output. And the lower contacts are connected to the second, same pass-through switch.

Knowing how the left and right groups of contacts are arranged, it is easy to understand how to connect a pass-through switch.

Connecting a pair of pass-through switches is extremely simple. The phase that leaves the electrical panel of the apartment or house is supplied to the contact of the second switch, while within the entire group the contacts are connected to each other by a jumper. And those contacts that are in the left group supply current to lighting devices independent of each other. It is important to consider one rule here. Under no circumstances should these two contacts be connected to each other. Then all four cross contacts need to be linked together as a pair.

Legrand switches

"LeGrand" is perhaps the most widespread brand among electrical appliances, and therefore most people prefer to use their products, or those close to them, but also from well-known companies.

Among the products related to electrical fittings, it is necessary to highlight sockets suitable for television and telephone networks - low-current, and all of them, in addition to excellent design, have high quality, from where they gained wide popularity not only in our country, but throughout the world.

Operating principle of pass-through switches

Externally, an ordinary switch is practically no different from a pass-through switch, and it is impossible to visually distinguish them without revealing the design. The difference lies in the internal structure. A conventional switch opens or closes a circuit that carries electricity, and the pass-through, connecting one line, at the same time disconnects the other. That is, in other words, when the pass-through switch is operating, no matter which pair of keys is pressed, the switch is ready for operation. We pressed the left one on one switch and the light went out. We pressed the second one on it, or the key on the second switch - the light comes on again. This is undoubtedly very convenient.

In other words, for a regular single-key switch both contacts are working, but for a pass-through switch there are as many as three. Because the second contact, which acts as an output contact, is connected to the second switch, a pair. And when connecting two-key pass-through switches, the number of contacts increases to six.

If you carefully examine the connection diagram below, you can easily cope with the installation of any pass-through switches and install all the necessary devices so that the circuit functions normally. The main thing is to follow safety precautions, not to work when the mains voltage is on, and to make sure that a workable circuit is used.

with backlight

Let's consider, perhaps, the most undemanding circuit with which you can connect such switches. Zero in the diagram is indicated in blue. Once it enters the junction box, it is then directed to the lighting lamp. The orange wire is a phase. It passes from the same box to the input of the first of the switches. Then the black wires on the outputs need to be connected to the input terminals of the second switch. And then, with just one wire, go to the lamp.

A double illuminated switch, the connection diagram of which is identical to those considered, is used as a device for controlling lighting sources that are spaced apart from each other and can be located at a considerable distance. But they need to be managed from a specific place, and sometimes from two or three.

The effect of comfort is especially noticeable when using a two-key backlit switch, the connection diagram of which is included in the kit, on stairs, in large rooms, when you don’t want to get up, for example, from the bed to turn off the light in the bedroom. If the switch is located by the door, this is inconvenient before bed. Therefore, it is more logical to use a pass-through switch. One is installed as usual, near the door in the room, and the second near the bed, so that you can turn off the light without getting up.

Automatic adjustment of turning off and turning on the light is often used. To do this, use detectors that respond to movement or sound. Or for lighting - when it gets dark, the light bulb will turn on on its own and vice versa.

Thus, if a single-key backlit switch is used, the connection diagram of which has already been discussed, as well as pass-through switches with varying amounts keys, any results in the implementation of design ideas and projects are easily achieved. And the ease of installation makes it possible to carry out the work independently, without resorting to the services of expensive specialists.