Wiring diagram for a switch with a veko diode. Illuminated switch for LED lamps. Step-by-step instructions for installing in a backlight switch

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 at night can make small changes to this device, even if they do not have special electrical knowledge.

You can insert an LED into any switch using fairly 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, are of high quality, from which they have 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 regular switch opens or closes a circuit carrying electric current, while a pass-through switch, connecting one line, 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 backlit switch, the connection diagram of which is identical to those discussed, 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 illuminated 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 lights 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 a different number of keys, any results in the implementation of design ideas and projects can be easily achieved. And the ease of installation makes it possible to carry out the work independently, without resorting to the services of expensive specialists.

On store shelves you can see illuminated switches. But not everyone wants to replace a conventional installed switch. And I don’t want to look for it in the dark either.

Backlit switches are connected in the same way as regular ones. Any person who wants to stop searching for a switch at night can modify it even without knowing basic electrical knowledge. Read the article and you will understand that everything is simple. The switch can be supplemented with an LED using the simplest circuits. The difference between the schemes is not only in the configuration, but also in the characteristics. For example, a switch circuit based on an LED may not work due to the fact that an LED lamp is installed in the lamps. Energy-saving lamps may flicker and glow dimly in dark environments. Let's look at the disadvantages and advantages of each scheme.

Switch illumination circuit using LED and resistance

As a rule, to illuminate the switch, it is enough to install an LED according to the diagram below.

If the switch is “Off”, current flows through R1 (any type, from 100 to 150 kOhm), then through the LED VD2 (lit). VD2 is protected from voltage breakdown by diode VD1. For a good glow, R1 is suitable, the current of which is 3 mA. If the LED light is too weak, you need to reduce the resistance. VD1, VD2 – any type and color of glow. To independently calculate the parameters of the resistor used, you should remember the law of current strength. LED backlighting is used if a lamp with an incandescent lamp is installed. If there is an energy-saving lamp, you may notice flickering and blinking in the dark. If the lamp uses LEDs to illuminate the room, then such a circuit will not work because the resistance in the lamp is too high. And it is very difficult to create it in a switch. The scheme is simple, but it has a drawback - consumption of 1 kWh per month. Here's the diagram.

The ends facing downwards are connected to the terminals. This circuit is twisted and is suitable for those who do not have a soldering iron. But it’s better to solder the twists and insulate them and the resistor.

Switch illumination circuit using an LED and a capacitor

To increase the efficiency of the glow, you can include a capacitor in the circuit and reduce the current of resistor R1 to 100 Ohms.

The difference between this circuit and the previous one is that the capacitor serves as a replacement for resistor R1. R1 (100 - 500 Ohm; 0.25 W) in turn acts as a charge current limiter.

The disadvantages are large dimensions, the advantages are low energy consumption, 0.05 Wh per month.

Switch illumination circuit on a neon light bulb

This scheme is devoid of the disadvantages that are present in the above-described schemes. The big advantage is that it is suitable for lamps using both energy-saving and LED lamps, as well as incandescent lamps.

When the switch is open, the current flows through the gas-discharge lamp HG1, which lights up, and resistance R1 (any power, but not less than 0.25 W; 0.5-1 MΩ).

Gas-discharge neon lamps are presented in a wide range, you can choose any one. The photo shows a lamp and a resistor rated at 200 kOhm. It was removed from the extension switch of the Pilot computer. It can be built into any switch without additional modification. Such lamps can be found in electric kettles, a device with an indication.

These lamps are everywhere. Are you surprised? All fluorescent lamps use a starter, this is a neon lamp built into a cylindrical housing. The number of starters in a luminaire equals the number of lamps. To remove it from there, turn the cylinder counterclockwise. There is also a capacitor in the case that suppresses interference. It is not needed when making illumination.

If the starter was removed from a broken lamp, check the functionality of the lamp. It is better to take neon glass from new type starters, since in old ones the glass darkens, which leads to a dull glow.

Attention! Before working on the switch, turn off the electrical power. If you have a problem with the dimensions of the resistor, that is, it turns out to be large and does not fit, replace it with several small ones connected in parallel.

When resistors are connected in parallel, the power that is dissipated by one resistor will be equal to the power that is divided by the number of resistors. Their value will become smaller and will be equal to the value divided by the quantity. For example, we need a 1 W, 100 kOhm resistor.

Let's convert kiloOhms to Ohms, we get 1 kOhm equal to 1000 Ohms. Therefore, this resistor can be replaced by two, connected in series in the circuit, each with a power of 0.5 W and a nominal value of 50 kOhm.

If the connection is parallel, the calculation is carried out in the same way. The difference is that the nominal voltage of the resistor is equal to the value that is multiplied by their number. For example, to replace a 100 kOhm resistor with three smaller ones, the resistance of each must be 300 kOhm. During installation, the capacitor or resistor should be connected to the phase wire. This is all because the currents that flow through the circuit parts are not higher than a couple of milliamps. Therefore, there are no special requirements for the quality of existing contacts. If the box in which the circuit will be mounted is made of metal, you need to take care of the insulation of the wires.

When installing the switch, it will not be possible to harm anything, because the lamp acts as a current limiter. The worst thing that can happen is that the elements you will be installing fail. For example, if you take a resistor with a nominal value of 100 Ohms instead of 100 kOhms, or do not install it at all.

Step-by-step instructions for installing in a backlight switch

Nionki can either have a base or be without it. For the second, the leads come directly out of the flask. Therefore, the type of installation is different.

Installing a neon light bulb with flexible leads into a switch

Usually, the leads that stick out from the light bulb are not long enough to connect them with terminals to the switch, so you need to extend them with a piece of copper wiring. The wire used can have either one core or many. It is best to solder these wires to the terminals of the light bulb.

Before you start soldering, you need to strip the wires and tin these places with solder. Then connect the wires with an allowance of at least 5 mm and solder.

After soldering, do not forget to insulate the area by putting on an insulating tube or wrapping a couple of turns of insulating tape.

To make further installation convenient, a ring is created at the end of the wiring that has been soldered using pliers, to which the switch terminal will be secured.

As a rule, manufacturers make white switches. Against its background, the backlight is clearly visible even at night and there is no need to drill an additional hole for the LED.

Then, solder the resistor to the second terminal of the lamp. And then a piece of wire to it in the same way as the first one. We need it to connect the second output of the switch.

We perform a similar operation with the second output. We isolate the soldering area with a tube or insulating tape, twist the ring and attach it to the second terminal of the switch.

The backlight is mounted and connected to the electrical wiring. The work is almost complete, you just need to make a key to turn on the backlight.

Installing a neon light bulb with a socket into a switch

Using a socket for illumination is unnecessary. Since the life of a light bulb is much longer than the life of a switch. Therefore, instead of using a cartridge, we simply solder the base to the wires.

To do this, remove the insulation from the wires, tin them with a soldering iron and make small loops. After this, solder to the terminals on the lamp.

A wire extends from the central contact of the base; a resistor must be soldered to it at a distance of 2-3 cm from the base. The leads are made to the required length, and loops are twisted at their ends. We carry out the same operation with the second terminal of the resistor.

The threaded part of the base, as well as the resistor, must be insulated. This is done using insulation or heat-shrinkable tubing.

Or I offer my own method of isolation.

Many people are familiar with PVC tubes. EE is often used for wire insulation. In order to prevent a piece of tube (cambric) from coming off, its internal diameter must be smaller than the wire itself. The problem arises that such a cambric is difficult to find.

There is no tricky way. If you hold the cambric for about 15 minutes in acetone, it will soften and easily fit onto a part that is 1.5 times larger than the internal diameter. This is how I insulated the New Year's lamps onto the garland.

After the acetone has completely evaporated, the cambric will take its original form and will be tightly attached to the wire and lamp base. It will not be possible to remove it, unless you use acetone again to soak it. This method is similar to heat shrink tubing, with the difference that no heat is required.

After all the work has been done, the backlight is installed in the switch box and connected to the contacts.

Illuminated switches for electrical appliances

Illuminated switches can be seen on carriers, heating devices, and electrical appliances. Often, such lighting consists of a neon lamp and a resistor. Once I had the opportunity to carry out repair work on the Pilot extension cord. It had a cracked key that fell out and prevented it from being turned on.

After the switch was disassembled, I was surprised. There was no current-limiting resistor in it. Neon lamps are not connected to a 220 V current without a resistor, which serves as a current limiter. Such a device will fail in the first moments of operation. In the photo you can see the key from the neon lamp mounting side and the front one.

The resistance that I measured between the lamp terminal and the spring was 150 kOhm. This switch has an interesting design. Resistors, and there are two of them, are installed in the holes in the keys, pressed by a spring to the lamp terminals, which ensures good contact. These springs press the movable contacts located in the switch. When the switch is turned on, voltage is supplied to the neon lamp.

Using a backlight circuit for display

The backlight also serves so that you can track whether the switch is operational or not. If the backlight is on, but the light does not turn on, the switch is faulty. If the backlight does not work, the indication lamp has burned out.

The circuit option is suitable for indicating any devices and electrical circuits. Let's say that when you connect a lamp to a fuse, you can find out when it will burn out. If the electrical appliance does not have an indication, it can be built in. This way, it will be easy to monitor whether the device is working.

LED or neon indication helps to quickly determine where the light switch is located at night. If you have a regular switch installed in your room and you want to convert it to a backlit model, below we will provide some simple examples. We immediately draw your attention to an important point - for a lamp with, you can use an electrical circuit with LEDs, but if the chandelier is LED, you need to use a simpler option - with a neon bulb. So, here are simple diagrams for connecting a backlit switch to your attention.

On a neon lamp

Illuminated switch diagram on a neon lamp:

As you can see, in this connection option, when the key breaks the main lighting circuit, current flows through the resistor to the neon bulb, which lights up. The resistor is needed in order to lower the voltage to such a value at which the indication will glow normally, but the lamp itself will not turn on. This point is very important, because... even with the lights off, as you can see, the neon bulb completes the circuit. When the key is switched to the “on” position, current will begin to flow through the main circuit, because, as we still remember from school physics books, electric current always passes through the circuit with less resistance (the resistor in this case is an obstacle to turning on backlight).

This circuit for connecting a single-key backlit switch is the simplest and even a novice in electrics can use it. In two-key models, everything is similar, just instead of one lamp there will be 2 installed on each key, as shown in the diagram below:

If you want to make an LED indication, a more complex connection option is provided below. We also recommend watching a video lesson that clearly shows the process:

Instructions for installation and connection of wires

On LEDs

The diagram for connecting an LED to a single switch is as follows:

The resistance of resistor R1 must be at least 100 kOhm. The LED must be protected from voltage breakdown using a diode. As we said above, this connection option will not work if LED lamps are installed in the chandelier. The reason is that the resistance in the chandelier will be too high and as a result, the lamp will constantly blink. To know,

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 backlit 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 value of 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 that dissipates almost 2 W of power will be large and heat up so much that it can deform it upon contact with the plastic case. 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 with a rectifier diode (usually 1N4007) connected in series with the LED (Fig. 2). In this case, not an alternating voltage of 220V is applied to the circuit elements, but a constant voltage - 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 lighting 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 install a limiting resistor of 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 lamp reaches 80 thousand hours. That is why backlit switches that use a 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 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 a short circuit, hide most of the leads together with the resistor under a heat-shrinkable tube, leaving the edges bare for connection to the terminals.
If necessary, extend the assembled structure 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 such a simple design as a switch illumination is not without its drawbacks. First of all, this applies to LED lamps, inside of which an electronic unit – a driver – is installed. 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 from an LED lamp;
The backlight may not work at all with some models of LED lamps - their driver breaks the electrical circuit.

Similar problems arise when a backlit switch interrupts the circuit of a fixture containing a compact fluorescent lamp, due to the presence of a switching power supply in it. 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 save you from reverse voltage troubles.

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.