How to connect the switch LED circuit diagram. Why does an LED lamp flicker connected through a backlit switch. About the features of the operation of circuits for a backlit switch

Today, more and more people are using energy-saving lamps instead of conventional ones. But, despite all the advantages, there are some difficulties in using them.

For example, many customers complain that LED light sources do not work correctly with backlit switches.

For LED lamps, this is a very convenient type of device; its circuit includes a neon indicator, thanks to which you can quickly find the switch in the dark. But, as a rule, such devices are only well combined with and have problems with many modern light sources.

Sample models of illuminated switches and LED lamps are shown in the photo:

Incompatibility is manifested in the fact that the lamp may flash from time to time, emit a weak flicker or glow dimly.

This applies to all LED sources: strips powered by separate units, lamps for reduced power supplies, and direct-on luminaires. Such flickering may depend on the power of the light bulb.. Sometimes these phenomena can be avoided, for example, when the power of the power supply is higher than 100 watts.

The reason for this incompatibility lies in the device. They operate from a constant voltage source, so each device includes a rectifier powered by AC voltage.

An approximate wiring diagram for a backlit switch for LED bulbs is shown in the photo:

To smooth out ripples, the rectifier contains a capacitor. When the light is off, a small current flows through the backlight indicator, but this current is enough to charge the rectifier capacitor. For this reason, the lamp will glow dimly or flicker even when turned off.

Is it worth connecting them together and how to do it right

This flickering creates a lot of problems.. First, it is unacceptable in bedrooms. Secondly, improper operation of the device affects the duration of its operation. This problem can be fixed, there are several ways to eliminate flicker:

When choosing a switch with an indicator, you need to be prepared for the fact that not all modern lighting tools work correctly with them. Nevertheless, the problem in their compatibility is eliminated in several simple ways, therefore, there is no reason to abandon the indicator in the switch or energy-saving lamps.

We bring to your attention a video instruction on how to properly connect an LED lamp with a backlit switch and get rid of the dim glow of the lamp when the switch is off:

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

Illuminated switches are connected in the same way as conventional ones. Any person who wants to stop searching for a switch at night will be able to modify it without even knowing elementary things in electrics. Read the article and you will understand that everything is simple. The switch can be supplemented with an LED according to the simplest schemes. The difference between the schemes is not only in the configuration, but also in the characteristics. For example, an LED switch circuit may not work due to the fact that an LED lamp is installed in the fixtures. Energy-saving lamps can flicker, glow dimly in dark light. Let's look at the pros and cons of each scheme.

Switch backlight circuit on LED and resistance

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

If the switch is "Off", the current flows through R1 (any type, from 100 to 150 kOhm), then through the VD2 LED (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, 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 lighting is used if a luminaire with an incandescent lamp is installed. If there is an energy-saving lamp, you can notice flickering, blinking in the dark. If the luminaire uses LEDs to illuminate the room, then such a circuit will not work due to the fact that the resistance in the luminaire is too high. And it is very difficult to create it in the switch. The scheme is simple, but it has a drawback - the consumption of 1 kWh per month. Here is the diagram.

The ends looking down are connected to the terminals. This scheme is on twists and it is suitable for those who do not have a soldering iron. But it is better to solder the places of twists and insulate them and the resistor.

Switch backlight circuit on LED and capacitor

To increase the efficiency of the glow, a capacitor can be included in the circuit, and the current of the resistor R1 can be reduced to 100 ohms.

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

Of the shortcomings - large dimensions, of the pluses - low energy consumption, 0.05 W * h per month.

Lighting circuit of the switch on a neon light bulb

Such a scheme is devoid of the disadvantages that are present in the above schemes. A big plus is that it is suitable for 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 glows and the resistance R1 (any power, but not less than 0.25 W; 0.5-1 MΩ).

Discharge neon lamps are presented in a wide range, you can choose any. The photo shows a lamp and a resistor having a rating of 200 kOhm. It was removed from the switch of the extension cable of the Pilot computer. It is 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 daylight lamps use a starter, this is a neon lamp built into a cylindrical body. How many starters are in the lamp, so is the number of lamps. To remove it from there, turn the cylinder counterclockwise. Also in the case there is a capacitor that suppresses interference. It is not needed for backlighting.

If the starter was removed from a broken lamp, check the lamp for operation. It is better to take neon from new type starters, as the glass darkens in old ones, which leads to a dim glow.

Attention! Before operating the switch, turn off the power supply. If you have a problem with the dimensions of the resistor, that is, it turned 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 dissipated by one resistor will be equal to the power 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 kΩ resistor.

Let's convert kiloOhms to Ohms, we get 1 kOhm is 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, which is multiplied by their number. For example, to replace a 100 kΩ resistor with three smaller ones, the resistance of each would be 300 kΩ. During installation, the capacitor or resistor should be connected to the phase wire. This is all because the currents that flow through the details of the circuit 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.

During the installation of the switch, it will not work to harm something, because the lamp acts as a current limiter. The worst that can happen is the failure of the elements that you will install. For example, if you take a resistor with a nominal value of 100 ohms instead of 100 kOhm, or do not install it at all.

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

Nyonki can either have a base or be without it. In the second, the conclusions directly come out of the flask. Therefore, the type of installation is different.

Installing a neon bulb with flexible leads in a switch

Usually, the leads that stick out of the light bulb are not long enough to connect them with terminals to the switch, so you need to lengthen 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 place by putting on an insulating tube or wrapping a couple of turns of insulating tape.

To make it convenient to carry out further installation, at the end of the wiring that was soldered, a ring is created using round-nose pliers, for which the switch output will be fixed.

As a rule, manufacturers make white switches. Against its background, the backlight is clearly visible at night and drilling an additional hole for the LED is not required.

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

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

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

Installing a neon light bulb with a base in a switch

The use of a cartridge for illumination is superfluous. Since the life of the light bulb is much longer than the life of the 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 that, solder to the terminals on the lamp.

A wire departs from the central contact of the base, it is necessary to solder a resistor to it at a distance of 2-3 cm from the base. Conclusions are made of the desired length, loops are twisted at their end. 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 shrink tubing.

Or I offer my own way of isolation.

Many are familiar with PVC tubing. It is often used in wire insulation. In order for a piece of tube (cambric) not to fall off, its inner diameter must be smaller than the wire itself. The problem arises that such a cambric is hard to find.

There is no tricky way. If you hold the cambric for about 15 minutes in acetone, it will soften and easily fit on a part that exceeds the inner diameter by 1.5 times. So I isolated the New Year's lamps on a garland.

After the acetone has completely evaporated, the cambric will take on its original form and will be firmly fixed on the wire, the lamp base. It will not be possible to remove it, except to apply acetone again for soaking. This method is similar to a heat shrink tube, with the difference that no heat is required.

A switch with LED or neon lighting is far from uncommon in homes. The use of such switches is quite practical. At night, you do not have to search the wall with your hand to find the switch. With the advent of LED and CFL lamps, big problems began to arise. In particular, most modern LED lamps blink when the switch is off. Today we will figure out how to turn off the backlight on the switch.

This effect occurs due to a closed electrical circuit formed by a resistor with an LED (or neon lamp) and a power converter circuit for LED and CFL lamps. In this article, we will consider the simplest method on the question: how to turn off the backlight in the switch.

How to turn off the backlight on the switch: step 1

How to turn off the backlight on the switch

Disconnect the part where the LED

Disassembled switch with LED inside

Initially, we need to dismantle the switch. Disconnect from the conductors by first disconnecting the switch from the electricity. For those who have already done this more than once, it's a "trivial" occupation.

After the switch is dismantled, it is necessary to remove the casing where the LED itself (or neon) is located.

In our case, the backlight consists of a neon lamp and a 150kΩ resistor. Nothing changes drastically with an LED, so the principle: how to turn off the backlight in a switch with an LED remains the same. The neon lamp is connected through a resistor to the switch terminals.

Illuminated switch wiring diagram

If you quickly throw in the backlight connection diagram in the switch? then it will look like this:

How to turn off the backlight on the switch: step 2

To correct the situation with us, we need to replace the resistor. In our case, we take a 220 kΩ resistor and a 1 N 4007 diode. The diode can be removed from an energy saving lamp, where it is used as a diode bridge. The circuit of the converted switch will look like this:

If we leave the neon lamp, then a 220 kΩ resistor will suffice. If we want to change the indicator to a 3 mm diode, then select a 680 kΩ resistor. This is guaranteed to save you from flashing the diode lamp in the chandelier.

How to turn off video switch light

And finally, watch the video again on how to turn off the LED or neon backlight from the switch so that the lamps do not blink. This is a fundamental solution to the problem. We just bite out all the radio components and don't "worry" anymore. However, this way of dealing with blinking does not satisfy me, so it's better to still use the above example. And the switch does not need to be turned into a simple key and the functions remain.

In contact with

The backlit switch was probably invented by a person who was tired of counting corners while moving around the rooms at night. In fact, such a switch is no different from the usual one, but it has a light bulb that glows in the dark. Most often, LEDs are used for this purpose, which allows not only comfortable use of lighting devices, but also save energy.

The principle of operation of the illuminated switch

There is a wide variety of models of switches with indicators (backlight), but the principle of operation is the same for all. If there is a contact, the light turns on, there is no contact - there is also no main light, but the backlight is on, making it easy to find the switch in the dark.

When the main light is off, the LED on the case lights up, which makes it easy to find the device in the dark

Inside the switch, if you remove the keys, you can see the LED. It is the main element of the backlight, which only works when the light is off. In addition to the LED, the circuit has a current-limiting resistor. It is thanks to him that the energy coming from the input phase is enough to power the backlight, but not enough to turn on the lights in the house.

If the switch contact is open, current flows through the backlight circuit and turns on the LED

Voltage is applied to the incoming phase of the switch L. From it, current flows either to the backlight circuit if the switch contact is open, or directly to the lamp if the contact closes. In the second case, the current does not pass to the resistor and the LED, because the resistance of this section of the circuit is greater than that of a direct wire to the lighting fixture.

Types of switches depending on the type of backlight

With current limiting resistor. The disadvantage of this scheme is that it does not work if LED lamps are installed in home fixtures and chandeliers. This is due to the fact that when using them it is impossible to create a high current for backlighting (the resistance of LED lamps is much greater than that of incandescent lamps). Energy-saving lamps with this scheme can glow in the dark.
Capacitor LED. A backlight with a capacitor is used to increase efficiency and reduce power consumption during backlight operation. The resistor here serves to limit the charge current of the capacitor.
With neon light. Neon-lit switches have virtually no drawbacks. Here, any lamps can be used throughout the house: fluorescent, LED, incandescent.

Connecting a light switch

Regardless of the shape and number of light control keys, the installation and connection of the switch is carried out according to the same principle. It can be most easily explained using the example of a single-key device.

Installation of a single switch

Before starting installation work, it is necessary to de-energize the room.

Then the old switch is dismantled, if it was previously installed. For this:

As a result, we will have the inside of the old switch in our hands, which can be disposed of or left for spare parts.

To properly mount a new switch, you must follow the same scheme as when removing it, only in reverse order, that is:

It should be noted that the process of connecting a backlit switch is no different from connecting a conventional device.

Video: how to connect a single-gang backlit switch

Installation and connection of switches with several keys

In everyday life, switches with several keys are often used. With their help, you can control the operation of several lines of lighting devices at once. They are installed in large rooms or, if necessary, turn on and off the light in several rooms from one place.

The installation of such switches is completely similar to that described above, with the only difference being that one phase wire and several (according to the number of keys) wires from consumers will come from the wall. It is important to connect them in the correct order.

Video: how to connect a three-gang switch with a socket

Connecting a backlit switch

A switch is called a pass-through switch, which consists of two parts. The first is installed at the beginning of any path, for example, in front of the stairs to the second floor. The second part is mounted at the end, i.e. at the entrance to the floor. Thus, the lighting of the stairs can be turned on at the bottom, and turned off after the ascent.

To install a pass-through switch, you will need to lay a cable of three cores to both switches. The connection diagram of the switches is usually given on their packaging. The installation of each device is completely similar to that described above.

To connect the pass switch to each of the devices, you need to stretch three wires and connect them according to the scheme that is included in the kit.

Video: how to connect a pass switch

Turn off the backlight of the switch

The backlight of the switch can be turned off. This is done quite simply, you just need to turn off the power and remove the LED.

Sequencing:

How to install the backlight in the switch yourself

You can make an indicator in the switch yourself. The sequence of operations is as follows:

This circuit is mounted if incandescent lamps are used in the fixtures. In the off position, current flows through the resistor and the LED, causing it to glow. The current in this case is about 3 mA, which is quite enough to power the LED bulb.

There is also a circuit for connecting the backlight on a neon lamp. Its advantage is that any light bulbs can be used in lamps and chandeliers: LED, fluorescent, incandescent.

If you install a neon light instead of an LED, the switch will work with all types of lamps

As we said above, there is also a scheme for manufacturing a switch with a backlight on the capacitor. With a capacitor, the backlight system is more stable and consumes less power than a resistor. But you can not use it with LED lamps either.

Capacitor circuit can be used with halogen and incandescent lamps

Video: backlight in the switch

If the backlight flickers

It happens that the backlight starts to blink. What to do in this case? It is necessary to check the voltage in the network and the supply of current. If everything is fine, then the diode has become unusable, a replacement is needed. To make a switch indicator, follow steps 1-9 from the section on turning off the backlight, cut the strands in the place where the wires go to the light bulb. Remembering the connection points of the diode with the outgoing phase and the resistor, take a new indicator and connect it to the contacts. Wrap the twisting points with electrical tape or put a plastic tube on them. Next, reassemble the switch and test the backlight.

Illuminated switches are not a tribute to fashion, but convenience, because everything is being improved for the benefit of humanity.

Even having lived in an apartment all my life, turning on the light in absolute darkness does not always work right away. Switches with LEDs will help you not to probe the entire surface of the walls every time, it will make it possible to quickly and easily orient yourself on the spot by the backlight.

There are factory devices with built-in indicators based on LEDs or lamps. But such a switch is not always suitable for specific operating conditions - 2- and 3-button devices are quite difficult to find.

A simple circuit will help you assemble and connect your switch with an LED. Additional advantages of such a backlight are the ability to monitor the health of the wiring, lamps and the switch itself. To implement the plan, you will need a few simple radio components and a little time.

What may be required?

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

The main role in the installation of the switch backlight is assigned to the LED (VD1). It must be connected to the switch terminals through a limiting resistor (R1). The backlight circuit should also include a protection LED (VD1) that will get rid of reverse voltage troubles.

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

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

incandescent lamps will work normally;
energy-saving ones may start to flicker;
LED-based lighting may not work with this circuit due to the high self-resistance of the elements.

It is possible to eliminate some of the shortcomings of the circuit, increase efficiency and reduce energy consumption (from 1 kW / h to 0.05 kW / h 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 watts.

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

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

Stages of connecting the backlight

Connecting the LED does not require any special skills, it is only important not to neglect the safety rules, to 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 in the decorative panel of the switch, drill a hole with a diameter of about 2 mm.
Insert the LED, if necessary, fix it with glue.
Assemble the switch.
Restore power supply.
Check the functionality of the circuit.

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

Switches with LEDs can act as an impromptu night light, so it is important to be careful about choosing the brightness and hue of the device. Most often, it is red LEDs that are mounted, although the choice can be stopped at green, blue and even ordinary white ones. More complex circuits will help to implement a separate indication for each key of 2-button and 3-button switches, but such backlighting is not very popular and is characterized by complex implementation.

Some people need instructions so that when the device burns out, they find out what they did wrong.

Making a switch backlight with an LED with your own hands is not difficult. An extremely simple circuit is assembled literally “on the knee” within a few minutes. But, if you don't want everything to end with fireworks and burnt wiring, read this article carefully.

Scheme for turning on the LED in the switch in the apartment

Scheme and appearance of the switch

As you can see, the device consists of only two elements - a current-limiting resistor and a light source.

For many people who are not related to radio electronics, this scheme can be confusing. After all, we put the LED in a 220V AC switch, although the LED itself is designed for a voltage of 2-12V DC. And the main lamp, in theory, should also glow with such a connection.

How and why does it work?

Recall the school physics course:

Voltage - potential difference at the two ends of the conductor. The higher the voltage, the faster the electrons run through the wires.
Current strength - electron density in a conductor. When an area with high resistance is encountered in an electrical circuit on the path of electrons, some of them give up their energy to this area.

When the current strength (electron flux density) is significantly greater than this section is able to pass, the excess energy is converted into heat. If there were no resistor in front of the diode, the current passing through it would exceed its nominal parameters many times over, turning the diode crystal into a cloud. In this circuit, the resistor acts as a gate, cutting off most of the current. A current will also flow through the incandescent lamp itself, but its strength is so small that the spiral will not heat up.

Calculation of circuit parameters

We select a resistor for the LED. In this formula, the mains voltage is taken as 320V, since it is necessary to take into account not the nominal parameter, but the effective peak voltage.

We select a resistor

How to make a backlight for a switch

The main purpose of the LED illuminated switch circuit is to limit the amount of current flowing through the LED. For a diode, it doesn’t matter at what speed electrons pass through it, it will take its “portion” and convert it into a glow. If the density of the electron flux is higher than its throughput, the excess will be released in the form of heat, melting the crystal.

Installation LED in the 220V switch, diagram:

Options for connecting an LED

Option 1

This connection method will work, but for a very short time, a few milliseconds, until the incandescent lamp coil flares up. With this connection, the circuit current will be calculated based on the needs of the lamp, exceeding the needs of the LED by hundreds of times. This is the wrong option.

Option 2

This is already a viable option. The current limiting resistor R1 will reduce the current to the required value. For a normal 20 mA LED, the resistor value should be:

(320V-3V) / 0.02A≈16 kOhm and power 0.25-0.5W.

For the sake of increasing the life of the backlight and reducing the heating of the resistor, it is better to increase the resistance parameters by 3-4 times. Such a scheme can be seen if you disassemble a cheap Chinese switch with an LED. There is no reverse current protection, which does not contribute to the long life of such a device.

Option 3

Turning on the diode with reverse polarity protects the LED from the reverse half wave. This is important if there are powerful devices on the line in the network: washing machine, boiler, electric kettle. You can use any small diode with voltage up to 500-1000 volts.

Calculation examples

Since our task is only to illuminate the switch and achieve maximum viability, we take the LED current 30% of the nominal value - 6mA

Resistor current limiter

Usd = 3.5V, Isd = 20mA (0.02A) - We make the calculation for 6mA (0.006A);

R1 \u003d (330-3.5) / 0.006 \u003d 55000 Ohm (55 kOhm). In order to reduce heating, the resistor value can be increased by 2 times to 100 kOhm.

Resistor power P=Ur1 I=327 0.006=2W.

In parallel with the LED, it is better to turn on the 1000V diode in a mirror.

Capacitive current limiter

Instead of a resistor, you can use a high-voltage capacitor, R1 is necessary for self-discharge of the capacitor C1. The capacitive circuit does not heat up.

C1=Rc/(2 π £)=50kOhm/(2 3,14 50Hz)=150uF; C1=150uF*500V;

R1 \u003d 0.5-1 MΩ;

Diode as in the previous design.

If the switch is intended for an energy-saving lamp, it is better to replace the LED with a neon light bulb, the donor of which will be the starter of the fluorescent lamp. Classical circuits, due to the damping of a half-wave, can cause flickering of "energy savers". The connection principle remains the same, but due to the higher rated current, about 100mA, the resistor or capacitive resistance (on a neon light bulb) should be increased to 500-600 kOhm.

Application area

switch circuit with LED backlight;
power indicator in a portable extension cord;
miniature night light;
outlet lighting.

If desired, you can connect led strip, but only on a capacitive limiter after careful recalculation.

This is what the LED light looks like

How to connect on a live example

Below is a diagram of how to connect a switch with an LED. Connection instructions

Before starting the installation of the LED circuit in the switch, make sure that the switch is disconnected from the "phase". This can be done with a simple screwdriver tester.

Check the insulation quality of all connecting contacts. Jumping bare wires, at best, will disable the backlight circuit, at worst, the wiring in the apartment.

If necessary, a mounting hole can be made in the plastic part for the LED so that it evenly illuminates the switch button.

We collect the resulting design and enjoy the result.

If we use the resistor option, it is worth experimenting with the resistance parameters. The diode can “start” from 2V or 3V, respectively, in the second, the resistor value can be reduced.

Do not forget that in such devices only the density of electrons is limited, the voltage remains the same and is still dangerous for living organisms.

Some people need instructions so that when the device burns out, they find out what they did wrong.

Scheme for turning on the LED in the switch in the apartment

Scheme and appearance of the switch

As you can see, the device consists of only two elements - a current-limiting resistor and a light source.

How and why does it work?

Recall the school physics course:

Voltage - potential difference at the two ends of the conductor. The higher the voltage, the faster the electrons run through the wires.
Current strength - electron density in a conductor. When an area with high resistance is encountered in an electrical circuit in the path of electrons, some of them give up their energy to this area.

Calculation of circuit parameters

We select a resistor for the LED. In this formula, the mains voltage is taken as 320V, since it is necessary to take into account not the nominal parameter, but the effective peak voltage.

We select a resistor

How to make a backlight for a switch

Installation LED in the 220V switch, diagram:

Options for connecting an LED

Option 1

Option 2

This is already a viable option. The current limiting resistor R1 will reduce the current to the required value. For a normal 20 mA LED, the resistor value should be:

(320V-3V) / 0.02A≈16 kOhm and power 0.25-0.5W.

Option 3

Turning on the diode with reverse polarity protects the LED from the reverse half wave. This is important if there are powerful devices on the line in the network: a washing machine, a boiler, an electric kettle. You can use any small diode with voltage up to 500-1000 volts.

Calculation examples

Since our task is only to illuminate the switch and achieve maximum viability, we take the LED current 30% of the nominal value - 6mA

Resistor current limiter

Usd = 3.5V, Isd = 20mA (0.02A) - We make the calculation for 6mA (0.006A);

R1 \u003d (330-3.5) / 0.006 \u003d 55000 Ohm (55 kOhm). In order to reduce heating, the resistor value can be increased by 2 times to 100 kOhm.

Resistor power P=Ur1 I=327 0.006=2W.

In parallel with the LED, it is better to turn on the 1000V diode in a mirror.

Capacitive current limiter

Instead of a resistor, you can use a high-voltage capacitor, R1 is necessary for self-discharge of the capacitor C1. The capacitive circuit does not heat up.

C1=Rc/(2 π £)=50kOhm/(2 3,14 50Hz)=150uF; C1=150uF*500V;

R1 \u003d 0.5-1 MΩ;

Diode as in the previous design.

Application area

switch circuit with LED backlight;
power indicator in a portable extension cord;
miniature night light;
outlet lighting.

If desired, you can connect an LED strip, but only on a capacitive limiter after careful recalculation.

This is what the LED light looks like

How to connect on a live example

Below is a diagram of how to connect a switch with an LED. Connection instructions

Before starting the installation of the LED circuit in the switch, make sure that the switch is disconnected from the "phase". This can be done with a simple screwdriver tester.

Check the insulation quality of all connecting contacts. Jumping bare wires, at best, will disable the backlight circuit, at worst, the wiring in the apartment.

If necessary, a mounting hole can be made in the plastic part for the LED so that it evenly illuminates the switch button.

We collect the resulting design and enjoy the result.

If we use the resistor option, it is worth experimenting with the resistance parameters. The diode can “start” from 2V or 3V, respectively, in the second, the resistor value can be reduced.

Do not forget that in such devices only the density of electrons is limited, the voltage remains the same and is still dangerous for living organisms.

What may be required?

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

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

incandescent lamps will work normally;
energy-saving ones may start to flicker;
LED-based lighting may not work with this circuit due to the high self-resistance of the elements.

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

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

Stages of connecting the backlight

Connecting the LED does not require any special skills, it is only important not to neglect the safety rules, to 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 in the decorative panel of the switch, drill a hole with a diameter of about 2 mm.
Insert the LED, if necessary, fix it with glue.
Assemble the switch.
Restore power supply.
Check the functionality of the circuit.

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

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

On a neon lamp

Switch circuit with backlight on a neon lamp:

As you can see, in this connection, when the key breaks the main lighting circuit, the 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 normally shine, but the lamp itself will not turn on. This moment 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, the current will begin to flow through the main circuit, because, as we remember from school books on physics, electric current always passes through the circuit with less resistance (the resistor in this case is an obstacle to turning on illumination).

Such a connection scheme for a single-gang backlit switch is the simplest and even a novice in electrics can use it. In two-key models, everything is the same, just instead of one lamp, 2 will be installed, for 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 tutorial that clearly shows the process:

Installation and wiring instructions

LED

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

The resistance of the 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 - the resistance in the chandelier will be too high and as a result - the lamp will constantly flash. To know,