Smooth dimming of LEDs. Manufacturing of boards and assembly of devices for smooth ignition of LEDs

The ever-expanding scope of applications for excellent performance LEDs is revealing to consumers their additional capabilities. One of the properties that highlight the advantages of LED luminaires is the smooth switching of the LED, which significantly expands their design capabilities.

Prospects for the use of smooth ignition of LEDs

Unusual arrangements of LED lamps are increasingly used in the automotive industry, in the design of buildings and premises, and in creating an indescribable atmosphere of play of light at various public events. Considering the ability to independently install a soft-start LED, we can expect even greater distribution in the coming years. Even a simple circuit for smoothly igniting and turning off LEDs significantly increases the comfort of their use:

• the backlight on the devices turns on/off smoothly, without blinding the driver at night;
• the interior light comes on gradually when the doors are opened;
• Smooth switching on of side lighting significantly extends the life of LED lamps.

It is noteworthy that the device for smooth ignition of LED lamps, with low power consumption, requires only parallel installation of a polar capacitor. The capacitance of the capacitor should not be more than 2200 μF, and its positive terminal is soldered to the anode wire of the LED. Negative terminal - connects to the cathode wire.

Advantages of thyristor-based LEDs

There is an anecdote going around the Internet that in response to the question whether the light on the modem was blinking, the user replied that the light was blinking, but it was not a light bulb, but a thyristor LED, which confused the provider’s technical support workers, since such LEDs are simply can not be.

A thyristor can only act as a kind of key that controls a powerful load, as well as a switch. The definition of thyristor LED appeared after lamp manufacturers replaced the expensive diode bridge used to drive LEDs. By creating a device consisting of 2 thyristors connected in parallel and in opposite directions, we managed to get rid of the diode bridge. Thanks to the fact that such a unique thyristor LED was used, the price of LED lamps decreased significantly and became acceptable to the buyer.

The properties of an electronic key make it possible to create not only a smooth switching on of LEDs - thyristors are also used in circuits that provide gradual switching on/off of even simple incandescent lamps (special switches). Considering the reasonable price of LED lamps without a diode bridge, the smooth switching on and off of LEDs on a thyristor significantly expands the scope of application of this modern and effective means of illumination and illumination.

Smooth ignition and extinction can be done by yourself

The so-called polite lighting in a car is referred to as the smooth ignition and decay of LEDs or their boards. This is necessary to prevent accidental blinding. The smoothness of switching on makes the light source visually impressive. The article contains several variants of schemes that will help to arrange smooth illumination not only in the car interior, but also inside the headlights.

On the Internet there is an abundance of schemes for smooth switching on and fading of LEDs (with a voltage of 12V or more), which you can do yourself. They all have certain advantages and disadvantages, different levels of complexity, and differences in the quality of the electronic circuit.

Often, there is no point in constructing bulky boards with expensive parts and other contents. It is worth noting that smoothly turning on an LED on one transistor, as well as turning it off, is technically possible. Only a single transistor with a small connection will be sufficient for the correct and gradual activation of the LED crystal. The following is a diagram that is easy to implement and does not require expensive materials. Switching on and off is carried out using a positive drive.

When voltage is applied, current flows through resistor R2 and optimizes capacitor C1. It is worth considering that the voltage in the capacitor cannot change instantly, and this plays into the hands of the smooth opening of transistor VT1. The gate current that continues to rise (pin 1) passes through resistor R1, and also builds up a positive potential at the drain itself (output 2) of the transistor. As a result, the LEDs light up smoothly. When the power is deactivated, a break occurs in the functioning electrical circuit along the positive (control) side. In turn, the capacitor gradually discharges and transfers its energy to R1 and R3 (resistors). The discharge and its speed are determined by the value of resistor R3. As the resistance increases, the accumulated energy will go to the transistor. This means that the attenuation process will take longer. In order to be able to adjust the time of full switching on and deactivation of the voltage, the circuit can be diversified with resistors R4, as well as R5. Despite this, for correct operation, it is better to use this circuit with resistors R3 and R2 with a small operating value.

It is worth considering that each of the circuits can be folded independently, even on a small board. It is necessary to consider the elements of the circuit in more detail. The main control component is the n-channel transistor IRF540. A transistor is a semiconductor-type device that is capable of generating or amplifying oscillations. The drain voltage of the transistor can reach 23 A, as well as 100 V – drain-source voltage. Instead of the transistor indicated in the circuit, you can use KP540 (domestic analogue). Resistance R2 is responsible for igniting the LEDs and smoothly turning them off, the value of which should not exceed 30–68 kOhm. It is worth noting that a resistor is a component of passive type electrical circuits, which is characterized by a variable or certain indicator of electrical resistance. The main function of a resistor is to linearly convert voltage to current and vice versa, etc.

Resistance R3 with an operating range of 20–51 kOhm is responsible for smooth decay (switching off). To set the gate voltage, there is a resistance R1, the nominal value of which is 10 kOhm. The capacitance of capacitor C1 (minimum) must reach 220 µF with a maximum voltage of about 16 V. If the capacitance is increased to 470 µF, then the time to completely turn off and ignite the LED will increase. If you purchase a capacitor that operates at high voltage, you will need to increase the board itself.

Control and its adjustment by “minus”

To control the given circuit by minus, it is necessary to refine it. For example, you should replace the transistor with a “p-channel” one; the IRF9540N is suitable for this. Next, the negative terminal of the capacitor must be connected to the point of three resistors, which is common to them. The positive terminal should be connected to the source of VT1. The circuit to be modified will have reverse polarity in its power supply, and the positive contact will be replaced by a negative one during control.

Arduino: secrets of working with it

Arduino is a tool for creating various electronic devices, designed for non-professional users. We are talking about the design of robotics and automation systems. Devices running on Arduino can receive signals from various sensors and control actuators.

Arduino is a small board equipped with individual memory and processor that interacts with its environment. This feature significantly distinguishes such a device from a PC, which does not leave the virtual world. In addition, Arduino is capable of working together with a computer or in standalone (individual) mode.

There are several dozen contacts on the device board. It is to them that you can connect: sensors, LEDs, expansion cards, motors, etc. It is worth loading an application for Arduino or a sketch into the processor itself; it is capable of receiving all readings, as well as controlling devices, according to a given algorithm. It is worth noting that the outputs on the Arduino board are called Pin, so after downloading the sketch it will become clear how to work with such a tool.

Is it possible to smoothly turn on an LED on an Arduino? To begin with, it’s worth using a simplified sketch for smooth ignition of LEDs. The brightness of the LEDs will be changed using PWM. To do this you will need the following components:

1. Arduino Uno board;
2. Light-emitting diode;
3. Breadboard board;
4. 220 Ohm resistor;
5. Wires.

It is worth knowing that AnalogWrite (function) is used to attenuate and slowly ignite the LED. It is AnalogWrite that uses pulse width modulation (PWM). It allows you to activate and deactivate a digital pin at high speed, developing a slow decay process.

To connect an LED to Arduino, you need to connect its longer leg (anode) to digital pin No. 9, which is located on the board, using a 220 Ohm resistor. Then, the shorter leg of the LED (cathode with a negative charge) should be directed towards the ground.

led-svetodiody.ru

Scheme for smooth switching on of incandescent lamps (UPVL) 220v, 12v

Any economical owner of a house or apartment strives to use electrical energy rationally, since its prices are quite high. For example, if a conventional incandescent lamp is used incorrectly, it will regularly “burn out.” Therefore, in order for it to serve you much longer, experts recommend using devices such as soft-start devices. You can also make such a block yourself using a certain scheme.

Operating principle of UPVL

With a sharp flow of electricity, the incandescent lamp wears out very quickly and the tungsten filament burns out. But if the temperature conditions of the filament and the electric current are approximately the same, then the process will be stabilized and the lamp will not burn out. In order for light sources to work as expected, you must have a special power supply.

Thanks to a special sensor, the filament will heat up to the required temperature, and the voltage level will increase to a point specified by the user. For example, up to 176 Volts. In this case, the power supply will help to significantly increase the life of the lamp.

Device for smooth switching of lamps

The protection unit has one drawback - the light in the room will burn much weaker.

If the voltage is 176 V, the lighting level will decrease by about two-thirds. Therefore, experts recommend purchasing powerful lamps so that the quality of light is normal. Currently, there are special soft-start units (UPVL) for incandescent lamps, which differ in different power parameters. Therefore, before buying a unit, you need to make sure whether it can withstand large surges or voltage drops in the electrical network. Such a device must have an additional reserve, and it will be enough if the voltage in your electrical network is about 30 percent greater than the surge flow.

You need to know that the higher the standard value, the larger the dimensions of the power supply. Currently, you can purchase a power supply with a power of 150 to 1000 watts.

Types of power supplies and their characteristics

Today there are many different devices for smooth activation of LN. The most popular are:

Scheme

In order to correctly use LC soft-start units, it is necessary to use special electrical circuits. Thanks to such diagrams, you can easily understand how this device works and is designed from the inside, as well as how it should be used.

Scheme of smooth switching on of an incandescent lamp

Usually, when connecting such a device, specialists use the simplest and easiest version of the circuit. Sometimes a special scheme is used with the introduction of simisters. Also, in addition to blocks of this type, you can take field-effect transistors, which operate similarly to soft-start devices.

The second scheme for smooth switching on of incandescent lamps

Also, in order to control the voltage in the soft start device, you can use automatic devices.

What is a thyristor circuit?

Thyristor circuit for smooth lamp switching on

The rectification bridge circuit (Fig. VD1, VD2, VD3, VD4) uses a light bulb (Fig. EL1) as a load and current limiter. The rectifier arms are equipped with a thyristor (Fig. VS1) and a bias circuit (Fig. R1, R2 and C1). Also, the diode bridge is installed due to the specification of the operation of the thyristor device.

After voltage is applied to the circuit, the electric current begins to flow through the filament coil and enters the bridge, and then the electrolyte is charged through a resistor. When the opening voltage limit of the thyristor is reached, it begins to open and then the current from the light bulb passes through it. As a result, the tungsten filament heats up gradually and smoothly. The period of its heating will depend on the capacity of the capacitor and resistor located in the circuit of the device.

What is remarkable about the triac

This circuit has fewer parts due to the use of a triac (Fig. VS1), which serves as a power switch.

Triac circuit for smooth switching on of lamps

An element such as a choke (Fig. L1), which is designed to remove various interference that appears during the opening of the power switch, can be removed from the general circuit. (Fig. R1) The resistor is a current limiter that flows to the main electrode (Fig. VS1). The circuit that sets the time is made of a resistor (Fig. R2) and a capacitance (Fig. C1), powered by a diode (Fig. VD1). This scheme works the same as the previous one. When the capacitor is charged to the level of the opening voltage of the triac, it begins to open, and then electric current flows through it and the light bulb.

Smooth switching diagram for incandescent lamps

In the photo below we can see a triac regulator. Such a device, in addition to adjusting the power in the load, also smoothly supplies electric current to the light bulb when it is turned on.

Device for smooth switching on of incandescent lamps

Scheme of operation of a block on a specialized microcircuit

The Kr1182pm1 type microcircuit was specially created by specialists to build various phase regulators.

Smooth start circuit on a specialized chip

In this case, what happens is that the microcircuit itself regulates the voltage on the source, which has a power of up to 150 watts. And if you need to control a stronger load system and dozens of lighting fixtures simultaneously, then an additional power triac is simply connected to the control circuit. In the picture below we can see how this happens.

Smooth start circuit with power triac

The use of soft-start units does not end only with conventional lamps, as experts recommend using them together with halogen lamps with a power of 220 V.

It is important to know! Such units cannot be installed with fluorescent and LED lamps. This is due to the fact that there are different techniques for developing circuits, as well as the principle of operation and the presence of each lighting device with its own source of measured heating for fluorescent lamps or whether there is no need for such regulation of LED lamps.

Soft start device (UPVL) for incandescent lamps 220V and 12V

Today, a large number of different UPVL models are produced, which differ in function, cost and quality. The device, which is sold in specialized stores, is connected in series to a 220 V light source. We can see the circuit and appearance of the device in the photo below.

Scheme of a soft switching device for 220 V lamps

If the power supply for the lamps is 12 or 24 V, then the device must be connected in front of the step-down transformer, also in series with the initial primary winding.

The device must correspond to the load that will be connected with a certain margin. To do this, you need to calculate the number of lamps and their total power.

Since the device is small in size, the UPVL can be placed under a chandelier, in a socket box or in a connection box.

Dimmers or dimmers

It is economically profitable and rational to use devices that create a smooth switching on of lamps, as well as provide the process of regulating their degree of brightness. Dimmers of various models can:

• Set operating programs for lighting fixtures;
• Smoothly turn lamps on and off;
• Controlled by remote control, voice commands or clapping.

When purchasing this device, you must immediately make a choice in order to know what functions are required and not buy an expensive device for a lot of money.

Before installing a dimmer, you need to decide on the method and location of lighting control. To do this, you will need to install the appropriate type of electrical wiring.

Connection diagrams can be of varying degrees of complexity. In any case, you must first turn off the voltage from a certain area.

In the figure we showed the simplest connection diagram. Here, instead of a simple switch, you can make a dimmer.

Connection diagram for dimmer to lamp power supply

The device is connected to the break of the L-wire with the phase, and not the N-neutral one. Between the zero and the dimmer there is a lighting fixture. The connection to it comes out serial.

Figure (B) shows a circuit with a switch. The connection process remains the same, but here a simple switch is added. It is usually installed near the door at a certain gap between the phase and the dimmer itself. Near the bed there is a dimmer that allows you to control the lighting while lying down. When a person leaves the room, the light turns off, and when he comes back, the lamp starts up with the same brightness level.

In order to control a chandelier or other lighting fixture, you can take two dimmers, which will be located in different corners of the room (Fig. A). The two devices are connected to each other via a junction box.

Incandescent lamp control circuit: a - with two dimmers, b - with two pass-through switches and a dimmer

Thanks to this connection system, you can adjust the brightness level from different places independently of each other, but more wires will need to be installed.

Pass-through switches are used to turn on lamps from different places in the room (Fig. B). Also, you must turn on the dimmer, otherwise the lamps will not respond to the switches.

Dimmer characteristics:

• The dimmer saves electricity by only 15%, and the rest is used by the regulator.
• The devices are highly sensitive to temperature increases. Therefore, they cannot be used at temperatures above 27°C.
• The load level should not be less than 40 W, since the life of the regulator is significantly reduced.
• Dimmers should be used only for those types of devices that are recommended by the manufacturer and written in the data sheet.

Video: UPVL device

UPVLs can significantly increase the service life of halogen and incandescent lamps. These are small and inexpensive devices that can be bought at any store and installed yourself, having a specific diagram and strictly following the manufacturers' instructions.

tehznatok.com

Do-it-yourself diagram for smoothly switching on an incandescent lamp

During the ongoing burnout of incandescent lamps, including on the landing, several incandescent lamp protection schemes were implemented on the Internet. Their use has yielded positive results - lamps have to be changed much less frequently. However, not all implemented device circuits worked “as is” - during operation it was necessary to select the optimal set of elements. At the same time, a search was made for other interesting schemes. As you know, smooth switching on of incandescent lamps increases their service life and eliminates current surges and interference in the network. In a device that implements this mode, it is convenient to use powerful field-effect switching transistors. Among them, you can choose high-voltage ones, with an operating voltage at the drain of at least 300 V and a channel resistance of no more than 1 Ohm.

Scheme for smooth switching on of incandescent lamp No. 1

The author gives two schemes for soft starting of lamps. However, here I want to offer only a circuit with an optimal operating mode of the field-effect transistor, which allows it to be used without a radiator at a lamp power of up to 250 Watts. But you can study the first one - which is simpler in that it is included in the break of one of the wires. Here, after charging the capacitor, the voltage at the drain will be approximately 4...4.5 V, and the rest of the network voltage will drop across the lamp. In this case, the transistor will release power proportional to the current consumed by the incandescent lamp. Therefore, at a current of more than 0.5 A (lamp power 100 W or more), the transistor will have to be installed on a radiator. To significantly reduce the power dissipated by the transistor, the machine must be assembled according to the diagram given below.

Scheme for smooth switching on of incandescent lamp No. 2

The diagram of a device that is connected in series with an incandescent lamp is shown in the figure. The field-effect transistor is included in the diagonal of the diode bridge, so it receives a pulsating voltage. At the initial moment, the transistor is closed and all the voltage drops across it, so the lamp does not light. Through diode VD1 and resistor R1, capacitor C1 begins to charge. The voltage across the capacitor will not exceed 9.1 V, because it is limited by the zener diode VD2. When the voltage across it reaches 9.1 V, the transistor will begin to open smoothly, the current will increase, and the voltage at the drain will decrease. This will cause the lamp to light up smoothly.

But it should be taken into account that the lamp will not start to light immediately, but some time after the switch contacts are closed, until the voltage on the capacitor reaches the specified value. Resistor R2 serves to discharge capacitor C1 after the lamp is turned off. The drain voltage will be insignificant and at a current of 1 A will not exceed 0.85 V.
When assembling the device, 1N4007 diodes from used energy-saving lamps were used. The zener diode can be any low-power one with a stabilization voltage of 7...12 V.

I found a BZX55-C11 at hand. Capacitors - K50-35 or similar imported ones, resistors - MLT, S2-33. Setting up the device comes down to selecting a capacitor to obtain the required lamp ignition mode. I used a 100 uF capacitor - the result was a pause of 2 seconds from the moment the lamp was turned on until the moment the lamp ignited.

It is also important that the lamp does not flicker, as was observed in the implementation of other schemes.

This device has been working for a long time and the incandescent lamps have not yet had to be changed.

usamodelkina.ru

Smooth turning on and off of LEDs

This article will consider several options for implementing the idea of ​​smoothly turning on and off the LEDs for the instrument panel illumination, interior light, and in some cases, more powerful consumers - dimensions, low beam and the like. If your instrument panel is illuminated using LEDs, when the lights are turned on, the backlighting of the instruments and buttons on the panel will light up smoothly, which looks quite impressive. The same can be said about the interior lighting, which will gradually light up and fade out smoothly after closing the car doors. In general, this is a good option for tuning the backlight :).

Control circuit for smooth switching on and off of the load, controlled by plus.

This circuit can be used to smoothly turn on the LED backlight of a car dashboard.

This circuit can also be used for smooth ignition of standard incandescent lamps with low-power coils. In this case, the transistor must be placed on a radiator with a dissipation area of ​​about 50 square meters. cm.

The circuit works as follows. The control signal is supplied through 1N4148 diodes when voltage is applied to the “plus” when the side lights and ignition are turned on. When any of them is turned on, current is supplied through a 4.7 kOhm resistor to the base of the KT503 transistor. At the same time, the transistor opens, and through it and the 120 kOhm resistor the capacitor begins to charge. The voltage on the capacitor gradually increases, and then through the 10 kOhm resistor it enters the input of the field-effect transistor IRF9540. The transistor gradually opens, gradually increasing the voltage at the output of the circuit. When the control voltage is removed the KT503 transistor closes. The capacitor is discharged to the input of the field-effect transistor IRF9540 through a 51 kOhm resistor. After the capacitor discharge process is completed, the circuit stops consuming current and goes into standby mode. The current consumption in this mode is negligible. If necessary, you can change the ignition and decay time of the controlled element (LEDs or lamps) by selecting the resistance values ​​and capacitance of the 220 μF capacitor.

With proper assembly and serviceable parts, this circuit does not require additional settings.

Here is a version of a printed circuit board for placing the parts of this circuit:

Scheme of smooth switching on and off of LEDs.

This circuit allows you to smoothly turn on and off the LEDs, as well as reduce the brightness of the backlight when the dimensions are turned on. The latter function can be useful in the case of excessively bright backlighting, when in the dark the instrument lighting begins to dazzle and distract the driver.

The circuit uses a KT827 transistor. Variable resistance R2 is used to set the brightness of the backlight when the lights are on. By selecting the capacitance of the capacitor, you can adjust the time the LEDs light up and go out.

In order to implement the function of dimming the backlight when the lights are turned on, you need to install a double headlight switch or use a relay that would be activated when the lights are turned on and close the switch contacts.

Smooth turning off of LEDs.

The simplest circuit for smooth fading of the VD1 LED. Well suited for implementing the function of smooth fading of interior light after closing the doors.

Almost any diode VD2 will do; the current through it is small. The polarity of the diode is determined in accordance with the figure.

Capacitor C1 is electrolytic, large capacity, the capacity is selected individually. The larger the capacitance, the longer the LED lights up after the power is turned off, but you should not install a capacitor with too large a capacitance, since the contacts of the limit switches will burn due to the large charging current of the capacitor. In addition, the larger the capacitance, the more massive the capacitor itself, and problems with its placement may arise. Recommended capacitance is 2200 µF. With such a capacity, the backlight fades out within 3-6 seconds. The capacitor must be designed for a voltage of at least 25V. IMPORTANT! When installing the capacitor, observe the polarity! If the connection polarity is incorrect, the electrolytic capacitor may explode!

This article will consider several options for implementing the idea of ​​smoothly turning on and off the LEDs for the instrument panel illumination, interior light, and in some cases, more powerful consumers - dimensions, low beam and the like. If your instrument panel is illuminated using LEDs, when the lights are turned on, the backlighting of the instruments and buttons on the panel will light up smoothly, which looks quite impressive. The same can be said about the interior lighting, which will gradually light up and fade out smoothly after closing the car doors. In general, this is a good option for tuning the backlight :).

Control circuit for smooth switching on and off of the load, controlled by plus.

This circuit can be used to smoothly turn on the LED backlight of a car dashboard.

This circuit can also be used for smooth ignition of standard incandescent lamps with low-power coils. In this case, the transistor must be placed on a radiator with a dissipation area of ​​about 50 square meters. cm.

The scheme works as follows.
The control signal is supplied through 1N4148 diodes when voltage is applied to “plus” when the side lights and ignition are turned on.
When any of them is turned on, current is supplied through a 4.7 kOhm resistor to the base of the KT503 transistor. At the same time, the transistor opens, and through it and the 120 kOhm resistor the capacitor begins to charge.
The voltage on the capacitor gradually increases, and then through a 10 kOhm resistor it is supplied to the input of the field-effect transistor IRF9540.
The transistor gradually opens, gradually increasing the voltage at the output of the circuit.
When the control voltage is removed, the KT503 transistor closes.
The capacitor is discharged to the input of the field-effect transistor IRF9540 through a 51 kOhm resistor.
After the capacitor discharge process is completed, the circuit stops consuming current and goes into standby mode. The current consumption in this mode is negligible. If necessary, you can change the ignition and decay time of the controlled element (LEDs or lamps) by selecting the resistance values ​​and capacitance of the 220 μF capacitor.

With proper assembly and serviceable parts, this circuit does not require additional settings.

Here is a version of a printed circuit board for placing the parts of this circuit:

This circuit allows you to smoothly turn on and off the LEDs, as well as reduce the brightness of the backlight when the dimensions are turned on. The latter function can be useful in the case of excessively bright backlighting, when in the dark the instrument lighting begins to dazzle and distract the driver.

The circuit uses a KT827 transistor. Variable resistance R2 is used to set the brightness of the backlight when the dimensions are on.
By selecting the capacitance of the capacitor, you can regulate the time of ignition and extinction of the LEDs.

In order to implement the function of dimming the backlight when the lights are turned on, you need to install a double headlight switch or use a relay that would be activated when the lights are turned on and close the switch contacts.

Smooth turning off of LEDs.

The simplest circuit for smooth fading of the VD1 LED. Well suited for implementing the function of smooth fading of interior light after closing the doors.

Almost any diode VD2 will do; the current through it is small. The polarity of the diode is determined in accordance with the figure.

Capacitor C1 is electrolytic, large capacity, the capacity is selected individually. The larger the capacitance, the longer the LED lights up after the power is turned off, but you should not install a capacitor with too large a capacitance, since the contacts of the limit switches will burn due to the large charging current of the capacitor. In addition, the larger the capacitance, the more massive the capacitor itself, and problems with its placement may arise. Recommended capacitance is 2200 µF. With such a capacity, the backlight fades out within 3-6 seconds. The capacitor must be designed for a voltage of at least 25V. IMPORTANT! When installing the capacitor, observe the polarity! If the connection polarity is incorrect, the electrolytic capacitor may explode!

Recently I decided to put together a circuit that would allow me to smoothly light up any LED strip (whether in a car or at home). I didn’t reinvent the wheel, and decided to Google a little. When searching on almost every site, I found circuits where the LED load is severely limited by the capabilities of the circuit.

I wanted the circuit to just gradually increase the output voltage, for the diodes to light up smoothly, and for the circuit to be passive (it did not require additional power and would not consume current in standby mode) and would definitely be protected by a voltage stabilizer to increase the lifespan of my backlight .

And since I haven’t learned how to etch boards yet, I decided that first I need to master the simplest circuits and during installation use ready-made circuit boards, which, like the rest of the circuit components, can be purchased at any radio parts store.

In order to assemble a circuit for smooth ignition of LEDs with stabilization, I needed to purchase the following components:

In general, a ready-made circuit board is a fairly convenient alternative to the so-called “LUT” method, where using the Sprint-Layout program, a printer and the same PCB, you can assemble almost any circuit. So, beginners should still first master a simpler option, which is much simpler and, most importantly, “forgiving of mistakes” and also does not require a soldering station.

Having simplified the original diagram a little, I decided to redraw it:

I know that on the diagrams the transistor and stabilizer are not indicated that way, but it’s easier for me, and it will be clearer for you. And if, like me, you managed to take care of stabilization, then you need an even simpler scheme:

The same thing, only without using the KREN8B stabilizer.

R3 - 10K Ohm
R2 - 51K Ohm
R1 - from 50K to 100K Ohm (the resistance of this resistor can control the speed of LED ignition).
C1 - from 200 to 400 μF (you can choose other containers, but you should not exceed 1000 μF).
At that time I needed two soft ignition boards:
- for the already made highlighting of the legs.
- for smooth ignition of the dashboard.

Since I had already taken care of stabilizing the LEDs illuminating my legs a long time ago, Krenka was no longer needed in the ignition circuit.

Smooth ignition scheme without stabilizer.

For such a circuit, I used only 1.5 sq cm of circuit board, which costs only 60 rubles.

Smooth ignition circuit with voltage stabilizer.

Dimensions 25 x 10 mm.

The advantages of this circuit are that the connected load depends only on the capabilities of the power supply (car battery), and on the IRF9540N field-effect transistor, which is very reliable (it makes it possible to connect a 140W load through itself at a current of up to 23A (information from the Internet). The circuit can withstand 10 meters of LED strip, but then the transistor will have to be cooled, fortunately in this design you can attach a radiator to the field device (which of course will lead to an increase in the circuit area).

During the first testing of the circuit, a short video was shot:

Initially, R1 was rated at 60K Ohm and I didn’t like the fact that ignition to full brightness took about 5-6 seconds. Subsequently, another 60K Ohm resistor was soldered to R1 and the ignition time decreased to 3 seconds, which was just right for illuminating the legs .

And since the ignition circuit for illuminating the legs had to be connected to a break in the main power circuit, without thinking long about how to insulate it, I simply stuffed it into a piece of the bicycle inner tube.

In some cases, it is necessary to implement a circuit for smoothly turning on or off an LED. This solution is especially in demand in organizing design solutions. To implement the plan, there are two solutions. The first is to buy a ready-made ignition unit in a store. The second is making a block with your own hands. In the article, we will find out why it is worth resorting to the second option, and also analyze the most popular schemes.

Buy or make it yourself?

If you need it urgently or don’t have the desire or time to assemble a block for smooth switching on of LEDs with your own hands, then you can buy a ready-made device in a store. The only negative is the price. The cost of some products, depending on the parameters and manufacturer, can exceed several times the cost of a device made by yourself.

If you have the time and especially the desire, then you should pay attention to long-developed and time-tested schemes for smoothly turning on and off LEDs.

What do you need

In order to assemble a circuit for smooth ignition of LEDs, first of all, you will need a small set of radio amateurs, both skills and tools:

• soldering iron and solder;
• textolite for the board;
• body of the future device;
• a set of semiconductor devices (resistors, transistors, capacitors, LEDs, diodes, etc.);
• desire and time;

As you can see from the list, nothing special or complicated is required.

The Basics of Soft Start

Let's start with the basics and remember what an RC circuit is and how it is related to the smooth ignition and decay of the LED. Look at the diagram.

It contains only three components:

• R – resistor;
• C – capacitor;
• HL1 – backlight (LED).

The first two components make up the RC circuit (the product of resistance and capacitance). Increasing the resistance R and capacitance C of the capacitor increases the ignition time of the LED. When decreasing, the opposite is true.

We will not delve into the basics of electronics and consider how physical processes (more precisely, current) occur in this circuit. It is enough to know that it underlies the operation of all smooth ignition and extinction devices.

The considered principle of RC delay underlies all solutions for smooth turning on and off of LEDs.

Schemes for smooth switching on and off of LEDs

There is no point in disassembling cumbersome circuits, because... Most problems can be solved by simple devices operating on elementary circuits. Let's consider one of these schemes for smoothly turning on and off LEDs. Despite its simplicity, it has a number of advantages, high reliability and low cost.

Consists of the following parts:

• VT1 – field effect transistor IRF540;
• C1 – capacitor with a capacity of 220 mF and a voltage of 16V;
• R1, R2, R3 – resistors with a nominal value of 10, 22, 40 kOm, respectively;
• LED – light-emitting diode.

Operates from a voltage of 12 Volts according to the following algorithm:

1. When the circuit is connected to the power circuit, current flows through R2.
2. At this time, C1 gains capacity (charges), which ensures the gradual opening of the field switch VT
3. Increasing gate current (pin 1) flows through R1, and causes the field drain VT to gradually open
4. The current goes to the source of the same field switch VT1 and then to the LED.
5. The LED gradually increases its light emission.

The LED dims when the power is removed. The principle is the opposite. After turning off the power, capacitor C1 begins to gradually transfer its capacitance to resistances R1 and R2.

The discharge rate, and thus the smooth decay rate of the LED, can be adjusted by the nominal resistance R3. Experiment to understand how the rating affects the speed of LED ignition and decay. The principle is the following - higher resistance, slower attenuation, and vice versa.

The main element is the field-effect n-channel MOSFET transistor IRF540, all other semiconductor devices play an auxiliary role (piping). It is worth noting its important characteristics:

• drain current: up to 23 Amperes;
• polarity: n;
• drain-source voltage: 100 Volts.

More detailed information, including current-voltage characteristics, can be found on the manufacturer’s website in the datasheet.

Improved version with the ability to customize the time

The option discussed above assumes the use of a device without the ability to adjust the ignition time and LED attenuation. And sometimes it is necessary. To implement it, you just need to supplement the circuit with several elements, namely R4, R5 - adjustable resistances. They are designed to implement the function of adjusting the time of complete switching on and switching off the load.

The considered schemes of smooth ignition and decay are perfect for implementing designer lighting in a car (trunk, doors, foot area of ​​front passengers).

Another popular scheme

The second most popular scheme for smoothly turning on and off LEDs is very similar to the two discussed, but they are very different in operating principle. Switching on is controlled by minus.

The circuit has been widely used in places where one part of the contacts is connected to the negative and the other to the positive.

Differences between the scheme and those discussed earlier. The main difference is a different transistor. The field switch must be replaced with a p-channel one (the markings are shown in the diagram below). You need to “turn over” the capacitor, now the plus of the capacitor will go to the source of the transistor. Do not forget, the modified version has power with reverse polarity.

Video

For an in-depth understanding of everything that happens in the considered options, we suggest watching an interesting video, the author of which, using an electronic circuit design program, gradually shows the principle of smooth switching on and off of an LED in different options. After carefully watching the video, you will understand why you must use a transistor.

Conclusion

The solutions considered are the most popular and in demand. On the Internet, on forums, there are big discussions about the simplicity and low functionality of these schemes, but practice has shown that in everyday life their functionality is fully sufficient. A big plus of the considered solutions for turning on and off LEDs is their ease of manufacture and low cost. It will take no more than 3-7 hours to develop a ready-made solution.

Do-it-yourself smooth switching on and dimming of LEDs

What's happened smooth start, or otherwise ignition LEDs I think they all represent.

Let's look at it in detail do-it-yourself smooth switching on of LEDs.

The LEDs should not light up immediately, but after 3-4 seconds, but initially not blink or light up at all.

Device diagram:

Components:

■ Transistor IRF9540N
■ Transistor KT503
■ Rectifier diode 1N4148
■ Capacitor 25V100µF
■ Resistors:
- R1: 4.7 kOhm 0.25 W
- R2: 68 kOhm 0.25 W
- R3: 51 kOhm 0.25 W
- R4: 10 kOhm 0.25 W
■ One-sided fiberglass and ferric chloride
■ Screw terminal blocks, 2 and 3 pins, 5 mm

You can change the ignition and decay time of the LEDs by selecting the value of resistance R2, as well as selecting the capacitance of the capacitor.

There are many ways to cut PCB: with a hacksaw, metal scissors, using an engraver, and so on.

Using a utility knife, I made grooves along the marked lines, then sawed them out with a hacksaw and sharpened the edges with a file. I also tried using metal scissors - it turned out to be much easier, more convenient and dust-free.

Next, sand the workpiece under water with P800-1000 grit sandpaper. Then we dry and degrease the surface of the board with 646 solvent using a lint-free cloth. After this, it is not advisable to touch the surface of the board with your hands.

To do this, when printing in the program, at the top left in the “layers” section, uncheck unnecessary boxes. Also, when printing, in the printer settings we set high definition and maximum image quality. Using masking tape, glue a glossy magazine page/glossy photo paper (if their size is smaller than A4) onto a regular A4 sheet and print our diagram on it. I tried using tracing paper, glossy magazine pages and photo paper. It is most convenient, of course, to work with photographic paper, but in the absence of the latter, even magazine pages will do just fine. I don’t recommend using tracing paper - the design on the board is printed very poorly and will turn out unclear.

Now we warm up the textolite and attach our printout. Then use an iron with good pressure to iron the board for several minutes.

Now let the board cool completely, then put it in a container of cold water for a few minutes and carefully remove the paper from the board. If it doesn’t come off completely, then roll it up slowly with your fingers.

Then we check the quality of the printed tracks, and touch up the bad places with a thin permanent marker.

Using double-sided tape, glue the board onto a piece of foam plastic and place it in a ferric chloride solution for several minutes. The etching time depends on many parameters, so we periodically remove and check our board. We use anhydrous ferric chloride, dilute it in warm water according to the proportions indicated on the package. To speed up the etching process, you can periodically shake the container with the solution.

After the unnecessary copper has been removed, we wash the board in water. Then, using a solvent or sandpaper, remove the toner from the tracks.

Then you need to drill holes for mounting the board elements. To do this, I used a drill (engraver) and drills with a diameter of 0.6 mm and 0.8 mm (due to the different thickness of the legs of the elements).

Next you need to tin the board. There are many different ways, I decided to use one of the simplest and most accessible. Using a brush, we lubricate the board with flux (for example LTI-120) and tin the tracks with a soldering iron. The main thing is not to keep the soldering iron tip in one place, otherwise the tracks may come off due to overheating. We take more solder onto the tip and move it along the path.

Now we solder the necessary elements according to the diagram. For convenience inSprintLayotI printed out a diagram with symbols on plain paper and, when soldering, checked the correct arrangement of the elements.

After soldering, it is very important to completely wash off the flux, otherwise there may be shorts between the conductors (depending on the flux used). First, I recommend thoroughly wiping the board with 646 solvent, and then rinsing it well with a brush and soap and drying it.

After drying, we connect the “constant plus” and “minus” of the board to the power supply (“control plus” is not touched), then instead of the LED strip we connect a multimeter and check if there is voltage. If at least some voltage is still present, it means there is a short somewhere, perhaps the flux was not washed off well.

Result:

I am satisfied with the work done, although I spent quite a lot of time. The process of making boards using the LUT method seemed interesting and uncomplicated to me. But, despite this, in the process of work I probably made all the mistakes that were possible. But, as they say, you learn from mistakes.

Such a board for smooth ignition of LEDs has a fairly wide range of applications and can be used both in a car (smooth ignition of angel eyes, instrument panels, interior lighting, etc.), and in any other place where there are LEDs and a 12V power supply. For example, in illuminating a computer system unit or decorating suspended ceilings.