Sunset dawn smooth ignition attenuation of LEDs scheme. Scheme of smooth ignition and attenuation of LEDs

How the circuit works:

The control "plus" enters through a 1N4148 diode and a 4.7 kΩ resistor to the base of the KT503 transistor. In this case, the transistor opens, and through it and the 68 kΩ resistor, the capacitor begins to charge. The voltage on the capacitor gradually increases, and then through a 10 kΩ resistor it enters the input of the IRF9540 field effect transistor. 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 IRF9540 field effect transistor through a 51 kΩ resistor. After the end of the process of discharging the capacitor, the circuit stops consuming current and goes into standby mode. The current consumption in this mode is negligible.

Scheme with a control minus:

IRF9540N pinout marked

Scheme with control plus:

IRF9540N and KT503 pinout marked

This time I decided to make the circuit using the LUT method (laser-ironing technology). I did this for the first time in my life, I will say right away that there is nothing complicated. For work we need: a laser printer, glossy photo paper (or a page of a glossy magazine) and an iron.

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 kΩ 0.25 W
- R4: 10 kΩ 0.25 W
One-sided fiberglass and ferric chloride
Screw terminals, 2- and 3-pin, 5 mm

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

JOB:
?????????????????????????????????????????
?one? In this post I will show in detail how to make a board with a control plus. A board with a control minus is made in the same way, even a little simpler due to the smaller number of elements. We mark the borders of the future board on the textolite. We make the edges a little more than the pattern of the tracks, and then cut them out. There are many ways to cut textolite: with a hacksaw, metal scissors, using an engraver, and so on.

With the help of a clerical knife, I made grooves along the marked lines, then sawed out with a hacksaw and filed the edges with a file. I also tried to use scissors for metal - it turned out to be much easier, more convenient and without dust.

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

2? Next, using the SprintLayot program, we open and print the diagram on a laser printer. It is necessary to print only a layer with tracks without designations. To do this, in the program, when printing at the top left in the “layers” section, uncheck unnecessary checkboxes. Also, when printing in the printer settings, we set high definition and maximum image quality. I uploaded the program and the schemes slightly modified by me for you on Yandex.Disk.

Using masking tape, glue a page of a glossy magazine / glossy photo paper (if their dimensions are 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, the pages of the magazine will fit perfectly. I don’t advise using tracing paper - the drawing on the board was printed very poorly and will turn out to be fuzzy.

3? Now we warm up the textolite and apply our printout. Then, with an iron with a good pressure, iron the board for several minutes.

Now we let the board cool completely, after which we lower it into a container with cold water for a few minutes and carefully get rid of the paper on the board. If it does not completely tear off, then roll it slowly with your fingers.

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

4? Using double-sided tape, glue the board onto a piece of foam and place it in a solution of ferric chloride for several minutes. The etching time depends on many parameters, so we periodically take out and check our board. We use anhydrous ferric chloride, we 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 etched, we wash the board in water. Then, using a solvent or sandpaper, we clean the toner from the tracks.

5? Then you need to drill holes for mounting the board elements. For 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).

6? Next, you need to irradiate the board. There are many different ways, I decided to use one of the simplest and most affordable. Using a brush, lubricate the board with a flux (for example, LTI-120) and use a soldering iron to tin the tracks. The main thing is not to keep the soldering iron tip in one place, otherwise the tracks may break off when overheated. We take more solder on the sting and lead them along the path.

7? Now we solder the necessary elements according to the scheme. For convenience, in SprintLayot, I printed out a diagram with symbols on plain paper and checked the correct position of the elements when soldering.

eight? After soldering, it is very important to completely wash off the flux, otherwise there may be short pieces between the conductors (depending on the flux used). First, I recommend that you thoroughly wipe the 646 board with a solvent, and then rinse well with a brush with soap and dry.

After drying, we connect the “permanent plus” and “minus” of the board to the power supply (“we don’t touch the control plus”), 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 that it is short somewhere, the flux may have been washed off badly.

PHOTO:

Removed the board in heat shrink

VIDEO:

?????????????????????????????????????????
I T O G:
?????????????????????????????????????????
I am satisfied with the work done, although it took a lot of time. The process of manufacturing boards using the LUT method seemed interesting and simple 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 your mistakes.

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

Dimmer for car LED lighting.
Scheme of smooth ignition of LEDs.

Many car enthusiasts convert their car dashboard lighting from conventional incandescent bulbs to LEDs, and often, especially when using super-bright ones, the tidy shines like a Christmas tree and hurts the eyes with a bright glow, which requires the use of an additional device with which you can adjust the brightness level , as they say, to your taste. In general, there are two methods of regulation, this is analog regulation, which consists in changing the constant current level of the LED, and PWM regulation, that is, periodically turning on and off the current through the LED for adjustable periods of time. With PWM adjustment, the pulse frequency must be at least 200 Hz, otherwise the flickering of the LEDs will be noticeable to the eye. Below is a schematic diagram of the simplest block implemented on the NE555 timer chip, the domestic analogue of which is KR1006VI1, this microcircuit generates pulse-width control signals.

The brightness level of the backlight is regulated by a variable resistor with a nominal value of 50 kOhm, that is, this resistor changes the duty cycle of the control pulses. An N-channel field-effect transistor IRFZ44N is used as a regulating element, which can be replaced, for example, with an IRF640 or similar.

It probably makes no sense to make a list of the elements used, there are not so many of them in the circuit, so let's move on to the consideration of the printed circuit board.

The printed circuit board was developed in the Sprint Layout program, the view of the board of this format is as follows:

Photo view of the PWM controller board LAY6 format:

Many people have a desire to add the effect of smooth ignition to the regulator circuit, and a simple scheme widely used on the Internet will help us with this:

On the printed circuit board, we placed both of the above circuits, and the regulator circuit, and the smooth ignition circuit. LAY6 board format looks like this:

Photo view of LAY6 format:

Foil textolite for the board is one-sided, size 24 x 74 mm.

To set the desired ignition and decay time, play with the values ​​​​of the resistors indicated on the printed circuit board with asterisks, this time also depends on the value of the electrolytic capacitance in the ignition circuit located above the LED output socket (As the value of the capacitor increases, the time will increase).

Please note that a P-channel MOSFET is used in the soft ignition circuit. The pinout of the transistors is shown below:

In addition to the article, we give another example of a circuit with a dimmer and smooth ignition of the car dashboard LEDs:

The size of the archive with the materials of the article is 0.4 Mb.

In some cases, it is required to implement a circuit for smoothly turning on or off the light-emitting diode (LED). This solution is especially in demand in the organization of design solutions. To implement the plan, there are two ways to solve it. The first is the purchase of a ready-made ignition unit in a store. The second is making a block with your own hands. As part of the article, we will find out why it is worth resorting to the second option, and also analyze the most popular schemes.

Buy or do it yourself?

If you urgently need or don’t have the desire and time to assemble a soft turn on LED block with your own hands, then you can buy a finished device in the store. The only downside is the price. The cost of some products, depending on the parameters and the manufacturer, may be several times higher than the cost of a do-it-yourself device.

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

What do you need

In order to assemble a smooth ignition circuit for LEDs, you first 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 and complicated is required.

The basis of soft start basics

Let's start with elementary things 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 consists of only three components:

• R is a resistor;
• C - capacitor;
• HL1 - backlight (LED).

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

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

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

Schemes of smooth switching on and off of LEDs

It makes no sense to disassemble bulky circuits, because to solve most problems, simple devices operating on elementary circuits cope. 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 - LED.

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

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

The attenuation of the LED occurs when the power is removed. The principle is reversed. After the power is turned off, the capacitor C1 begins to gradually give up its capacitance to the resistances R1 and R2.

The discharge rate, and thus the rate of smooth fading of the LED, can be controlled by the value of the resistance R3. Experiment to understand how the value affects how quickly the LED lights up and fades out. The principle is the following - higher resistance, slower attenuation, and vice versa.

The main element is the field 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 CVC, can be found on the manufacturer's website in the datasheet.

Improved version with the ability to set the time

The option considered above assumes the use of a device without the possibility of adjusting the time of ignition and attenuation of the LED. And sometimes it's necessary. For implementation, 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 full switching on and off of the load.

The considered schemes for smooth ignition and attenuation are perfect for implementing designer lighting in a car (trunk, doors, front passenger footwell).

Another popular pattern

The second most popular scheme for smoothly turning LEDs on and off is very similar to the two considered, but they differ greatly in how they work. Switching on is controlled by minus.

The scheme was widely used in those places where one part of the contacts closes on the minus, and the other on the plus.

Differences of the scheme from those considered earlier. The main difference is a different transistor. The field worker must be replaced with a p-channel one (marking is indicated in the diagram below). It is necessary to “flip” the capacitor, now the plus of the conder will go to the source of the transistor. Do not forget, the modified version has a power supply 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 the electronic circuit design program, gradually shows the principle of operation of the smooth turning on and off of the LED in different options. After carefully watching the video, you will understand why it is necessary to use a transistor.

Conclusion

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

Smooth turning on the LED using PWM (PWM) on the Arduino will be discussed on this page. Consider how to connect an LED, let's look at what PWM (Pulse Width Modulation) is. We will also take a closer look at the cycle for in the C++ programming language, which is used to repeat statements enclosed in a construct (statements that are inside curly braces in a sketch).

Smooth turning on the LED on Arduino

To remember what Arduino is, we use a simple sketch to smoothly turn on the LED. You can use a for loop for this. The header of this construction consists of three parts: for (initialization; condition; increment) - initialization is executed once, then the condition is checked condition, if the condition is true, then the increment is performed increment and the loop repeats as long as the condition is true.

In the above example, we will smoothly change the brightness of the LED using PWM, the LED will smoothly flare up and then fade out. This example can be used for decorative lighting in a room with LEDs or a night lamp controlled by a remote control. Connect an LED to analog port Pin6 and upload the following sketch.

LED control with Arduino PWM

For the lesson we need the following details:

• board Arduino Uno / Arduino Nano / Arduino Mega;
• bread board;
• 1 LED and 1 220 Ohm resistor;
• wires "father-father" and "father-mother".

Scheme. Smooth blinking LED on Arduino

Sketch of smooth turning on of the LED from Arduino

#define LED_PIN 6 // set a name for Pin6 void setup()(pinMode(LED_PIN, OUTPUT); // initialize pin6 as output) void loop() ( // soft turn on the LED // initial value on Pin6 i=0 if i<=255, то прибавляем к i единицу for (int i=0;i<=255;i++) { analogWrite (LED_PIN, i); delay (5); } //smooth fading of the LED // initial value on Pin6 i=255, if i>=255, then subtract one from i for (int i=255;i>=0;i--) ( analogWrite (LED_PIN, i); delay (5); // set a delay for the effect } }

Explanations for the code:

1. the for loop repeats as long as condition i is true<=255 или i>=0 ;
2. for the for loop, the following values ​​must be written in parentheses - (initialization; condition; increment) ;
3. the for loop construct must be placed between curly braces ( ) .

Greetings to all beginner electronics engineers and lovers of radio engineering and those who like to do something with their own hands. In this article I will try to kill two birds with one stone: I will try to tell you how to make a printed circuit board of excellent quality yourself, which will not differ in any way from the factory counterpart, thus we will do it. This device can be used in a car to connect LEDs. For example, as in .

For work we need:

• Transistors - IRF9540N and KT503;
• Capacitor for 25 V 100 pF;
• Diode rectifier 1N4148;
• 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.
• Screw terminals, 2- and 3-pin, 5 mm
• One-sided textolite and FeCl3 - ferric chloride

Working process.

First of all, we need to prepare the board. To do this, we mark the conditional boundaries of the board on the textolite. We make the edges of the board a little more than a track pattern. Once the edges of the borders have been marked, you can start cutting. You can cut with scissors for metal, and if they are not at hand, you can try to cut with a clerical knife.

After the board has been cut out, it needs to be sanded. To do this, sand the board under water with sandpaper with a grain size of P800-1000. Next, dry and degrease the surface with the 646th solvent. After that, touching the board is not recommended.

Next, download the program, which is at the end of the article, SprintLayout and use it to open the board layout and print it on a laser printer on glossy paper. It is important that the printer settings are set to high definition and high image quality when printing.

Then it will be necessary to heat the prepared board with an iron and attach our printout to it and iron the board thoroughly for several minutes.

Next, let the board cool down a bit, after which we lower it for a few minutes in a cup of cold water. The water will make it easy to peel the glossy paper off the board. If the gloss is not completely torn off, then you can simply roll the rest of the paper slowly with your fingers.

Then it will be necessary to check the quality of the tracks, if there is minor damage, then you can tint the bad places with a simple marker.

So, the preparatory stage is completed. Left . To do this, we put our board on double-sided tape and glue it on a small piece of foam and lower it into a solution of ferric chloride. To speed up the etching process, you can shake the cup with the solution.

After the excess copper is etched, it will be necessary to wash the board in water and use a solvent to clean the toner from the tracks.

It remains to drill holes. For our device, drills with a diameter of 0.6 and 0.8 mm were used.

It is important not to overheat the tracks otherwise you can damage them.

It remains to assemble our device. Previously, it is recommended to print the circuit with symbols on plain paper and, guided by it, place all the elements on the board.

After everything is soldered, it is necessary to completely clean the board from the flux. To do this, carefully wipe the board with the same 646 solvent and thoroughly wash with a brush and soap and dry.

After drying, we connect and check with the help of the performance of the assembly. To do this, we connect the "constant plus" and "minus" to the power supply, and instead of the LEDs, we connect a multimeter and check if there is voltage. If there is tension, it means that the flux is not completely confused.

As you can see, the board manufacturing process is not a very complicated process. This method of making a board is called LUT (laser-ironing technology). As mentioned above, this assembly can be used for ( , , , ), or in any other places where LEDs and 12 volt power are used -

Thank you all for your attention! I will be happy to answer all your questions!

Good luck on the road!!!

NECESSARILY!!!

Devices whose actions and properties are little known to you, especially homemade ones, connect through fuses.