Projects, schemes, drawings
Soft start of incandescent lamps with your own hands. Smooth switching on of incandescent lamps on a triac

Soft start of incandescent lamps with your own hands. Smooth switching on of incandescent lamps on a triac

In any electrical circuit, each sensor or element performs a specific job. In this case, these are devices that provide a smooth start of various light sources. It is important to understand that the highest overloads bulbs experience during their start-up. Since after applying voltage to them, the temperature and voltage change greatly, which jumps from 0 to 220 volts. In order to reduce the load, various sensors and devices are used that are built into the circuit.

Electric incandescent lamps: types

Despite the fact that at present it has become quite popular to use halogen, fluorescent and LED lamps (LEDs) in various lighting devices, a huge part of the devices work on the basis of incandescent lamps. These light sources are divided into types according to various parameters.

Main parameters:

Purpose;
Specifications (device).

By appointment, incandescent lamps can be divided into two types. For work in various household lighting devices, and in the car. As a rule, in household lighting devices (in an apartment), incandescent lamps of 220 V, 24 V and 12 Volts are used. In cars (for headlights), only low-voltage light sources are used.

Note! Currently, incandescent lamps are the cheapest light sources.

The technical characteristics of the lamps include various indicators. For example, Lamps are classified according to the shape of the bulb. There are spherical, cylindrical and tubular flasks. Flasks are matte, transparent and mirror.

It is worth noting that the main technical characteristics of the lamps include its power, which varies between 25 - 150 watts.

The operating voltage of the lamps is (depending on the type of lamp) from 12 to 230 volts. Incandescent lamps also differ in the type of base. For example, the base can be threaded or pin-shaped, with one or two pins.

Threaded plinths are distinguished by diameter and marked as follows: (E 14) - plinth diameter 14 mm, (E 27) and (E40).

Slow (smooth) turning on of incandescent lamps

Soft start or ignition of incandescent lamps, easy to do with your own hands. There is more than one scheme for this. In some cases, after turning off the voltage supply, the lamps are also smoothly turned off.

Basic schemes:

Thyristor;
On a triac;
Using microchips.

The thyristor connection circuit consists of several main elements. Diode, in the amount of four pieces. The diodes in this circuit form a diode bridge. To ensure the load, use incandescent bulbs.

A thyristor and a shifting chain are connected to the rectifier arms. In this case, a diode bridge is used, as this is due to the operation of the thyristor.

After the start is made, and voltage is applied to the unit, electricity passes through the filament of the lamp and is fed to the diode bridge. Further, with the help of a thyristor, the electrolyte capacity is charged.

After the required voltage is reached, the thyristor opens and current from the lamp begins to flow through it. Thus, there is a smooth start of the incandescent lamp.

Note! As constituent elements in various schemes, parts different from each other can be used. Such as: mac 97 a 6, m 51957 b, av 2025 p, mc908 qy 4 pce, ba 8206 ba 4, ba 3126 n, 20 wz 51, 4n 37.

The circuit using a triac is simple, since triacs are the power key in the circuit. To adjust the current of the control electrode, use a resistor. The response time is set using several circuit elements, a resistor and a capacitance, powered by a diode.

To operate several powerful incandescent lamps, various microcircuits are used. This is achieved by adding an additional power triac to the circuit. It is worth noting that these circuits work not only with conventional lamps, but also with halogen ones.

Scheme for smooth ignition of LEDs on field workers

There are a huge number of circuits for smooth ignition of LEDs. Some are complex and may consist of costly parts. But you can also assemble a simple circuit that will ensure the correct and long operation of this light source.

For assembly you will need:

Field effect transistor - IRF 540;
R1 - resistance with a nominal value of 10 kOhm;
R2 - resistance from 30 kOhm to 68 kOhm;
R3 - resistance from 20 to 51 kOhm;
Capacitor with a capacitance of 220 microfarads.

Since the resistance R1 (regulator) sets the gate current, then for this transistor, a resistance of 10 kOhm is sufficient. For the smooth start of the LEDs, the resistance R2 is responsible, then its nominal resistance must be selected in the range from 30 to 68 kOhm. This setting depends on preference.

The slow decay of the LEDs provides resistance R3, so its value should be from 20 to 51 kOhm. The capacitance parameters of the capacitor vary from 220 to 470 microfarads.

Note! The limit voltage of the capacitor must be at least 16 volts.

The power parameters of a field-effect transistor include voltage and current. The voltage on the contacts reaches 100 Volts, and the power is up to 23 Amps.

After voltage is applied to the circuit through the switch, the current flowing through the resistor R2 begins to charge the capacitor. Since charging takes a certain amount of time, in this case, the transistor is smoothly opened.

When the power supply is turned off, the capacitor smoothly gives charge to the resistances, which allows you to turn off the LEDs smoothly.

Smooth ignition of halogen lamps in the car

In various cars, not only mechanical parts are subjected to overloads, they are also tested by the elements that make up electrical circuits. Therefore, in order to increase the duration of the equipment, various devices are included in the circuits to ensure the smooth start of the lamps.

The main parameters for installing soft ignition units:

Vibration;
Temperature and electrical fluctuations.

Lamps with increased light output, according to the device, are very sensitive to minor voltage drops in the electrical circuit. These drops vary from 10 to 13 volts.

Note! Most halogen bulbs fail during startup. Since the voltage drop is from 0 to 13 volts.

The best solution would be to install a soft ignition unit. Installation is possible on the dipped and main beam headlights. It is worth noting that this relay plays the role of protecting the light source.

It is important to understand that installing one unit on the lamps responsible for the head light is not recommended, since if the unit fails, both lamps will stop working. Installation of one block, possible sense for additional lighting.

The block is made in the form of a relay equipped with five contacts for connection. The main elements of the block are the relay contacts (power section) and the control unit.

The operation of this block is carried out as follows. After the thirtieth contact is energized, the block that controls the circuit connects the key in parallel. Further, the key, using incremental pulses, begins to close contacts 30 and 87 between themselves.

After two seconds of operation, these contacts are completely closed, after which the control unit energizes the relay. Next, contacts 30 and 87 open and contacts 30 and 88 close. If you apply voltage to the additional 86 contact, then when the headlights are turned off, the halogen lamps will slowly fade.

Scheme for smooth switching on incandescent lamps for 220 V (video)

Now you understand that embedding additional elements into various electrical circuits can not only ensure their smooth start, but also act as a protective mechanism that will ensure long-term operation of the lamps.

When designing amplifier power supplies often there are problems that are in no way connected with the amplifier itself, or are a consequence of the applied element base. So in power supplies transistor amplifiers of high power, it often becomes a problem to implement a smooth switching on of the power supply, that is, to ensure a slow charge of electrolytic capacitors in the smoothing filter, which can have a very significant capacity and, without taking appropriate measures, will simply disable the rectifier diodes at the moments of switching on.

In the power supplies of tube amplifiers of any power, it is necessary to provide a delay in the supply high anode voltage before the lamps warm up to avoid premature depletion of the cathode and, as a result, a significant reduction in the lamp life. Of course, when using a kenotron rectifier, this problem is solved by itself. But in the case of using a conventional bridge rectifier with an LC filter, you cannot do without an additional device.

Both of the above problems can be solved by a simple device that can be easily built into both a transistor and tube amplifier.

Device diagram.

The schematic diagram of the soft start device is shown in the figure:

Zoom on click

The alternating voltage on the secondary winding of the transformer TP1 is rectified by the diode bridge Br1 and stabilized by the integral stabilizer VR1. Resistor R1 provides a smooth charge of capacitor C3. When the voltage on it reaches the threshold value, the transistor T1 will open, as a result of which the Rel1 relay will operate. Resistor R2 discharges capacitor C3 when the device is turned off.

Inclusion options.

The relay contact group Rel1 is connected depending on the type of amplifier and the organization of the power supply.

For example, to ensure a smooth charge of capacitors in the power supply transistor power amplifier, the presented device can be used to shunt the ballast resistor after the capacitors are charged in order to eliminate power losses on it. A possible inclusion option is shown in the diagram:

The fuse and ballast resistor ratings are not indicated, as they are selected based on the power of the amplifier and the capacitance of the smoothing filter capacitors.

In a tube amplifier, the presented device will help organize a feed delay high anode voltage before the lamps warm up, which can significantly extend their service life. A possible inclusion option is shown in the figure:

The delay circuit here is turned on simultaneously with the filament transformer. After the lamps have warmed up, the Rel1 relay will turn on, as a result of which the mains voltage will be applied to the anode transformer.

If your amplifier uses one transformer both to power the filament circuits of the lamps and for the anode voltage, then the relay contact group should be transferred to the secondary winding circuit anode voltage.

Elements of the turn-on delay circuit (soft start):

Fuse: 220V 100mA,
Transformer: any low-power with an output voltage of 12-14V,
Diode bridge: any small-sized with parameters 35V / 1A and above,
Capacitors: C1 - 1000uF 35V, C2 - 100nF 63V, C3 - 100uF 25V,
Resistors: R1 - 220 kOhm, R2 - 120 kOhm,
Transistor: IRF510,
Integral Stabilizer: 7809, LM7809, L7809, MC7809 (7812),
Relay: with winding operating voltage 9V (12V for 7812) and contact group of appropriate power.

Due to the low current consumption, the stabilizer chip and the field effect transistor can be mounted without radiators.

However, someone may have the idea to abandon the extra, albeit small-sized, transformer and power the delay circuit from the filament voltage. Given that the standard heating voltage is ~ 6.3V, you will have to replace the L7809 stabilizer with the L7805 and use a relay with a winding operating voltage of 5V. Such relays usually consume significant current, in which case the microcircuit and transistor will have to be equipped with small heatsinks.

When using a relay with a 12V winding (somehow more common), the integrated stabilizer microcircuit should be replaced with a 7812 (L7812, LM7812, MC7812).

With the values of resistor R1 and capacitor C3 indicated in the diagram delay time inclusion is of the order 20 seconds. To increase the time interval, it is necessary to increase the capacitance of the capacitor C3.

The article was prepared based on the materials of the magazine "AudioXpress"

Free translation of the Editor-in-Chief of Radio Gazeta.

On the Internet, there are many schemes for smooth ignition and attenuation of 12V powered LEDs that you can do yourself. All of them have their advantages and disadvantages, differ in the level of complexity and quality of the electronic circuit. As a rule, in most cases it makes no sense to build bulky boards with expensive parts. In order for the LED crystal to smoothly gain brightness at the moment of switching on and also smoothly go out at the moment of switching off, one MOS transistor with a small strapping is enough.

Scheme and principle of its operation

Let's consider one of the simplest options for the smooth switching on and off of LEDs controlled by a positive wire. In addition to the simplicity of execution, this simplest circuit has high reliability and low cost. At the initial moment of time, when the supply voltage is applied, current begins to flow through the resistor R2, and the capacitor C1 is charged. The voltage on the capacitor cannot change instantly, which contributes to the smooth opening of the transistor VT1. Increasing gate current (pin 1) passes through R1 and leads to an increase in the positive potential at the drain of the FET (pin 2). As a result, the load from the LEDs is smoothly turned on.

When the power is turned off, the electrical circuit breaks along the "control plus". The capacitor begins to discharge, giving energy to the resistors R3 and R1. The discharge rate is determined by the value of the resistor R3. The greater its resistance, the more accumulated energy will go into the transistor, which means that the decay process will last longer.

To be able to adjust the time of full on and off of the load, trimming resistors R4 and R5 can be added to the circuit. At the same time, for correct operation, it is recommended to use the circuit with resistors R2 and R3 of a small value.
Any of the circuits can be independently assembled on a small board.

Circuit elements

The main control element is a powerful n-channel MOS transistor IRF540, the drain current of which can reach 23A, and the drain-source voltage is 100V. The considered circuit solution does not provide for the operation of the transistor in limiting modes. Therefore, he does not need a radiator.

Instead of IRF540, you can use the domestic analogue of KP540.

The resistance R2 is responsible for the smooth ignition of the LEDs. Its value should be in the range of 30-68 kOhm and is selected during the setup process based on personal preferences. Instead, you can install a compact tuning multi-turn resistor at 67 kOhm. In this case, you can adjust the ignition time with a screwdriver.

The resistance R3 is responsible for the smooth fading of the LEDs. The optimal range of its values is 20–51 kOhm. Instead, you can also solder a trimmer to adjust the decay time. In series with trimming resistors R2 and R3, it is desirable to solder one constant resistance of a small value. They will always limit the current and prevent a short circuit if the trimmers are turned to zero.

The resistance R1 serves to set the gate current. For the IRF540 transistor, a rating of 10 kOhm is sufficient. The minimum capacitance of capacitor C1 should be 220 uF with a voltage limit of 16 V. The capacitance can be increased to 470 uF, which will simultaneously increase the time for full on and off. You can also take a capacitor for a higher voltage, but then you will have to increase the size of the printed circuit board.

minus control

The above translated schemes are great for use in a car. However, the complexity of some electrical circuits lies in the fact that some of the contacts close on the plus, and some - on the minus (common wire or case). To control the above circuit by minus power, it needs to be slightly modified. The transistor must be replaced with a p-channel one, for example IRF9540N. Connect the negative terminal of the capacitor to the common point of three resistors, and close the positive terminal to the source VT1. The modified circuit will be powered with reverse polarity, and the control positive contact will change to negative.

Where to install the protection unit?

Blocks are installed directly for each lamp individually. It is better to interfere with them in the cavity under, where the wiring is hidden. Since the block is small, it will fit anywhere. You can install them both independently, if you understand the electrician, and with the help of a specialist.

You can also use one block for several lamps. For example, if the ceiling has built-in lighting from a variety of lamps or a chandelier with plinths.

Before proceeding, you should thoroughly understand the device device in order to correctly identify possible malfunctions, and adhere to the standard procedure for carrying out repair work.

For soldering, it is possible to assemble a hot air station yourself at home. Find out how to do it. To operate such a tool, you need to be able to correctly.

Permissible installation option in a junction box. Usually powerful models are placed there, which will cover the whole circuit of electric lamps in the house. If you also have a transformer for lowering the power, then the unit should be the first in the circuit, that is, the main stream of 220 V is intended only for it. And after distribution to the entire private network.

Important! Place the appliances so that in case of replacement, repair, they can be easily reached.

It is better to avoid strong gluing with wallpaper, drywall (which is effectively placed into the ceiling) and plaster the place where the soft start unit is located.

Installation of the protection unit circuit and incandescent lamp

Connect the device to the circuit as follows:

the input of the protection unit is connected from the phase in front of the incandescent lamp (comes from the switch), it acts as an intermediary between the cable that feeds the lamp;
the output from the unit is connected to the other end of the cable, which leads directly to the lamp.

When you turn on the incandescent bulb, you can observe for 3 seconds how the light from a bright flash is converted into a dim stream of light. This means that the block in the chain is running successfully.

If you measure the voltage at the input and output with an electronic multimeter, you can see the difference in the decrease in voltage.

There is nothing complicated in installing soft start blocks. Do not forget about safety when working with electrical circuits, as well as the correct calculation of power for the purchase of the device.

A short video about the features of the smooth switching on of 220 V incandescent lamps

Hello, dear readers of the site. Looking through the article about, I immediately remembered the long-established and well-established scheme for smoothly turning on and off the lighting, which was published in Radio magazine No. 10 1981, p. 54.

In the given design, when turned on, the light in 1.5 - 2 seconds smoothly lights up to the maximum, and when turned off, it goes out just as smoothly (as in a movie theater) in 1.5 - 2 minutes. This design is very cool in relation to a night light, sconce or chandelier, although only incandescent lamps should be used in lamps. It is very important that the use of the proposed scheme greatly increases the service life of incandescent lamps, since they have a characteristic feature that they burn out very often at the time of normal switching on.

I repeated this circuit with the same resistor values, but instead of germanium transistors and diodes, I used silicon ones.

A thyristor was used as a control element. VD5 PCR406J from a Chinese Christmas tree garland, so the dimensions of the printed circuit board turned out to be 40x30mm, which is ideal for the size of the box from the garland control.

In order for the circuit to work in the entire voltage range from 0 to 220 V, a diode bridge is used VD6 – VD9, composed of domestic rectifier diodes KD105V. Diodes in junctions VD1 – VD3 I used KD522V, but you can also use an imported analogue 1N4148. Power of quenching resistor R7 reduced to 0.5W, and the value increased to 68 kOhm, all other resistors MLT 0.125.

Increasing the value of the damping resistor R7 provides stabilization current to the zener diode VD4, the main load element of the circuit, within 10-15mA, which is its rated stabilization current. In this case, the circuit operates in normal mode without any heating of the resistor. R7.

The supply voltage after the quenching resistor corresponds to the stabilization voltage of the zener diode VD4(you can use zener diodes D814 with letter indices A - D and stabilization voltage 7 - 12 V). I have a stabilizer KS210B- a two-anode zener diode, when using which it is not necessary to observe the polarity of switching on, but when using a conventional zener diode, it is very important to observe the polarity, since if you make a mistake, there will be no voltage stabilization.

When repeating the circuit, the task was to use silicon-based transistors, and I also wanted to minimize the overall dimensions of the printed circuit board. In the above version, the circuit started up from half a turn, that is, I want to note that with proper installation and serviceability of the applied radio elements, everything should work right away.

The setting is minimal and consists only in the selection of capacitor values C1 And C2. Increasing the capacitance of the capacitor C1 leads to an increase in the time of smooth extinction of the lamps, and a decrease in capacitance C2 to increase the time of smooth ignition of the lamps. A table lamp with an incandescent lamp power of 40 W was used as a load.

I enclose the assembled and tested design in the photo, but this is a purely test option, since when creating your own design, you may have to use your ingenuity and adapt the circuit to your lamp. If the board is packed in a Christmas tree garland box, then it can be placed near the switch or hidden somewhere nearby. Four wires come out of the box - two to the new switch and two to the already installed one.

With a load power of up to 60 W, the proposed thyristor and diodes are quite satisfactory, but for power of 200 W or more, it is necessary to use a rectifier bridge and thyristor, designed for a higher current in accordance with the power of the lamp. In my first version, the load of the circuit was a chandelier with a total power of 360 W and D245 diodes and a KU202N thyristor were used, and no radiators were required. Now on sale there are many powerful diodes, as well as diode bridges, for example KBL406.

To use the installation to work with an already connected chandelier, you need two contacts of the diode bridge that go to the change (for the diode bridge, these conclusions are marked with the icon “ ~ ”), connect to the terminals of the switch, which must be in the open state, and also install an additional switch nearby that controls the operation of the circuit.

I want to say a little about the transistors used. Almost any transistor can work in the circuit. Of the domestic options, KT502, KT503, KT3102, KT3107 with any letter index are well suited. I have to save space involved VT1, VT4 — KT315 And VT3 KT361. The value of the gain of transistors does not really matter, although the transistor VT2 KT3107, which controls the operation of the pulse generator, is applied with a slightly higher gain h21e. It was put rather for reinsurance, but KT502 or KT361 should also work reliably.