Scheme of switching garlands on 12V relay transistors. Programmable garland switch

The proposed circuit was designed for use as a Christmas tree garland switch. However, this circuit can also be used for other purposes when periodic switching on of the load is required (automation systems, warning and alarm systems, etc.). This device is connected to a break in one of the wires going to the load, in this case a Christmas tree garland. Which, firstly, facilitates its operation, since only two wires are required to be connected to the device. Secondly, safety increases, since if these wires are shorted both outside and inside the device, a short circuit will not occur, the load will simply be constantly on. The proposed switch has two operating modes. The first is when the llamas of the garland periodically go out completely, the second is when the lamps do not go out completely, but their brightness decreases.

Scheme

Let's consider the operating principle of the circuit diagram of this device (Fig. 1). Using elements DD1.1 - DD1.6 of the k561ln2 microcircuit, a generator of rectangular pulses is assembled, the frequency of which is set by the value of resistor R1 and capacitor C2. In order to increase the output load capacity of the generator, its elements DD1.2 - DD1.6 are connected in parallel. When the generator output is at a high level, diode VD3 is locked, and thyristor VS1 connected to the diagonal of the bridge is open due to the current flowing through resistor R3 to its control electrode. As a result of this, the garland lamps are turned on. When the generator output goes low, diode VD3 opens and shorts the control electrode of thyristor VS1 to the cathode. The thyristor closes and the garland lamps go out.

If you close the contacts of switch SA1, then even with the thyristor VS1 closed, half-wave mains voltage will flow to the garland lamps through the diode VD8 and they will glow with a faint flickering light. That is, in this mode, the lamp circuits will not periodically go out completely, but their brightness will only decrease.

When thyristor VS1 is locked, the voltage flowing through resistor R2, stabilized by zener diode VD2 at 12 Volts, charges capacitor C1, and is used to power microcircuit DD1. And diode VD1 prevents capacitor C1 from discharging through resistor R2 when thyristor VS1 is open when the garland lamps are turned on.

Resistor R3 sets the current flowing through the control electrode of thyristor VS1; it should be selected with the highest possible resistance at which stable unlocking of thyristor VS1 is ensured in order to reduce the useless heating of this resistor. When replacing thyristor VS1 with a thyristor of another brand, for example, thyristors of the Ku202 series, which have a higher control electrode current, it may be necessary to reduce the value of resistor R3, increasing its power accordingly. It is not worth reducing the resistance of resistor R3 below 8 kOhm to avoid overloading the microcircuit.

Details

The DD1 k561ln2 microcircuit can be replaced with k562ln1 with appropriate correction of the printed circuit board, since these microcircuits do not have the same pin assignments. As diodes VD1, VD3, you can use CD102, CD103, CD521, CD522 with any letter index. Zener diode VD2 - ks191zh, ks210zh, ks212zh, ks213zh, ks508a. Diodes VD4 - VD8 - kd105, kd209 with any letter index. Capacitor C1 is k50-35 or similar imported, and C2 is type k10-17, k73-17 or similar imported. Switch SA1 of any type capable of withstanding the mains voltage and load current.

The arrangement of elements on the printed circuit board and its drawing are presented in Fig. 2 and Fig. 3, respectively. And the photo of the soldered printed circuit board is in Fig. 4.

The finished device was placed in a plastic electrical box. His photo is shown in Fig. 5. A domestically produced Christmas tree garland, consisting of 18 lamps of 13.5 Volts 0.16 Amperes, was connected to this switch. The frequency of switching on the garland can be changed by changing the value of resistor R1. The scheme was proposed by YRIT.

Since childhood, I have been interested in radio engineering, went to radio clubs, soldered simple toys, receivers...

In the photo above, one of my hand-made devices is intended for switching Christmas tree garlands. Absolutely everything is made by hand, from metal fasteners to control knobs carved from plexiglass.

You can connect four Christmas lights with a power of 400 watts to the device, i.e. in fact, you can solder your 4 garlands of about 100 2.5 volt bulbs, for a total of about 400 bulbs :)

A few years later, cheap Chinese garlands appeared on sale and I decided to make a full-fledged chain of light bulbs for my flasher from them. The light bulbs were re-soldered with normal domestic wires in such an order that the effect of running lights was created. In general, my flasher has 6 modes for switching garlands so that you can choose a flickering mode to suit every taste, and also set the speed of flickering of the garlands. You can see how I use my garland in the article about the Christmas tree.

The body of the device is made of plastic, I cut it out of an ordinary kitchen tray, then the body is covered with self-adhesive film. The cover can be easily removed, you just need to unscrew the four screws on the sides. Rubber feet are glued to the bottom; these are gaskets from plumbing fixtures.

Inside the box, everything is conveniently arranged, the radio components are located as far as possible from each other so as not to cause a short circuit. Perhaps the only drawback of my design is the lack of a ventilation grille, but over the years of use the device has never failed.

The flasher circuit is quite simple; most radio amateurs probably know this circuit; it has been published more than once in various magazines. The circuit does not require configuration and works immediately after installation. The circuit diagram uses four domestic integrated circuits and several other available parts. The only shortage is the control thyristors, but they can be easily replaced with analogues. I slightly modified the original circuit from the magazine by adding 4 transistors, 4 resistors and 4 LEDs to indicate operation on the front panel of the device. I also added a speed control for switching the garlands and a button for reversing the running lights.

The flasher has been serving faithfully for about 5 years now, and it’s unlikely that I’ll find something more perfect and so durable on sale.

Analogue circuits

Garland switch

Figure 1.1 - Garland switch

The diagram of the first switch is shown in Fig. 1. This device controls two garlands consisting of small-sized red and green LEDs, and is designed to decorate a small Christmas tree.

A symmetrical multivibrator is assembled on transistors VT1, VT2, the switching frequency of which is determined by the values ​​of resistors R1 - R4 and capacitors Cl, C2. For the ratings of these elements indicated in the diagram, the frequency is about 1 Hz. The collector circuits of the transistors include two garlands of LEDs HL1 - HL32. Diodes VD1, VD2 and resistors Rl, R4 are necessary to ensure recharging of capacitors C1 and C2. The power supply for the garland switch is made according to the circuit of a half-wave rectifier using a VD3 diode using a ballast capacitor C4 to dampen the voltage. Diode VD4 is necessary to recharge the capacitor at a positive wave (relative to the lower voltage in the network wire diagram), resistor R6 limits the current pulse when the device is connected to the network when the capacitor is discharged. Through resistor R5, capacitor C4 is discharged after the device is turned off from the network. Rectified voltage ripples are smoothed out by capacitor SZ. There is no zener diode in the power supply, and the voltage on the multivibrator elements is limited by the voltage on the turned on garland of LEDs, i.e. LEDs perform the function of zener diodes. Since at any moment one of the two garlands is necessarily turned on, the voltage on the capacitor SZ cannot exceed the voltage on the luminous garland.

The advantage of the scheme: ease of implementation.

Disadvantages of the circuit: low output power, the presence of only one garland switching mode.

This scheme is quite simple, but it also implements a fairly large number of lighting effects, such as “running shadow”, “running fire”, “paired switching on”, “alternating switching on and off”, etc.

Figure 1.2 - Automatic garland switch

The basis of the device is a four-bit shift register with parallel loading K555IR16. The register control unit consists of a K555IE7 binary counter and logical elements DD1.3 and DD3.1. The effect of “running lights” is achieved in one direction by simply shifting the code in the register, and in the opposite direction by parallel writing it to the register by one bit.

The master oscillator of the machine is assembled on elements DD1.1 and DD1.2. Pulse frequency 3-4Hz. It can be changed by selecting R1 AND C1. The machine can control not only LEDs, but also lamps powered from the network. To do this, they must be connected according to the following diagram.

Figure 1.3 - Connection diagram for lamps powered from the mains

Let's look at the operating features of this device. The inverting input of comparator DA2 receives sawtooth pulses with a frequency equal to double the network frequency. The non-inverting input of the comparator receives triangular pulses of infra-low frequency, which are generated by a generator assembled on the logic elements of the DD1 microcircuit. Elements D1.1, DD1.2 and resistors R10, R11 form a Schmitt trigger, which is part of the generator. Let's say that at the output of logic element DD1.3 there is a high level voltage, and capacitor C4 is discharged. In this case, through diode VD5 and resistor R11, capacitor C4 will be charged, and the voltage across it will increase. When it reaches the upper switching threshold of the Schmitt trigger, the latter will switch to the opposite state, and a low level voltage will be established at the output of element DD1.3. Now capacitor C4 will be discharged through the opened diode VD4 and resistor R10. When the voltage decreases to the lower switching threshold, the Schmitt trigger will again switch to the opposite state, and the pulse formation process will repeat. As a result, the voltage shape on capacitor C4 will be close to triangular. The effect of this voltage on the non-inverting input of the comparator leads to the formation of current pulses of varying duty cycle at the output of the comparator; these current pulses, flowing through the circuit of the control electrode of the triac VS 1, change the brightness of the garland lamps (they are connected to the “Load” sockets) from minimum to maximum and vice versa.

Zener diode VD3 is necessary in order to “raise” the sawtooth voltage to a level corresponding to the lower switching threshold of the Schmitt trigger. As a DA2 microcircuit, you can use, in addition to the one indicated in the diagram, comparators of the K521SAZ type. When using other types of comparators, you will have to use an output stage current amplifier. Transistors VT1, VT2 can be of any n-p-n structure. Replacing the remaining radio components, it seems, will not cause any difficulties.

Setting up the device consists of regulating the ignition and extinguishing speeds of the garland lamps using trimming resistors R10 and R11.

Advantages of the scheme: More modes than the first scheme, but less than our scheme; there are modes when all the lights are on or all are off, i.e. in this case there is no running fire.

Disadvantages of the circuit: The control circuit for the output thyristors does not provide for gating control pulses with the network zero voltage signal, i.e. the switch creates interference for electrical equipment, which increases the more powerful the load.

The New Year is coming soon! Christmas tree decorations appear on store shelves next to tangerines, sweets and champagne: multi-colored balls, tinsel, all kinds of flags, beads and, of course, electric garlands.

You probably won’t be able to buy a regular garland of multi-colored light bulbs. But there are simply countless different flashing lights, mostly made in China. Microscopic bulbs can be placed on a piece of cardboard or woven into a carpet of wires that can be used to decorate an entire window at once.

Christmas tree garlands are also distinguished by great variety, especially in appearance and design. The cost of such garlands is low, as is the power of the light bulbs.

Most garlands have a small plastic box with one button, a cord with a power plug and wires going to a garland of multi-colored light bulbs. The design of the garland can be very diverse.

The simplest and cheapest option consists of microscopic light bulbs inserted. On the back of the packaging box there are instructions for replacing the bulbs and safety precautions, although no spare bulbs are included. These are the garlands that are sold in the “Everything for 38” chain of stores, although recently they have sold for forty rubles.

Figure 1. Garland for forty rubles

Garlands of another style have small plastic shades on the light bulbs, for example, in the form of transparent flowers with petals. But the box with the button remains the same, although the price of the garland reaches up to two hundred rubles. Let's try to open the box and see what's inside.

Figure 2. Appearance of a garland controller with three thyristors

At the bottom of the figure two wires are shown; this is how the device is connected to the network. There is also a button here that switches operating modes. In the upper part you can see three thyristors and wires going to the garlands.

In the middle of the board there is a black drop mounted on a small printed circuit board. The board has contact pads with which the controller is soldered into the main board.

How many thyristors are on the board

The control electrodes of thyristors, which turn on strings of light bulbs, are connected to the outputs of the microcontroller. The microcontroller has four outputs, but often, instead of four thyristors, only three are installed on the board, and in some cases only two.

The necessary visual effect is achieved by connecting garlands and placing light bulbs: light bulbs of two or even three colors are sealed in one garland. Just such a board is shown in Figure 2.

If you look at this board from the printed circuit board, you can see that three thyristors are soldered, and under the fourth there are holes with tinned contact pads, as shown in Figure 3. In some cases, the holes are not even drilled, they say, whoever wants to drill it himself .

Figure 3. Garland controller board. Free space for thyristor

Here it is worth noting this feature: if the controller output is not connected anywhere, this does not mean that it is not working. The program in all controllers is apparently the same, all controller outputs are used.

This can be easily verified using a pointer tester. If you measure the constant tension on the free leg, the needle will jump, twitch and deviate along with the blinking of other garlands. It is enough to simply solder the missing thyristor into the board, and, please, we get a full-fledged four-channel garland.

The thyristor can be taken from an old faulty board (it happens that the controller becomes unusable) or you can buy an additional garland for forty rubles and remove the thyristor from there. For a good cause, the costs are extremely small!

Schematic diagram of the garland

It is not difficult to draw a circuit diagram using a printed circuit board. There are two types of schemes, slightly different from each other. The first, most advanced option is shown in Figure 4.

Figure 4. Chinese garland controller. Option 1

The entire circuit is powered via VD1…VD4. The garlands are powered by pulsating voltage and are turned on by the controller through thyristors VS1...VS4. Resistor R1 and microcontroller DD1 form a voltage divider, the output of which is a voltage of 12V.

Capacitor C1 smoothes out the ripples of the rectified voltage. Through resistor R7, the mains voltage is supplied to the input of controller 1 to synchronize the circuit with the 220V mains frequency, which allows for phase control of the thyristors. This synchronization allows for smooth ignition and extinction of the garlands. These are the types of boards that can be found in expensive garlands.

The board shown in Figure 3 is assembled according to a somewhat simplified circuit, which is shown in Figure 5.

Figure 5. Chinese garland controller. Option 2

It immediately catches your eye that there are only three thyristors, and only one diode remains from the rectifier bridge. Resistors also disappeared from the control electrodes of the thyristors. But, in general, the consumer properties remained the same as in the previous circuit, despite the fact that the light bulbs light up only when there is a positive half-cycle of the mains voltage on the upper wire of the circuit. Without a rectifier bridge, half-wave rectification is obtained.

This version of the circuit design is inherent in those garlands that are “all forty”. That, in fact, is all that can be said about the circuit design of Chinese Christmas tree garlands.

How to connect powerful lamps

The power of the garlands is low, the bulbs are simply microscopic, and they are unlikely to fit anywhere else besides a home Christmas tree. But sometimes it is necessary to connect a garland with powerful incandescent lamps, for example, for decorative lighting of building facades. This modification has already been given in the article. The diagram of the modified garland is shown in Figure 8 in the mentioned article.

If you don't want to remake the board

It is much easier to do without reworking the controller board. All you have to do is make four powerful output switches with optocoupler isolations and connect them instead of low-power garlands. The power switch circuit is shown in Figure 6.

Figure 6. Powerful power switch with optocoupler isolation

Actually, the scheme is typical, it works flawlessly, and does not contain any pitfalls. As soon as the LED of the MOC3021 optocoupler lights up, the low-power optocoupler thyristor opens and the control electrode and the anode of the BTA16-600 triac are connected through pins 4, 6 and resistor R1. The triac opens and turns on the load, in this case a garland.

An optocoupler should be used without a built-in CrossZero circuit (line voltage zero crossing detector), for example, MOC3020, MOC3021, MOC3022, MOC3023. If the optocoupler has a CrossZero node, then the circuit WILL NOT WORK! This should not be forgotten.

The BTA16-600 triac has the following parameters: forward current 16A, reverse voltage 600V. At a current of 5A and a voltage of 220V, the load power is already a whole kilowatt. True, you will need to install a triac on the radiator.

The metal substrate is isolated from the crystal, as indicated by the letter A in the triac marking. This makes it possible to install triacs on a radiator without mica spacers and insulators for the screw. By the way, it is these triacs that are used in the power regulators of household vacuum cleaners, while the radiator is blown by the air flow at the outlet of the vacuum cleaner.

If the load power is no more than 400W, then you can do without a radiator. The pinout of the triac is shown in Figure 7.

Figure 7. Pinout of triac BTA16-600

This drawing will come in handy when assembling a power switch circuit. It is best to assemble all four power switches on a common printed circuit board. It is better to assemble resistor R from two 2W resistors, which will avoid their excessive heating. The maximum current of the input LED of the optocoupler is 50mA, so a current of 20...30mA will ensure its long-term trouble-free operation.

Figure 8. Connecting power switches to the controller board

In general, everything is clear and simple. The garlands are unsoldered from the controller, and the input circuits of the power switches are soldered in their place. In this case, no intervention is required in the printed circuit wiring of the controller. The only exception is the soldering of an additional thyristor, provided that it can be found. You will also have to make the power cord and plug somewhat thicker, since the original one has a very small cross-section.

If installed correctly and the parts are in good working order, the circuit does not need to be configured. The design of the device is arbitrary, preferably in a metal case of suitable dimensions, which will act as a radiator for triacs.

To ensure electrical safety, the device should be turned on via a circuit breaker, or at least a fuse.

21.11.10

For the manufacture of programmable garland switch you only need four diodes, four transistors, four microcircuits and four thyristors, as well as a dozen resistors and an electrolytic capacitor. After assembly, we get an automatic switch for four lamp garlands, which performs ten switching programs. The switching sequence option is determined by switch SB1 and multi-position switches SA1. So let's move on to implementing the garland switch.

The master oscillator is assembled using microcircuit elements DD 2.1 - DD 2.3. Moreover, its frequency depends on the total resistance of resistors R1 and R2, as well as the capacitance of capacitor C1. Thus, the pulse repetition rate can be changed using resistor R2 “Frequency” and, therefore, the frequency at which the garlands will switch can be changed. The shift register is made on elements DD 3.1 - DD 4.2. The synchronizing inputs of these triggers receive pulses from the output of the generator (pin 8 of the DD 2 chip. At the outputs of the triggers, direct and inverse, logical signals (0 or 1) will be received depending on the position of the SA1 “Program Selection” switch.

To launch the shift register and, as a result, correct the program set by switch SA1, use the “Mode” push-button switch - SB1. With the same position of the SA1 switch, only depending on the duration of holding the SB1 button in the pressed position, you can get several types of combinations for turning on the garlands.

Direct control of the garlands is carried out by thyristors. A constant voltage of 5 V is supplied to the control electrode of the thyristor via a current-limiting resistor. A switch made of a transistor is connected in parallel to the control electrode and the cathode. At logical 0, which comes from the inverse output of the trigger to the base of the key transistor, it is in the closed state. In this case, the thyristor is open, and therefore voltage is supplied to the garland. At logical 1 at the base of the transistor, it opens and the control electrode of the trinistor is shunted. In this case, the thyristor goes into the closed state and the garland turns off.

As mentioned above, by changing the duration of pressing the SB1 button, you can get a wide variety of garland switching combinations, such as running lights, running shadow, etc. Thus, with different positions of switch SA1, the following combinations can be obtained:

"-" means that the garlands are lit at the same time.

The garlands are powered from a 220V network through a full-wave rectifier assembled using diodes VD1-VD4. To power the garland switch circuit, a stabilized power supply with an output voltage of 5V is required. Current consumption is about 200mA. If you use the diodes and SCRs indicated in the diagram, you can connect garlands with a power of up to 500W. Diodes are selected based on a reverse voltage of at least 300V and a forward current that obviously exceeds the total current of the garlands; transistors of the KT315 series with any letter; SCRs of the KU201 or KU202 series with letters from K to N. Capacitor K50-6 series; fixed resistors of the MLT-0.125 series; variable resistor - SP-1; switch SA1 is a biscuit type, having at least 7 positions, for example 11П1Н (the number of positions of this switch is limited by rearranging the latch); button SB1 type MT1-1.

Layout of the garland switch circuit board:

Printed circuit board of the garland switch, view from the terminals side:

The board is made of one-sided foil fiberglass. You can download the programmable garland switch board in .lay format at the end of the article.

Frame garland switch It is better to make it from plastic or use a ready-made standard case. In the same case it is necessary to install U-shaped radiators, which you can make yourself by bending from strips of 2 mm aluminum sheet measuring 30 by 60 mm, or purchase ready-made ones. Install diodes and thyristors on the radiators. The housing must have openings for ventilation. A stabilized power supply can also be mounted in this same case.

A button, a switch and a variable resistor, and if the power supply is also located in the casing of the garland switch, and the power supply switch are installed on the front panel of the casing. Connectors for connecting garlands are installed on the rear wall. You can simplify the circuit a little by refusing to use the K155LE1 microcircuit. In this case, program No. 6 will not be available. Or, as an option, instead of the K155LE1 microcircuit, you can use the K155LAZ microcircuit.

Substitution scheme:

You can simplify this unit somewhat if you use one of the elements of the K155LP5 microcircuit in it. With this option 3, the pin of the microcircuit is connected to the “6” pin of switch SA1. Pins 1 and 2 are connected to pins 12 and 9 of element DD3.1. Don't forget to supply power to the microcircuit - pins 7 and 14. If you accept one of these options, you will need to wire a new printed circuit board.

Garland switch does not require additional configuration. It is possible that in order to switch garlands more clearly, you will need to reduce the resistance of resistors R7 - R10 to 200 Ohms. To change the frequency of the master oscillator, on which the switching frequency of the garlands directly depends, you can select other values ​​of capacitor C1 and resistors R1 and R2.

General conclusions: The circuit is quite simple and executed one to one, does not require additional adjustment, and at the same time it performs quite a lot of lighting effects. The modes of running lights and running shadows are especially interesting. To obtain these effects, twist 4 garlands with an offset of 1 light bulb, i.e. the first lamp is from the first garland, the second from the second, the third from the third, the fourth from the fourth and then again starting from the first.

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