The New Year holidays are already very close and if you are thinking about how to make a garland of light bulbs or LEDs with your own hands, below we have provided several original master classes with photo and video examples. The advantage of a homemade electric garland is that you can assemble it from available materials and at the same time develop your skills in working with wires, lamps and a soldering iron, and you can also make a unique configuration of light bulbs that you need. Therefore, feel free to try to repeat this homemade product!
Idea No. 1 – Use 220 Volt lamps!
We bring to your attention the first and most interesting master class, which clearly shows how to make an electric garland with 220 V lamps. So, to begin with, we prepare the following tools and materials (everything shown in the photo):
We begin the assembly by cutting the conductor into 9 pieces of 50 centimeters each and the remaining piece, which will have a length of 150 cm. You can choose a different distance between the lamps, or between the plug and the first lamp, or change the number of lamps. This is the main advantage of a homemade garland - the ability to build it specifically for yourself. For example, according to the size of the room or section of the wall that you would like to decorate.
After this, we clean the ends, for which it is best to use a special one. To prevent the fabric braid from fluffing, we recommend that you burn it, and then apply heat shrink to the edge of the insulation for greater reliability and safety.
After this, you need to assemble the electrical plug of a homemade New Year's garland, which will not be difficult even for an inexperienced electrician: you just need to tighten a couple of screws. To connect the plug, take a long piece of wire, in our case it is 150 cm.
Unscrew the sockets and proceed to connecting 10 incandescent light bulbs. Must be used when making 220 Volt electric garlands. In this case, if one bulb burns out, the others will continue to shine. You can also change the number of connected lamps.
When all the cartridges are collected in one chain, all that remains is to screw in the lamps and light the finished electric garland. Like this step by step instructions You can make your own Christmas tree garland at home! As you can see, everything is quite simple and at the same time interesting!
By the way, you can also use a series connection of light bulbs. Only in this case you need to use, the total voltage of which will be 220 V, for example: 20 pieces of 12 Volts or 40 of 6.
It is worth noting that incandescent lamps have extremely low efficiency and convert most of the energy into heat. Therefore, it is more advisable to use small led lamps, they heat up less and consume less electricity, which will make your garland much more economical. Be careful and do not allow exposed wires on your garland, it is under life-threatening mains voltage!
If any of the points were unclear, we recommend watching the video lesson:
Homemade product operating from a 220V network
Idea No. 2 – Modernize an old electric garland
If you just don't like what was on the tree last year, you can decorate an electric garland in an original way using regular paper coffee cups. Making a beautiful New Year's product is quite simple. To begin, prepare glasses, scissors, glue, tape and scrapbooking paper.
After this, cut and unfold one of the cups, which will become a template for cutting out the decorative wrapper. Having cut out the blanks according to the pattern, we glue them onto the glasses using glue or double-sided tape.
After this, we cut out a place in the bottom of the homemade lampshades for the glowing bulbs and insert them there, securing them on the outside with a thin strip of tape.
That's all - the electric garland is ready! In this way you can greatly upgrade an ordinary LED garland to christmas tree and make it more elegant and festive! However, please note that it is not recommended to alter the garland on incandescent lamps in this way due to the strong heat, which can lead to a fire.
Idea No. 3 – LEDs in action!
The third way to assemble an electric garland for the New Year with your own hands is to use 12 Volt LEDs. To begin, prepare the light bulbs, wire, 12v power supply, resistor, soldering iron, knife and sealant.
If you decide to make a 12-volt LED garland, first calculate the LED installation step. It is recommended to place them every 20 cm. Make marks on the wire and strip these places by about 10-15 mm to connect the diodes.
Next, apply rosin to the bare wires and drop solder using a soldering iron. you can according to our corresponding instructions. After this, solder the LEDs to the wires, observing the polarity. Determining it with LEDs is not difficult, everything is indicated in the picture.
Lastly, the resistor and power supply are soldered. is calculated based on the type and power of LEDs; there is a special calculator for this. When connecting the garland to the power supply, the polarity must be observed, otherwise the garland simply will not light up. By the way, you can also do it without much effort, using improvised means. We recommend watching another interesting master class in the video lesson:
New Year's homemade tennis balls
Idea #4 – Let's use an old keyboard!
By analogy with the previous method, you can make a diode garland with your own hands, using an unnecessary keyboard. As you know, some keys are backlit with 5 Volt diodes (for example, Caps Lock). If you have a non-working keyboard, disassemble it and carefully remove the light bulbs, from which you can assemble a simple electric garland. Next, select suitable resistors and a USB cable with which the connection will be made. The diode garland circuit is as follows:
The legs of the diodes () must be soldered to the black and red wires of the electrical cord, in accordance with. When everything is ready, insulate the exposed contacts and proceed to testing the homemade garland. Such a garland can be powered with a voltage from 5 to 12 volts, while selecting the required resistor for each of the LEDs. In our case, the homemade product will be powered from a 220 Volt network via charger, which will give exactly 5 V at the output. Please note that the number of parallel-connected LEDs with resistors can be increased or decreased, as is the case with a garland on incandescent lamps.
In the video you can also see an example of how to make an LED garland at home:
How to assemble a flashing electric garland with musical accompaniment?
Idea No. 5 – How to decorate the street?
If you want to make an outdoor diode garland for the garden, we recommend using this master class. First, prepare all of the following materials:
- multi-colored diodes, 10 mm in diameter;
- lithium 3-volt batteries;
- thin tape;
- magnets, 13 mm in diameter and 30 mm thick;
- epoxy glue.
Next, you need to attach the diode legs to the battery using glue. The anode (long leg) is attached to the positive pole, and the cathode, respectively, to the side with the “-” sign. When the glue has set, additionally wrap the glowing diode with the battery with tape.
Attach a magnet to the positive pole of the lithium battery and also wrap it with tape several times. Do this with 10-20 light bulbs, then secure them in convenient places on the street, for example, on the facade of the house using magnets. Thus, you can assemble an outdoor electric garland from LEDs yourself. However, this design does not have a switch, and over time the battery will run out, which is not very convenient; to prevent this from happening, you can add a miniature switch to the circuit break.
That's all the master classes we wanted to demonstrate. We hope that now you know how to make a garland of light bulbs and diodes with your own hands, because... The photos, videos and diagrams provided were pretty clear!
Here we go New Year 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 back side The packaging box contains instructions for replacing light bulbs and safety precautions, although no spare light bulbs are included. It is these 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 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
Using a printed circuit board it is easy to create schematic diagram. 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 MOC3021 optocoupler LED 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 in this case 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.
At correct installation and working parts, the circuit does not need adjustment. 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 circuit breaker, or at least a fuse.
We are all familiar with Christmas tree garlands consisting of multi-colored light bulbs. However, recently products based on LEDs have become very popular.
How they are designed, what connection diagram they have and what to do if the garland stops glowing will be discussed in detail in this article.
What does a Christmas tree garland consist of?
What is a garland of LEDs, is it worse or better than a regular one?
Externally, this is almost the same product as before - wires, light bulbs (LED), control unit.
The most important element is, of course, the control unit. A small plastic box on which various operating modes of the backlight are indicated. 
They can be changed by simply pressing a button. The unit itself can be quite well protected with IP44 level of moisture and dust protection. 
What's inside? To open it, use the sharp tip of a knife or a thin screwdriver to pry up the latches from below and remove the protective cover. 
By the way, sometimes it is glued, and not just sitting on the latches.
First of all, inside you will see wires soldered to the board. The thicker wire is usually the network wire, supplying 220V voltage. 
Soldered on the board:
- the controller that creates all the lighting effects
- thyristors, each of them goes to a separate channel of the garland
- resistors
- capacitor
- and diode bridges
The number of board elements depends primarily on the number of light channels of the garland. More expensive models may have a fuse. 
LED garland diagram
The AC mains voltage is supplied to the power controller through resistors and a diode bridge, already rectified and smoothed through a capacitor. 
In this case, this voltage is supplied through the button, which is open in the normal state. When you close it, the controller modes switch.
The controller in turn controls the thyristors. Their number depends on the number of backlight channels. And after the thyristors, the output power goes directly to the LEDs in the garland.
The more such outputs, the more varied the colors the product can have. If there are only two of them, this means that only two parts (or halves) of the garland will work in different modes - some bulbs will go out, others will light up, etc. 
In fact, these two lines of diodes will be connected on two channels in series. They will connect to each other at the end point - the last LED. 
If for some reason you are annoyed by the blinking of the garland and you want it to glow evenly with only one color, it is enough to short-circuit the cathode and anode of the thyristor on the back side of the board using soldering. 
The more expensive the garland you have, the more outgoing channels and wiring will leave the control board.
At the same time, if you follow the traces of the board, one of the mains voltage outputs is always supplied directly to the final LED of the garland, bypassing all circuit elements. 
Causes of malfunction
Situations with garland malfunctions are very diverse.
At the same time, remember that the most important element - the microcircuit on the board - “burns” very, very rarely.
In approximately 5-10% of all cases.
- Poor contact on wires
- LED in one of the light bulbs
- Capacitor
- Resistance
- One of the diodes
- One of the thyristors
- Controller chip
Bad soldering
If your backlight suddenly stops working, first of all always check the soldering of the supply and output wires. It is quite possible that the entire contact was held only by hot glue. 
It’s worth moving the wiring and contacts as usual.
The most common problem with Chinese garlands is the use of very thin wires, which simply break off at the solder points on the board.
To prevent this from happening, all contacts after soldering must be covered with a thick layer of hot-melt adhesive. 
And when stripping such veins, it is advised to use not a knife, but a lighter. Instead of whittling away the insulation with a blade, lightly heat and melt it with a lighter. 
After that, simply remove the outer layer with your nails without damaging the veins themselves.
LED damage
If the wire contacts are OK and you are sinning on one of the diodes, how can you check if it is faulty? And most importantly, how to find it among the whole series of light bulbs? 
First of all, unplug the garland from the outlet. Start with the last diode. The power wire comes to it directly from the control unit.
An outgoing conductor is soldered to the same leg. He goes to the next branch of the light channel. You also need to test the diode between its two power wires (input-output). 
You will need a multimeter and its somewhat modernized probes. 
Thin needles are tightly tied to the tips of the tester probes with a thread so that their points protrude a maximum of 5-8mm. 
Wrap everything on top with a thick layer of electrical tape. 
Since the LEDs are soldered, you won’t be able to simply pull them out of the light bulb like in regular garlands.
Therefore, you will have to pierce the insulation of the conductors to get to the copper conductors of the wiring. Switch the multimeter to diode testing mode. 
And you begin to sequentially pierce the supply wires near each suspicious diode. 
If you have a garland not 220V, but 12V or 24V, which is connected from this power supply: 
then the working LED from the multimeter battery should light up. 
If this is a 220V backlight, then check the multimeter readings.
On working elements they will be approximately the same, but the faulty one will show a break.
The method is of course barbaric and damages the insulation, but it works quite well. True, after such punctures, it is better not to use street garlands outdoors.
Chaotic blinking
There is a situation when you turn on a garland and it starts blinking chaotically, sometimes brighter, sometimes dimmer. It sorts through the channels on its own.
In general, one gets the impression that this is not some kind of factory effect, but as if the garland has “gone crazy”.
Most often the problem here is the electrolytic capacitor. It may swell and swell a little, and this will be clearly visible even to the naked eye. 
Everything can be solved by replacing it. The denomination is indicated on the case, so you can easily purchase and select a similar one in radio parts stores. 
If you replaced the capacitor, but it did not give any effect, where to look next? Most likely one of the resistors has burned out (broken). It is quite problematic to visually determine the breakdown. You will need a tester.
You take resistance measurements, having previously learned its nominal (normal) value from the markings. If it doesn't match, change it. 
Part of the garland does not shine
When any of the channels on the garland does not work completely, there may be two reasons.
For example, a breakdown on one of the thyristors or diodes responsible for it.
To make sure of this for sure, simply unsolder the wiring of this channel on the board from its place and connect there the adjacent channel, which is known to be working. 
And if at the same time another channel also stops working, then the problem is not in the garland itself, but in the components of its board - a thyristor or diode. 
You check them with a multimeter, find the ones that match the parameters and change them.
The garland shines dimly
There are also not entirely obvious accidents, when the LEDs of a separate channel seem to be on, but rather dimly compared to the others. 
What does it mean? The controller circuit is working fine. When you press the button, all modes are switched.
Testing the parameters of the diode bridge and resistance with a tester also does not reveal any problems. In this case, the only thing left to blame is the wires. They are already quite frail, and when such a multi-core wire breaks, its cross-section decreases even more.
As a result, the garland is simply not capable of starting the LEDs in the nominal brightness mode, since they simply do not have enough voltage. How to find this torn vein in a long garland? 
To do this, you will have to walk along the entire line with your hands. Turn on the garland and start moving the wires near each LED until all the backlight lights up at full strength.
According to Murphy's Law, this may be the very last piece of garland, so be patient.
As soon as you find this area, pick up a soldering iron and disassemble the wires on the LED. Clean them with a lighter and solder everything again. 
Then insulate the soldering area with heat shrink. 
New Year's holidays come unexpectedly as always and bring with them a lot of pleasant troubles. It's time to think about gifts, first of all for children, for adults, set the table, select good music and be sure to put up a Christmas tree and decorate it so that the guests have fun and comfort. And the first thing to be hung on the tree is, of course, Christmas tree garlands. All other toys, as a rule, are hung after the garlands. Next we will talk about the design of a wide variety of different New Year's garlands - old and modern.
In ancient times, when there was no electricity and the New Year was already celebrated, special New Year's candles were lit on the tree. Such decoration was very fire hazardous. But these times have already passed, everyone began to use electric garlands.
These were ordinary small light bulbs from a flashlight or from the backlight of a dial in a radio, connected in series. Garlands from such light bulbs were made mainly by enthusiasts with their own hands. They just picked up a soldering iron, who, of course, knew how to use it, took the wire and light bulbs, and after a while the New Year's garland was already hanging on the tree.
Somewhat later, New Year's garlands began to be produced industrially. Small-sized lamp sockets and colored lampshades of various designs were used different shapes. Sometimes the lampshades were made transparent, and the lamps themselves were painted.
Flashing lights and blinkers
But it’s somehow sad to calmly look at the glowing New Year’s garland; you want your soul to turn around. Apparently, this is facilitated by some kind of blinking of the garland. In general, a flashing garland attracts with its beauty, and even with the expectation of some miracle or surprise. If there are several garlands, then it is possible to get various lighting effects, for example, running fire, running shadow, running twos and threes, as well as many other interesting effects.
Once upon a time, such designs were developed by radio amateurs; these schemes were published in amateur radio magazines, usually in the November issues. But these magazines, in conditions of socialist mismanagement, arrived almost a whole month late, so for the New Year it was only possible to make last year’s flasher.
Microcircuits were used as the element base small degree integration, primarily K155 and K561 and their varieties. As examples, we can cite a diagram from the magazine “Radio” No. 11, 2002.
The basis of the circuit is a DD2 counter of type K561IE16, which controls four LED garlands through switches on the DD3 chip and transistors VT4...VT7. The most interesting thing is that the UMS8-01 music synthesizer microcircuit is used as a master oscillator. Such microcircuits were once used for voicing children's toys and musical calls: they simply played the melodies recorded in them.
So, in this circuit, the output audio signal is also used to clock the counter. One can only guess what the pictures generated by the LEDs will look like against the background of this sound. Naturally, music also sounds through the speaker.
In the magazine “Radio” No. 11, 1995, a diagram was published called “Automatic smooth control of a garland” by A. Chumakov. The circuit provides alternate smooth ignition and extinguishing of the garland at a speed set by the control unit. The device diagram is shown in Figure 1.
Rice. 1. Scheme of the automatic garland smooth control
If you look closely, the circuit represents a triac power regulator made on a two-base transistor KT117A. Only the charging rate of the capacitor is changed not manually using a variable resistor, but by switching individual resistors using a counter - decoder K561IE8. For comparison, Figure 2 shows a diagram of a phase power regulator using a dual-base transistor KT117.
Rice. 2. Phase power regulator circuit
Microcontroller control of New Year's garland
As designs on microcontrollers appeared in amateur radio creativity, Christmas tree flashers, or as they are respectfully called “light effect machines,” also began to be developed on microcontrollers. The most exotic design was published in the magazine “Radio” No. 11, 2012, page 37 under the title “A cell phone controls a Christmas tree garland”, author A. Pakhomov.
The design was based on a board from a faulty Chinese garland. The author writes that he was attracted by the originality of the output stage, controlled directly from the MK. He recalls those flashers that were built on K155 series microcircuits, powerful KU202 thyristors (there were simply no others), and in general, you could put a Christmas tree on such a flasher.
But here it was enough to change the controller on the faulty board, write a program with lighting effects and add some kind of control panel. This remote control became an old Siemens C60 phone that was lying around idle. The AT89C51 microcontroller was used as a controller. What came out of this is shown in Figure 3.
Rice. 3. Microcontroller circuit for controlling a New Year's garland (click on the picture to enlarge)
Although this controller is already outdated and discontinued, it is one of the best developments from Intel, later produced by Atmel. Designs on this MK never freeze, they do not require a watchdog timer. The command system is so good that it still remains unchanged, despite the appearance of new models of the MSC-51 family.
Simple LED flasher
Just above the article by A. Pakhomov in the same magazine “Radio” No. 11, 2012, an article by I. Nechaev “From CFL parts. LED flasher for a New Year's toy." The circuit is made on a three-color LED and three symmetrical DB-3 dinistors “extracted” from boards from faulty energy-saving lamps.
Rice. 4. Scheme of a simple LED New Year's garland
Each channel of a three-color LED is controlled by its own relaxation oscillator assembled on a DB-3. Let's consider the operation of the circuit using the example of one channel, for example red.
Capacitor C1 through resistor R3 is charged from rectifier R1, VD1 to the breakdown voltage of dinistor VS1 (32V). As soon as the dinistor opens, capacitor C1 is discharged through the red element of the three-color LED, resistor R4, and dinistor VS1. Then the cycle repeats.
The red, green and blue elements of a three-color LED have their own generators and operate independently of each other. At the same time, the frequency of each generator is different from the other, so flashes occur with different periods. The structure is placed in a transparent case and can be used, for example, as a Christmas tree topper. If you add a white HL2 LED to the circuit, then color flashes will occur on a white background.
It would be possible to give many more descriptions of the designs of domestic radio amateurs, old or new, bad or good, but all of them were made in almost single copies. Modern stores are completely littered with electronics made in China. Even New Year’s garlands and those Chinese ones, besides, they don’t cost anything now.
Literally a year or two ago, such New Year's garlands were sold at a price of 100...200 rubles, and on the eve of the current 2014 New Year they are sold in stores called “Everything for thirty-eight.” The real price, somewhere in Mega, is one and a half to two rubles. Let's see what's hidden inside.
Chinese New Year garland controller
Outwardly everything looks very simple. A small plastic box with one button, into which a power cord with a plug goes in, and four garlands come out. When plugged into the socket, the garlands immediately begin to show all the lighting effects one by one. There are 8 of these effects in total, as indicated by the inscriptions under the button. At the touch of a button you can simply switch directly to the desired light pattern.
If you open the box, then everything inside is also quite simple, as shown in Figure 5.
Rice. 5. Chinese LED garland control board
Here you can see all the details. The microcontroller, as always, is made in the form of a drop of black compound, next to it is a control button, an electrolytic capacitor, a single diode and three output thyristors.
There is also room on the board for a fourth thyristor, and if you solder it, you get one more additional channel. In the controller, this channel is usually also stitched. Our Chinese friends just saved on one thyristor. Those who have ever opened such control units claim that in some boxes there are only two thyristors sealed. The economy must be economical! Ours, still a Soviet slogan.
Despite such small sizes, PCR406 thyristors have a reverse voltage of 400V and a forward current of 0.8A. If we assume that the load consumes only 25% of the maximum current, then at a voltage of 220V it is possible to switch a power of 220 * 0.2 = 44 (W).
Figure 6 shows a printed wiring diagram, from which you can draw a circuit diagram, which has been done several times. Here you can look at the holes for the fourth thyristor, the one on which you saved.
Fig.6. Saving parts using the example of a Chinese garland
Savings also apply to the diode bridge: instead of four diodes, only one is used on this board. And everything else corresponds to the diagram shown in Figure 7.
Rice. 7
The mains voltage is rectified by the diode bridge VD1...VD4 and supplied through the quenching resistor R1 to pin 10 of the microcontroller. To smooth out the ripples of the rectified voltage, an electrolytic capacitor C1 is also connected here. The current consumption of the microcontroller is quite insignificant, so in the future, instead of a bridge of four diodes, the Chinese decided to make do with one.
A small note about increasing the reliability of the entire circuit as a whole. If you solder a zener diode with a stabilization voltage of 9...12V in parallel to capacitor C1, then the likelihood of failure of the MK or simply explosions of thyristors will decrease significantly.
Resistor R7, connected to pin 1 of the microcontroller directly from the network cable, deserves special attention. This is done to synchronize with the network in order to carry out phase control of power. This is exactly what works when the garland lamps smoothly light up or go out.
On right side The microcontroller contains thyristor control outputs and a control button, which was described above. The thyristors are turned on at the moment when the corresponding output of the MK appears high level, then the corresponding garland lights up.
Sometimes New Year's Eve requires high-power garlands, from several hundred watts and above. In this case, the considered circuit can be used as a “brain”; it is enough to simply supplement it with powerful triac switches. How to do this is shown in Figure 8.
Rice. 8. Scheme of a high-power New Year's garland
Here you should pay attention to the fact that the MK is powered from a separate source galvanically isolated from the network.
LED garlands
They use the same controller with one button, the same thyristors, only instead of light bulbs, the garlands are made up of LEDs of three or four colors. Each garland contains at least 20 LEDs with current-limiting resistors.
Moreover, the design of such a garland is simply a Chinese mystery: in the first half of the garland a resistor is soldered to each LED, and the remaining ten pieces are simply connected in series. Again, saving ten resistors at once.
This design can apparently be explained by production technology. For example, on one line the first half is assembled, which is with resistors, and on the other line without resistors. Then all that remains is to connect the two halves into one whole. But this is just a guess.
Electric garland controller is an electronic device that creates static-dynamic effects by changing the magnitude and time of supply of the supply voltage.
Electric garland is a decorative multi-colored light decorative decoration that consists of LEDs or incandescent light bulbs connected in series using electrical wires.
Scheme, device and principle of operation
controller for garlands
To successfully repair a controller for garlands and duralight with your own hands, you need to know its electrical circuit, the principle of its operation and the design of the controller.
Electrical circuit and operating principle of the controller
The electrical circuit is very simple and even a person who does not have special knowledge can understand it. The drawing shows a diagram of the dynamic light system. It consists of two parts – a controller and garlands.
The supply voltage from the 220 V AC mains is supplied through the mains plug to a rectifier bridge consisting of four diodes VD1-4. There is no smoothing capacitor, since thyristors require varying voltage to operate.
The rectified voltage of positive polarity (+) from the diode bridge is supplied to the common wire of the garland and through resistor R2 to pin 10 of the DD1 type Q803 microprocessor. To smooth out ripples, an electrolytic capacitor C1 is installed after the resistor.
Capacitor C1, pin 2 of the microprocessor and the cathodes of thyristors VS1-4 are connected to the negative terminal (–) of the diode bridge.
To generate a control voltage for supply to the control electrodes of the thyristors, voltage is supplied directly from one of the network wires to pin 1 of DD1 through resistor R1.
Button SA1 is intended for selecting light-dynamic operating modes of the system. Each short press activates the next lighting effect. Simple controllers are usually programmed with 8 options for lighting the garland.
The control terminals of thyristors VS1-4 are connected to microprocessor outputs 3-6. When the positive voltage level at the output of the microcircuit exceeds 2 V relative to the cathode (k), the thyristor opens and supply voltage is supplied to the garland.
Device and design of the controller
A simple Chinese controller consists of two halves of the housing, between which a printed circuit board made of foil getinax is placed.
The wires supplying the supply voltage and going to the garlands are connected to printed circuit board controller by soldering directly to the contact pads of printed conductors.
Buttons for switching operating modes are pseudo-touch and mechanical. In the photo on the left there is a pseudo-sensory one; a layer of conductive rubber is applied to the end of the button pusher. When you press the button, the conductive rubber closes the unvarnished adjacent conductors of the printed circuit board, and the control signal is sent to the microprocessor.
The controller contains a packageless microprocessor, which is soldered on a separate printed circuit board. Such microcircuits are popularly called “blots”. The printed circuit board containing the microprocessor is inserted into a slot on the controller circuit board and is held in place by soldering the printed circuits.
LED and incandescent garlands are soldered directly to the controller board. For duralight cords, due to its design features, the end of the cable is equipped with a round (for round) or flat (for flat) connector. The number of pins depends on the number of chains of LEDs or light bulbs in the duralight.
Repair of the controller for garlands
Attention, the electrical circuits of the controllers are galvanically connected to the phase of the electrical network and therefore extreme care should be taken. Touching an unprotected part of a person’s body to bare areas of a circuit connected to electrical network may cause serious damage to health.
Before repairing the controller, it is necessary to carry out diagnostics in order to determine which part of the system the malfunction is located in - in the controller or in the garland. Only after this can you choose a repair method.
| Instructions for troubleshooting the controller and garland | |||||
|---|---|---|---|---|---|
| External manifestation | Faulty | Remedy | |||
| Single-channel or multi-channel garland does not shine | There is no voltage in the outlet, power cord, controller or garlands | Carry out diagnostics | |||
| In a multi-channel duralight, only part of the channels light up | Duralight connector, controller or daisy chain | Check the connector, re-solder the wires of the good and bad circuits in the controller. If after re-soldering the chain lights up, then the controller is faulty. Otherwise, one or more LEDs have burned out | |||
| In a multi-channel garland, only part of the threads lights up | Controller or garland strings | Resolder the wires of the good and bad threads in the controller. If after re-soldering the LEDs light up, then the controller is faulty. Otherwise, one or more elements in the chain have burned out | |||
| One or more channels are constantly lit in the garland | Controller | Breakdown of the anode-cathode transition of the thyristor at the constantly glowing channel, the microprocessor is faulty | |||
| When you press the button, the dynamic light mode does not change | Controller | Briefly short-circuit the leads or pads of the button. If the mode has changed, then replace the button or wash the pseudo-sensory contacts on the printed circuit board. If this does not help, replace the microprocessor | |||
Repair example
multi-channel dynamic light controller duralight
I had to repair a burnt-out controller from a flat duralight as a result of a short circuit due to water getting into the junction of the connector and the cord.
The screws of the fastener were rusty from water exposure and there were traces of soot inside it from a short circuit.
The connector coming from the controller for connecting the duralight cord was also covered with soot between the pins. Therefore, before starting to repair the controller, to prevent the short circuit from recurring, it was removed using a rag soaked in alcohol. The soot can simply be scraped off with a knife.
To disassemble the controller housing, you need to insert a knife blade between the halves where the wires exit and turn it to push them apart. They usually separate without much effort.
After disassembling the controller case, it became clear why it did not work. One of the thyristors, due to the current flowing through it exceeding the permissible one, exploded and even covered the surface of the printed circuit board with soot.
On the side of the printed circuit conductors of the board, two tracks melted and burned out. The controller does not provide protection; there is no fuse installed, so when the output is closed, the tracks and thyristor served as it.
To control the supply of supply voltage to the garlands, the controller used PCR606A type thyristors, designed for operating voltage up to 600 V and switching current up to 600 mA. Testing the thyristors with a multimeter showed that all the anode-cathode junctions were broken. We had to replace them all with new thyristors with the same parameters of the MCR100-8 type. PCR406 thyristors, which are often installed in LED and incandescent Christmas tree garland controllers, are also suitable replacements.
This controller was used for switching a flat three-channel duralight 25 meters long and the current consumption by the threads exceeded 0.6 A, therefore, two thyristors were installed in each channel of the controller connected in parallel (the terminals of the same name are connected to each other).
After replacing the thyristors, we also had to replace two 1N5399 type diodes (1000 V, 1.5 A) of the rectifier bridge, which turned out to be broken when tested with a multimeter. The diodes were taken from a faulty computer power supply because the commonly used 1N4007s are rated for a maximum current of 1A.
After replacing the thyristors and diodes, the burnt remains of the tracks were removed and jumpers made of fluoroplastic wire were soldered in their place. Now you can apply supply voltage to the controller and check for functionality.
But the circuit, despite all the working elements, did not work. The microprocessor also had to be replaced.
There was a faulty Christmas tree garland, the controller of which had the same Q803 type processor. After working outdoors, many of the LEDs in this garland failed and we never got around to repairing it.
The microprocessor was removed from the Christmas tree garland controller and installed in the duralight controller being repaired. All that remains is to check the operation of the controller.
Ways to check the operation of the controller
duralight and Christmas tree garlands
If a working garland is at hand, then you need to connect it to the controller and its functionality will be obvious. But in my case, the duralight cord was hanging on the facade of the building and removing it was a difficult task. Therefore, we had to test the controller in laboratory conditions.
The easiest way is to use a multimeter. To do this, you need to set the multimeter switch to the mode for measuring direct voltage of at least 300 V. Next, touch the common, positive wire of the controller with one probe, and the output of any of the channels with the second. If the voltage value changes from zero to the mains voltage, then with a high degree of probability the controller is working.
If you load the channels with a 10-20 kOhm resistor, the test will be more reliable. Instead of a resistor, you can connect a 220 V incandescent light bulb with a power of 15-50 W. Then, without instruments, it will be immediately clear from the glow of its filament how the controller works.
Since I have a two-channel oscilloscope on my desk, I like to check everything with it. The oscillograms show the behavior of the current and the magnitude of the voltage.
The upper oscillogram shows the voltage waveform at the cathode of the thyristor, that is, immediately after the diode bridge. On the bottom - on the anode, the signal that goes to the garland. As you can see, the sine wave is cut in half, which means the brightness of the diodes or light bulbs of the garland string will be half less than the maximum.
After the repair was completed, the controller was connected to the duralight cord and confirmed its functionality.
I was “lucky”; the controller was repaired, in which only two diodes, two resistors and an electrolytic capacitor survived. But usually only thyristors or diodes of the rectifier bridge fail.
The DIY repair took about two hours. In case of such a complex breakdown, when 80% of the parts are burned out, it is more advisable not to tinker, but to buy a new one. But it’s not always possible to choose the right one, and it will take just as much time to purchase, not counting the extra financial costs. Therefore, repairing the controller for duralight and Christmas tree garlands, even the most complex, is economically feasible.
How to connect a garland
duralight bypassing the controller control circuit
If there is no technical capability or time to repair the controller, but the garlands are in good working order, then you can turn them on directly, bypassing the controller’s control circuit. In this case, the duralight or Christmas tree garland will glow constantly, without dynamic light effects.
Connecting a Christmas tree garland
made from incandescent light bulbs directly
If incandescent light bulbs are assembled in series and are designed for a supply voltage of 220 V, then the wires going to the garlands can be soldered directly to the wires coming from the power cord. The polarity of the connection does not matter. You can even remove the controller completely and solder the wires of the garland and the power cord together in pairs.
If you look at the photo below, the yellow wire needs to be soldered to the blue or brown one coming from the power cord, and both brown ones together to the remaining free wire of the power cord.
Connecting a duralight LED cord
or Christmas tree garland directly
Since LED garlands and duralight require voltage to operate DC, then they cannot be connected directly to the network, but only after the rectifier bridge.
The photo shows a printed circuit board for a two-channel duralight cord controller. Although the controller was working properly, to highlight the date of the coming year, the management decided that the garland should glow permanently.
The two right wires, brown and green, come from the power cord. The left wire is yellow, is common to the garlands and is connected to the positive terminal of the diode bridge. To the right of the yellow one, two blue wires go from the garlands to the anodes of the thyristors. Wire colors in controllers from different manufacturers may be different.
I had to turn on two duralights directly; in the second controller, the colors of the wires of the garlands were different. First you need to unsolder the wires from the controller, as shown in the photo.
All that remains is to solder the tinned end of the additional wire to the negative terminal of the diode bridge.
After assembling the controllers, they were placed in a sealed box, in which they were connected to a double socket. The check showed that the backlight works constantly.
The design of the product was five meters long and consisted of numbers nailed onto two wooden blocks, also made of wood. On the front side, the numbers were covered with white plastic. The coming New Year looked good on the façade of the building.
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