Scheme of a Chinese garland 4 channels. Chinese garland: scheme, repair. Chinese garland repair: scheme

Instruction

Stock up on several garlands equipped with light bulbs with the same parameters. One of them will be a "donor" of lamps for the repair of the rest.

After disconnecting from the network, open the controller. See if any wires are unsoldered from the board. On one of its sides there are two contact points for connecting a power cord, on the other - five pads for connecting color channels. One of these sites is located away from the remaining four - the common wire of the channels is connected to it. Often, on the soldering to these sites of the conductors that have soldered off from them, the repair ends. When you're done with the controller, close it.

Some garlands are equipped with lamps that self-short when burned out. The lamp in which the shorting device has worked has a lower resistance than the good one, which is why the rest of the channel lamps operate in forced mode. Therefore, burned-out lamps in such a garland must be changed to serviceable ones as soon as possible. They can be taken from the "donor" garland. Replace by de-energizing the garland, carefully solder all connections and insulate with several layers of electrical tape.

If there are no shorting devices in the lamps, if one of them burns out, the entire channel goes out. It is clear that calling each of them separately will take a lot of time, so you have to use the iteration method. After turning off the power, cut the channel exactly in the middle. Ring the sections of the channel from the beginning to the middle and from the middle to the end. Now it is clear in which of them the burnt out lamp is located. This section can also be divided in half and ring both halves of it, and so on until the burnt out lamp is found. Replace it by taking a serviceable one also from the "donor" garland. After that, reconnect the wires in all the places where you cut them. Thoroughly solder and insulate the connections.

Light bulbs are a particular danger in a garland. When turned on, they instantly burn out, while between the thread holders, which are not isolated by anything, the full mains voltage begins to act. Such lamps should be replaced immediately with serviceable ones.

Never close a burnt out or bulb instead of replacing it with a new one, otherwise the remaining bulbs in the channel will be given increased voltage and burn out faster.

Repair of the LED garland is distinguished by two features. The first of them is that the new LED must be turned on in the same polarity as the other diodes of the same channel (a rectifier is installed in the controller of any garland). The second feature is the need to include a resistor in series with each of the LEDs. Its value should be the same as that of the resistors on the other diodes of the same garland. It is impossible to mix light bulbs and LEDs in the same garland, since the former usually have a rated current of 50 or 100 mA, and the latter - 20.

After completing the repair, before continuing to use the garland, be sure to carefully inspect it for the presence of uninsulated connections. Isolate them carefully.

Below are schematic diagrams and articles on the subject of "garland" on the site on radio electronics and the radio hobby site.

What is a "garland" and where it is used, schematic diagrams of home-made devices that relate to the term "garland".

The proposed lighting effects machine contains four groups of LEDs, combined into a New Year's garland, which is controlled by a microcontroller. The basis of the lighting effects machine is a microcontroller, which made it possible to make the device as simple as possible. The controls are a variable resistor R2 and a button ... Schematic diagram of a simple self-made LED garland, which is built on a K155LA3 chip and four low-power transistors. The electronic garland contains a minimum number of non-deficient radio elements, has small overall dimensions, is fire and electrical safe. The garland is powered by a DC voltage source... The New Year is approaching again! And along with it, the question: how would it be more interesting to decorate the Christmas tree? Maybe a Christmas tree garland on multi-colored LEDs? Yes, even such that it has several different modes of operation? And make your guests happy. In this circuit, a full-wave bridge rectifier is used to power a string of LEDs. With the 0.47uF capacitor shown in the diagram, the string current is about 12mA. If the capacitance of this capacitor is increased to 1 uF, the current will be... The red LEDs are lit during the positive half cycle of the AC voltage, and the green LEDs are lit during the negative half cycle... This circuit allows you to light two separate strings of 15 lights from one power source. With a positive half-cycle of an alternating voltage with a frequency of 60 Hz, LEDs from 1 to 15 are lit, and with a negative half-cycle, from 16 to 30. Since the reaction time ... This circuit allows you to make a garland whose color changes from red to green and vice versa about once every second, which makes any holiday illumination more attractive. Two neon lamps - NE1 and NE2 - are connected according to the relaxation oscillator circuit, which is switched ... Capacitor C1 with a capacity of 1 uF for a voltage of 400 V with a Mylar or similar film dielectric works in this circuit as an alternating current limiter that has no losses; a garland of LEDs is connected in series with it. Reactance... For the lighting design of a Christmas tree, a room or a shop window, light garlands are often used, designed for a supply voltage of 220 V. The device circuit allows you to automatically control the inclusion of three garlands, which not only attracts... new year holidays. The variant of the RGB garland controller I propose based on the PIC16P628A microcontroller allows you to reproduce 26 colors and decorate not only the spruce, but also the room or the facade of the building. The schematic diagram of the device is shown in the figure ... If the New Year is coming soon, then you need to come up with something interesting for the Christmas tree. Last year, I had a four-digit seven-segment LED indicator hanging on my Christmas tree, the segments were wired so that it turned out "2014", and the shift register controlled it, so the number "2014" ... Illuminated Christmas decorations usually work as part of a garland, but a good addition would be some self-flickering toys. Figure 1 shows a diagram of an interesting device that is mounted in a Christmas tree toy. It creates with the help of six multi-colored LEDs ... Now LEDs are two-color, with two leads, the color of which depends on the direction of the current through the LED, in almost one case there are two LEDs, red and green, connected in anti-parallel. Such LEDs are used in equipment as indicator modes on ... Simple circuits for home-made LED flashers based on transistor multivibrators. Figure 1 shows a multivibrator circuit that switches two LEDs. The LEDs flash alternately, that is, when HL1 is lit, the HL2 LED is not lit, but vice versa. You can mount the circuit in a Christmas tree ... Schematic diagrams of two simple controllers for RGB LED strips, built on CD4060 microcircuits. The New Year holidays are coming very soon, and I want to somehow update the New Year's illumination. Right now, LED RGB garlands are on sale, consisting of red, green and LED LEDs ... A circuit diagram of a simple flasher for switching nine lines with LEDs is built on a K561IE8 counter. Traditionally, the top of the Christmas tree is crowned with a star. In Soviet times, the star was red, now it can be "cosmic" blue or transparent. Usually a star... New Year's holidays are coming soon, and you need to think about decorating the Christmas tree. Traditional light bulbs are in the past, now is the “age of LEDs”. And colored LEDs usually come in four colors, red, yellow, green and blue. If there are Christmas decorations made of matte translucent plastic, and such ... A three-color LED strip can be used as a screen for a color and music installation. The advantage of an RGB LED strip is that it can be placed anywhere, both under a matte screen, and, for example, hung like a garland on a Christmas tree. Scheme of a color and music installation... This device was developed for the New Year holidays, as a Christmas tree decoration, which, together with a printed circuit board, can be placed on a Christmas tree branch. But, the application can be wider, for example, as an indicator or direction indicator. The device is made on a single chip K561IE8. At the output, on one edge of the printed circuit board, there are nine ultra-bright indicator LEDs in a line ... The article presented to the attention of readers describes the refinement of this souvenir, which made it possible to increase the reliability of work and reduce the requirements for frequency-setting elements. Despite the increase in the number of microcircuits, all elements were placed on a board of the same size...

Hello friends! Fairy times are coming: children and adults have holidays, a Christmas tree on the balcony, vodka and sausage in the refrigerator.
And, the tree has already been brought in? Are you dressing up? Clear. And they probably saved on garlands, Schaub was enough for sausage.
Then take your time. Conduct an audit of the products of the Chinese brothers before winding them on a festive tree.

Chinese garlands are good at a low price. This is where the charms end, and the troubles begin: from fading in the midst of fun to electric fireworks with a fire.

Option one, classic

Photos of my countryman Pavel Shepelev.

A garland of colored incandescent bulbs, a control unit in a green box.
Scenario: we turn it on for verification, we get “BDYSCHSHCH!” with fire and stench, as much plastic flowed. The control unit burned out completely, the reasons are not guessed.

Treatment: nafig green box, garlands in parallel. The garlands shine, though they do not blink.

Option two, fashionable

Multi-channel multi-mode garland on LEDs (light-emitting diode). Good for everyone: bright and colorful and not afraid of concussions, BUT! The Chinese again even wised up for economic reasons. In series with each branch of lights there is a 3 kOhm resistor and some kind of inhumanly low power, I believe - less than 0.125W!
There are 10 such resistors in total. and they all heat up fiercely. And the meanness is that it is not noticeable. You won’t even guess about the existence of these resistors until they start to burn - they are so cunningly mounted.

This garland worked 1 NG. Here's what I found on inspection today.

Low-power resistors overheated, burned, even soldered from LEDs and wires. Only the outer plastic clip kept them in place. When disconnected, the solder cooled down and everything could be started from the beginning.
The error did not appear!

The standard resistor is next to the 0.25W resistor.

I decided to put more powerful resistors and observe. The plastic clip was cut with a clerical knife, the resistor was replaced. The procedure is done for all detected resistors.

The New Year holidays are approaching and on this occasion I want to do something bright and festive! Decided, here, to make a New Year's garland. What could be brighter and more festive than a New Year's garland? :). I decided to make a garland not simple, but heaped up! 12 channels plus IR remote control. In order not to make a garland from scratch, it was decided as donors internal organs spare parts to use ready-made Chinese garlands. This makes sense for the following reasons:
- the cost of garlands, let's be honest, the cost is a penny. Try to buy wires, LEDs, spare parts for the same money ... And if you do not take an LED garland as a goal, then light bulb garlands are now sold almost for nothing;
- an important factor - ready-made lines of LEDs soldered to a heap. Soldering yourself, putting in heat shrinks, making mistakes, redoing 12 lines is a rather dreary job;
- still, I don’t know about you, but I have a certain number of non-working garlands lying around (they are often dragged to me to repair - they settle down) you can not spend money on new ones at all, but collect them from what is.

For starters, watch the video:

ATTENTION!
dangerous voltage 220V!

LIFE THREATENING!
THAT'S WHY:

If you realize the danger assembling such a garland and undertake to comply with safety regulations when working with dangerous voltage, read on for how to assemble a super garland.

1 Garland patients.

As victims, 3 new LED garlands were bought - here they are beauties 🙂

The cost is $ 3 per piece (100 LEDs). But if the Chinese do not save, then they will change themselves! In garlands, in fact, it turned out to be 3 channels each. That is, the controller itself is four-channel, but there are three thyristors and three LED lines. In order to disguise such a disgrace, the Chinese interfere with LEDs of two colors in one line. In short, I had to buy another one :(. But this is not the limit of savings, often there are two channels in general! Be careful - open the box and see how much thyristors cost.

Of the original controllers for the improved garland, resistors, rectifier diodes, thyristors, a button, and boxes will be used. You will need to buy a little more than a dozen resistors, a couple of capacitors, an ATtiny2313 microcontroller and other little things.

2 Scheme.

Here is the diagram of the original garland:

It can be seen from the diagram that the dimming of the LED channels is carried out by thyristors PCR406

Datasheet for thyristor PCR406

I see no reason to change them to something else. To form the supply voltage of the original controller, a quenching resistor is used (the quenching resistor together with the internal resistance of the controller form a voltage divider). The decision is contradictory, but in this case it is justified by cheapness (the controller current is insignificant and the power allocated to the resistor is very small). After weighing the pros and cons of such a decision, I decided to do something similar in my scheme. True, the current of the ATtiny2313 (within 8mA) is much higher than the original controller, but still allows the use of quenching resistors.

Diagram of the new garland controller:

6 Assemble the power supply board.

Before assembling the power supply board, certain measurements must be taken to calculate the value of the quenching resistors. To do this, we connect the soldered controller board with a firmware microcontroller to an EXTERNAL source of 5 volts (+5v and -5v pads) and measure the current consumed. It is not necessary to connect the LED lines, they practically do not affect the current consumption. For a typical ATtiny2313 microcontroller without letter indices, the current consumption should be about 7 - 9 mA. For an ATtiny2313 microcontroller with indices (maybe A, P...) the current will be different.

Based on the obtained current consumption (Ipotr), we calculate the resistance of the quenching resistors in the battery (we take the larger one from the standard series):

R = 430 / Icon

For example, my current consumption was 9 mA, which means R \u003d 430 / 0.009 \u003d 47777 Ohms (take 47 kOhm).

The pile of quenching resistors is made in order to distribute the dissipated power and reduce heating. Resistors must be at least 0.5 W (preferably 1 W each).

Rectifier diodes and a quenching resistor migrate from the original circuit, the rest will have to be purchased. We put the finished board in the body of the garland.

We connect the power supply and controller boards (we take the wires and plug from the original garland). Do not forget to fix the wires soldered to the boards with hot glue, since the wires used by the Chinese, to put it mildly, are shit and can fall off at any moment.

7 Formation of LED lines.

Here's what you have to tinker with, so it's with the formation of 12 channels of LED lines. It will be necessary to assemble a common bundle with twelve lines (plus a common wire) from three bundles (and in the case of three channels in a garland - four bundles) of the original garlands. The garlands need not just be twisted together, but make sure that the LEDs of all twelve channels are arranged in series one after the other. In addition, if the garland is multi-colored, you need to make sure that the colors mix as much as possible.

In general, single-color garlands are better for better visualization of effects, but multi-colored garlands, perhaps, win for creating a brighter image. Here you have to decide either more expressive effects or a more colorful impression.

It takes a long time to explain in words - look at the pictures or think for yourself how you twist the bundles:

The bundles are twisted - now we solder them to the controller in such a way that the channel LEDs follow each other in series.

8 Description of the work of the garland.

When you turn on the garland in the network, it immediately starts working with a random effect. In the process, the effects will randomly change each other. If you press the button, then the effects will sequentially replace each other in turn:
1 Wave
2 shooting star
3 sparks
4 Slow overflows
5 Running lights
6 twinkling lights
7 Everything is on-going out
8 Everything is on fire
0 All off

When selecting an effect with the button, it is delayed for a longer time, but later the effects will again begin to replace each other.

The operation from the remote control is similar to the operation of the button on the controller (we press the button on the remote control - the effects change sequentially). To study the button of any IR remote control, you need to hold down the button on the controller until the garland goes out (about 3 seconds), then you need to press the selected button on the remote control. The button code will be written to non-volatile memory and the garland will return to the effects. Since the code is stored in non-volatile memory, the garland will "remember" the remote control even after disconnecting from the network.

Finally, I think it is not superfluous to recall:

ATTENTION!
The garland circuit is not galvanically isolated from the network dangerous voltage 220V!
Touching any conductive part of the garland included in the network
LIFE THREATENING!
THAT'S WHY:
- if you are poorly versed in electricity - do not repeat this design;
- any actions (soldering, measurements, etc.) with the circuit must be performed only after disconnecting from the network;
- programming of the microcontroller must be done either separately from the board (for example, in a breadboard specially assembled for this), or by powering the garland board from an external voltage source of 5 volts (for example, from batteries);
- the finished structure must be well insulated and inaccessible to small children and animals;
- be careful when assembling the structure!

And here are examples, so to speak, live:

Submit yours and I'll add it here.

Christmas tree from AndreevKV. It turned out big! 🙂

Christmas tree from BOYka59. All my friends and especially the children are delighted with it)

And further!

Happy New Year!

All good mood and happy holidays!

Update 1 (2013)

I didn’t particularly plan to do something with this garland, since there is no time for this this year, but at the request of readers, I still decided on a small update!

Changed a little.
Added 6 new effects:
- a wave running in different directions from 2 LEDs
- sequential filling and descending
— successive filling and decreasing with a variable traveling wave
- random fill and delete
- random filling and removal with a variable traveling wave
- aggressive flicker
The duration of the effect when forced switching (remote control or button) is almost doubled.
That's actually all. The scheme and fuses remained the same. You need to re-upload the new firmware.
- 12-channel supergarland (2013 update)
- Supergarland update source

Happy New Year 2014!!! 😉

Super garland options from blog readers

Sergei Cherniy (Black_S)
The garland is implemented on a single board using SMD components

New Year holidays come as always unexpectedly and bring with them a lot of pleasant troubles. It's time to think about gifts, especially for children, for adults, set the table, pick up good music and be sure to put up a Christmas tree to dress up so that guests have fun and feel comfortable. And the first thing to be hung on the Christmas tree is, of course, Christmas tree garlands. All other toys, as a rule, are hung after the garlands. Next, we will talk about the arrangement of a wide variety of very 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 Christmas tree. This decoration was very flammable. But these times have already passed, everyone began to use electric garlands.

These were ordinary small bulbs from a pocket torch or from the illumination of a scale in a radio receiver, connected in series. From such light bulbs, garlands were made by enthusiasts mainly 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 Christmas tree.

Somewhat later, New Year's garlands began to be produced industrially. Small-sized lamp sockets and colored lampshades of various shapes were used in various designs. Sometimes the plafonds were made transparent, and the lamps themselves were painted.

Flashers and blinkers

But calmly looking at the luminous New Year's garland is somehow sad, I want the soul to turn around. Apparently, this is facilitated by some flashing of the garland. In general, a flashing garland attracts with its beauty, and even with the expectation of some kind of miracle or surprise. If there are several garlands, then it is possible to get various lighting effects, for example, a running fire, a running shadow, running twos and threes, as well as many other interesting effects.

Once such designs were developed by radio amateurs, these schemes were published in amateur radio magazines, as a rule, in the November issues. But these magazines, under the conditions of socialist mismanagement, arrived almost a month late, so by the New Year it was possible to make only last year's flashing light.

Microcircuits with a low degree of integration, primarily K155 and K561 and their varieties, were used as the element base. As an example, we can cite a diagram from the Radio magazine No. 11, 2002.

The basis of the circuit is a DD2 counter of the K561IE16 type, which controls four LED garlands through the keys on the DD3 chip and transistors VT4 ... VT7. The most interesting thing is that the UMS8-01 musical synthesizer chip 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 sound signal is also used to clock the counter. One can only guess how the pictures generated by the LEDs will look against the background of this sound. Naturally, the music also sounds through the speaker.

In the magazine "Radio" No. 11 of 1995, a scheme was published under the name "Automatic device for smooth control of a garland" by A. Chumakov. The circuit provides alternately 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 automatic garland smooth control

If you look closely, the circuit is a triac power controller, made on a two-base transistor KT117A. Only the charge rate of the capacitor does not change 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 controller using a two-base transistor KT117.

Rice. 2. Scheme of the phase power regulator

Microcontroller control of the Christmas garland

As designs on microcontrollers appeared in amateur radio creativity, Christmas flashers, or as they are respectfully called “automatic lighting effects”, also began to be developed on microcontrollers. The most exotic design was published in the Radio magazine No. 11, 2012, p. 37 under the title “A cell phone controls the 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 the K155 series microcircuits, powerful KU202 thyristors (there were simply no others), and in general, a Christmas tree itself could be put on such a flasher.

And here it was enough to change the controller on the faulty board, write a program with lighting effects and supplement it with some kind of control panel. This remote control was an old Siemens C60 phone that was lying around idle. The microcontroller AT89C51 was used as a manager. What came out of this is shown in Figure 3.

Rice. 3. Scheme of microcontroller control of 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 of Intel, later manufactured by Atmel. The constructs 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

A little higher than the article by A. Pakhomov in the same magazine “Radio” No. 11, 2012, an article by I. Nechaev “From the details of CFL. LED flasher for a New Year's toy. The circuit is made on a three-color LED and three DB-3 symmetrical dinistors "mined" from boards from faulty energy-saving lamps.

Rice. 4. Scheme of a simple LED Christmas garland

Each channel of the three-color LED is controlled by its own relaxation oscillator, assembled on the DB-3. Consider the operation of the circuit using the example of one channel, for example red.

The capacitor C1 through the resistor R3 is charged from the rectifier R1, VD1 to the breakdown voltage of the dinistor VS1 (32V). As soon as the dinistor opens, the capacitor C1 is discharged through the red element of the three-color LED, the resistor R4, and the dinistor VS1. Then the cycle repeats.

The red, green and blue elements of a three-color LED have their own generators and work independently of each other. At the same time, the frequency of each generator is different from the other, so flashes occur with a different period. The design is placed in a transparent case and can be used, for example, as a Christmas tree top. If you add a white LED HL2 to the circuit, then colored flashes will occur on a white background.

Many more descriptions of the designs of domestic radio amateurs, old or new, good or bad, could be given, but all of them were made almost in single copies. Modern stores are completely littered with electronics made in China. Even New Year's garlands and those Chinese ones, besides, they are now worth nothing.

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 with the name "All for thirty-eight." The real price is somewhere in the "Mega" one and a half - 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, which includes a power cord with a plug, and four garlands come out. When plugged into the socket, the garlands immediately begin to alternately show all the lighting effects. There are 8 of these effects in total, as indicated by the inscriptions under the button. By pressing a button, you can simply immediately switch 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 string 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 a place on the board for the fourth thyristor, and if you solder it, you get one more additional channel. In the controller, this channel, as a rule, is also flashed. It's just that our Chinese friends saved on one thyristor. Those who have ever opened such control units assure that in some boxes only two thyristors are soldered. The economy must be economical! Our, still Soviet slogan.

Despite such a small size, 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 the power 220 * 0.2 = 44 (W).

Figure 6 shows a printed wiring, according to which you can draw a circuit diagram, which was done repeatedly. Here you can see the holes for the fourth thyristor, just the one that was saved.

Fig.6. Saving details on the example of a Chinese garland

The savings also affected the diode bridge: instead of four diodes, only one is used on this board. And everything else corresponds to the scheme shown in Figure 7.

Rice. 7

The mains voltage is rectified by the diode bridge VD1 ... VD4 and is fed through the quenching resistor R1 to the 10th output of the microcontroller. To smooth out the ripple 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 get by 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 with capacitor C1, then the probability of failure of the MK or simply explosions of thyristors will decrease much.

Deserves special attention resistor R7 connected to pin 1 of the microcontroller directly from the mains wire. This is done to synchronize with the network in order to carry out phase power control. This is exactly what works at the time when the garland lamps smoothly light up or go out.

On the right side of the microcontroller there are thyristor control outputs and a control button, which was described above. The thyristors turn on at the moment when a high level appears at the corresponding output of the MK, then the corresponding garland lights up.

Sometimes New Year's Eve garlands of high power are required, from several hundred watts and above. In this case, the considered circuit can be used as "brains", it is enough just to supplement it with powerful triac switches. How to do this is shown in Figure 8.

Rice. 8. The scheme of the New Year's garland of high power

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, but instead of bulbs, 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 just a Chinese riddle: 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.

Such a design can, apparently, be explained by production technology. For example, the first half is assembled on one line, which is with resistors, and on the other line without resistors. Then it remains only to connect the two halves into one whole. But this is just a guess.