One good electronics engineer said that if there is a relay in the circuit, then it needs to be improved. And one cannot but agree with this: the operating life of the relay contacts is only a few hundred, maybe thousands of times, while a transistor operating at a frequency of at least 1 KHz makes 1000 switchings every second.
Field-effect transistor circuit
This scheme was proposed in the magazine “Radio” No. 9, 2006. It is shown in Figure 1.
The operating algorithm of the circuit is the same as the previous two: with each short click of the switch, it connects new group lamps Only in those schemes there is one group, but in this one there are two.
It is easy to see that the basis of the circuit is a two-digit counter, made on the K561TM2 microcircuit, containing 2 D-flip-flops in one housing. These flip-flops contain a regular two-digit binary counter, which can count according to the algorithm 00b, 01b, 10b, 11b, and again in the same order 00b, 01b, 10b, 11b... The letter “b” indicates that the numbers are indicated in binary system Reckoning. The least significant digit in these numbers corresponds to the direct output of the trigger DD2.1, and the most significant one corresponds to the direct output of DD2.2. Each one in these numbers indicates that the corresponding transistor is open and the corresponding group of lamps is connected.
Thus, the following algorithm for turning on the lamps is obtained. Lamp EL1 lights up as soon as switch SA1 closes. When the switch is briefly clicked, the lamps will light up in the following combinations: EL1; (EL1 & EL2); (EL1 & EL3 & EL4); (EL1 & EL2 & EL3 & EL4).
In order to switch according to the specified algorithm, counting pulses should be supplied to input C of the low-order digit of the counter DD2.1 at the moment of each click of the SA1 switch.
Figure 1. Control circuit for a chandelier using field-effect transistors
Counter management
It is carried out in two impulses. The first of them is a counter reset pulse, and the second is a counting pulse that switches the lamps.
Counter reset pulse
When you turn on the device after a long shutdown (at least 15 seconds), it is completely discharged. When switch SA1 is closed, the pulsating voltage from the rectifier bridge VD2 with a frequency of 100 Hz through resistor R1 forms voltage pulses limited by the zener diode VD1 at 12V. With these pulses, the electrolytic capacitor C1 begins to charge through the decoupling diode VD4. At this moment, the differential chain C3, R4 forms an impulse high level at the R inputs of triggers DD2.1, DD2.2, and the counter is reset to state 00. Transistors VT1, VT2 are closed, so when the chandelier is turned on for the first time, lamps EL2...EL4 do not light up. Only the EL lamp remains on, since it is turned on directly by the switch.
Formation of counting pulses
Through diode VD3, pulses generated by zener diode VD1 charge capacitor C2 and maintain it in a charged state. Therefore, the DD1.3 output is maintained at a low logic level.
When switch SA1 is briefly opened, the pulsating voltage from the rectifier stops. Therefore, capacitor C2 has time to discharge, which will take about 30ms, and a high logical level is set at the output of element DD1.3 - a voltage drop is formed from low to high level, or, as it is often called, the rising edge of the pulse. It is this rising edge that sets the DD2.1 trigger to a single state, preparing to turn on the lamp.
If you look closely at the image, you will notice that its clock input C begins with an inclined segment running from left - up - to the right. This segment indicates that the trigger at input C is triggered by the rising edge of the pulse.
Here is the time to remember about the electrolytic capacitor C1. Connected through the decoupling diode VD4, it can only be discharged through microcircuits DD1 and DD2, in other words, keep them in working condition for some time. The question is how long?
It is unnecessary to say what a big role vision plays for us, and at the same time the light with which we see. That is why lighting devices play such a significant role in interior design for us. In some places they are very simple, like wall lamps or ceiling lamps, and in others they are more elegant. And the more complex the lighting device, the more complex circuit connection he will require, which in itself is a completely understandable conclusion. For example, a chandelier, it usually implies the ability to connect two circuits with lamps, thereby changing the illumination in the room from dim, so to speak intimate, to bright light.
Controlling a chandelier via three wires
We are all already accustomed to the fact that a chandelier with two modes is controlled via three wires. In fact, in this case, two parallel circuits are implemented for each group of chandelier lamps. Each of the circuits begins with a switch, thereby switching the desired circuit and turning on the desired lamps. This option can be called generally accepted. It is simple and can be implemented without minimal investment– one additional wire from the switch to the chandelier. This option is described in detail in one of our articles “Connecting a chandelier”.
However, this option also has disadvantages; this is precisely the third wire, which we mentioned as an advantage of minimizing investments in the connection circuit. After all, imagine this option, when the walls are plastered and wallpaper is pasted. Here it is unlikely that it will be possible to route the third wire quickly and without problems. There are two options here. This is to buy a chandelier that will have several lighting modes and be controlled from a remote control. The second option is to implement a circuit that would provide step-by-step switching for each group of lamps, depending on the number of switchings of the control switch. It is these options that we will talk about further...
Controlling a chandelier via two wires (schemes)
In our case, several options for controlling the chandelier via two wires will be given. Each option will have its own pros and cons, which we will discuss in the process of describing each of the possible connection cases. And now, in order...
1 Option to control the chandelier via two wires
The first option is the simplest, but also the most flawed. It will not require high qualifications from the person who will implement it, nor the use of many radio components. But its disadvantage is that the level of performance characteristics will also not be high. The thing is that the circuit uses a feature of our power supply network, which, as we know, produces AC, with a frequency of 50 Hz. Also a property of diodes that pass this same current in only one direction. Take a look at the diagram.
When a half-wave passes in one of the directions, the current flows through the diode to the lamp and through the diode behind the switch, but located in the same direction. That is, current can only pass through diodes working in pairs, so to speak. A similar situation occurs when a half-wave passes in the opposite direction. Now the current flows through the diode in front of the switch and through the diode behind the lamp, with the diodes also installed in the same direction. So, as you already understand, the circuit is very simple, it is very easy to install. The downside is that the lamps will shine at the incandescent level, since it will be one half-wave, that is, a voltage of 110 volts. There will also be a flickering effect, because in this case the power frequency will also become half - 25 Hz. It is these low performance characteristics that we mentioned earlier.
Option 2 chandelier control via two wires
This option can be called somewhat innovative. But why!? You will understand this from the description of the operating principle of this circuit. Take a look at her first...
When the circuit is closed, all lamps HL4-6 switched on directly and HL1-3 lamps switched on through relay contacts are turned on. But here the relay itself is immediately activated, thereby turning off the HL1-3 lamps. Next, a thermistor comes into operation, which, when current flows through it, begins to change its resistance, it decreases. As a result, the resistance changes to the point that the next time the switch is triggered, the current passes primarily through it, and not through the relay winding. In this case, the relay does not operate and all 6 lamps light up. Here it is important to use resistor R1 to find such a voltage that when the thermistor is cold, the voltage is enough to trigger the relay, and when it is heated, it is enough to hold, but not enough to trigger...
Used radio components: Relay K1 - small-sized with a winding resistance of about 300 Ohms, an operating voltage of 7 V and a release voltage of 3 V. Resistor R2 - three ST3-17 thermistors connected in parallel with a resistance of about 330. Resistor R1 type MLT-0.25 with a resistance of several tens of Ohms . We'll have to pick it up. Diode bridge type KTs407A. Capacitor C1 - 50uF x 16V.
If we talk about the disadvantages of this circuit, then this is, firstly, the need to adjust it to the parameters of the relay and thermistor. The second thing is that you will not be able to switch the light back to a smaller one until the thermistor cools down. The third scheme is devoid of these disadvantages, and is no more complicated...
3 Option to control the chandelier via two wires
The third option is borrowed from Radio magazine, dating back to 1984. But this scheme is still relevant! Let's take a look at it...
Everything here is very simple and logical. Initially, we turn on lamp H1 and at the same time relay K1 is activated, which, through its contacts and diode, begins to charge the capacitor. During a short-term shutdown, the contacts of relay K1 open, thereby the capacitor begins to power the winding of relay K2. While the relay has worked, it is a few fractions of a second or seconds. It all depends on the consumption of the relay and the capacitance of the capacitor. You must turn the switch back on. In this case, the relay will pick up itself and eventually all the lamps will light up. The disadvantage of the circuit is that it is necessary to turn on the switch in time, when relay K2 is still powering the capacitor. Only in this case will it be possible to ensure that all lamps are turned on.
4 Option to control the chandelier via two wires
This option, in addition to the fact that it does not provide any settings, also does not have any restrictions on the time algorithm for turning on the lamps. Like circuit 2, where there is a dependence on the temperature of the resistor, and circuit 3, where you need to have time to turn on the switch a second time before relay K2 has turned off. Let's look at the diagram...
Here, to operate the relay, the same principle is applied that we considered for circuit 1. Only in this case, the relay is activated, and not the lamps. As a result, the relay is able to switch the “full” current and voltage to light the lamps. In addition, if the relays have dual switched contacts, then a third channel can be implemented to connect a third group of lamps. Through contacts K1.2 and K2.2. The scheme has virtually no disadvantages. Unless you need a couple of 110 volt relays. Capacitors are installed to reduce the influence of induction current on the relay windings and to stabilize the current from surges AC voltage networks.
Summarizing the implementation of the ability to control a chandelier via two wires
So, summarizing all of the above, we can focus on two options. This is option 1, when the connection is as simple as possible. It’s worth trying with LED lamps, which have built-in capacitors, which will somewhat soften the blinking.
The second option, if you feel confident that you can implement a simple radio-electric circuit, is to use 4 cases. The option is free of any disadvantages and does not require adjustment or specific algorithms for turning on chandelier lamps.
21-11-2013
Julia Truchsess
Electronic Design
The circuit solves the problem of information exchange via a cable in which there are no free wires left. An amplitude-shift keyed carrier signal can be transmitted over low-voltage power lines.
Sometimes there is a need to organize data exchange when there are no more unused conductors left in the device cable for a dedicated communication line. Typically, this problem is solved using a high-frequency carrier, modulated by data and transmitted along power lines, in particular, through home electrical wires.
Searches on the Internet showed that, despite the relevance of this problem for many developers, no one offers simple, cheap and reliable solutions for low-voltage systems. Below is the result of an attempt to fill this gap. Please note that without special circuit safety precautions, this circuit is not suitable for high voltage applications.
The device, which requires only a handful of discrete components and a couple of chips, can reliably transmit and receive data at speeds of up to 32 kbps on a carrier frequency of 2.6 MHz. This speed could likely be increased many times over by using a higher carrier frequency and changing component ratings accordingly. The circuit can operate on a cable with a capacitance of up to 10 nF and has a low level of electromagnetic radiation. It transmits data in a standard serial asynchronous format compatible with UART, but nothing prevents developers from using Manchester encoding or other protocols.
For simplicity, carrier amplitude manipulation is used and no circuit solutions are provided to suppress intrinsic noise, other than a good signal-to-noise ratio. If desired, developers can implement software error detection and correction.
A PIC microcontroller with a set of peripherals is ideal for our circuit. In particular, its PWM module or programmable timer will be used to generate rectangular pulses carrier signal, as well as a high-speed comparator with rail-to-rail inputs (Figure 1). Of course, if you have the appropriate peripheral devices, you can use any other microcontroller.
The diagram shows two transceivers. Transceiver 1 (left) is the "remote" node receiving power from the "base" Transceiver 2 (right). Inductors L1 and L2 isolate the high-frequency carrier from the low-impedance power rail.
Several nodes can be connected into a multipoint bus if each node is separated from the power line by decoupling inductance. Small surface-mount inductors can be used, but their operating current must provide power to the load with some margin.
The transmitting part of the transceiver is made on a single-channel three-stable U2 bus driver of the TinyLogic () family. The driver outputs are connected to the bus through elements R1 and C1. Resistor R1 provides some filtering to reduce the level electromagnetic radiation, created by steep fronts of a rectangular carrier.
The receiver connection point is formed by elements C2, D2 and D3, followed by two peak detectors. The first detector, with a time constant equal to approximately one-third the duration of the information bit, demodulates the carrier to restore data synchronization. The second, with a time constant approximately 50 times the duration of the data bit, adaptively restores the carrier level. Resistors R3 and R5 divide this level to approximately two-thirds the carrier amplitude.
The outputs of both detectors are connected to the inputs of the internal analog comparator of the microcontroller, which finally generates rectangular data signals, which are then sent to the UART through an external circuit. Resistor R4 slightly biases the non-inverting input of the comparator upward to provide a predictable log level in the absence of exchange. 1".
It should be noted that the input and output of the transceiver are always connected together, so care must be taken that the program ignores signals received from its own transmitter.
In Figure 2, the yellow waveform shows the raw digital data sent by the remote transceiver to the transmit UART port. Blue shows the result of carrier modulation as seen on the power rail. Pink color indicates the demodulated and reconstructed signal coming from the comparator output to the RXD UART input.
Figure 3 illustrates the details of the demodulation and data recovery process. The input amplitude-keyed signal (blue), after processing by two detectors, is fed to the inverting and non-inverting inputs of the comparator (yellow and green, respectively). The data recovered from the comparator output is shown in pink.
Julia Truchsess has had a successful career creating a number of electronic toys, including MicroJammers, Rhythm Rods and Singing Bouncy Baby, many of which have sold millions of copies. In the late 1990s, Julia came up with an idea digital photo frames, the production of which was soon organized under the Digi-Frame brand. After the debut of Digi-Frame, many began to produce similar products large companies, but according to reviewers, the Digi-Frame was "the Rolls-Royce of frames."
Julia runs Pragmatic Designs (www.pragmaticdesigns.com), founded in 1986.
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Buying a new chandelier risks attracting so many associated problems that it’s easier to continue living under a pristine bare light bulb in the ceiling. And this is not a color harmony with curtains, but a full-fledged electric epic.
Do you disagree with the statement? And we don't think so either. Therefore, today we will learn how to attach an infinite number of chandelier wires to two standard wires.
The relay method has a significant drawback: the system wears out quickly. A maximum of several thousand times of use will lead to circuit failure. As you know, it is located in a decorative cap under the ceiling. It is unlikely that anyone will be inspired by the annual procedures of dismantling a chandelier “at the root.”
Let's get acquainted with the relay connection system. Its main elements:
- thermistor R1, R2;
- capacitor C1;
- relay K1;
- diode assembly.
When the lamp is turned on, the cold thermistor (R2) has a high resistance force. The relay receives high voltage, the contacts open and the first 3 lamps in the circuit light up. After 1-2 seconds, the thermistor heats up, which gives a constant but reduced resistance in the circuit.
One of the most popular modern lighting ceiling designs is. To properly connect such a device, you must read the instructions in detail and adhere to certain installation rules.
How to connect wires to a double switch when installing a chandelier with three cables can be read in.
Turning off the power for half a second will be enough to prevent the thermistor from cooling down and all contacts remaining closed. Now all 6 lamps are lit.
You can return the lighting to its previous 50/50 position by turning off the voltage for a few seconds.
The system is somewhat undeveloped, but still has the right to life.
Ways to use semiconductors in chandelier lighting control
The use of transistors is becoming much more popular. Their performance is characterized by long-term operation and high switching frequency. Several controls are provided for review and selection.
Meter based control
Counting pulses are the basis for lighting control. The first one is usually responsible for resetting the counter. Repeated – for serial connection lamps 
Each new press of the switch activates a new pair or group of lamps. To reset the pulses from the counter, it is enough to pause for a third of a minute.
Shift register in control system
The principle is already contained in the name itself. The impulse, hitting the starting point C, is transmitted further along the chain to D and 1. 
The incandescent lamp circuit is connected and operates on the same principle as in the example with a meter.
To search for breaks in a faulty electrical network, special ones are used. How alternative method- this can be done using a radio or smartphone.
Thyristor control system
Rectifier VD6-VD9 powers the entire control circuit. When the switch is turned to the “On” position, the first lamp in the EL3 circuit lights up. 
Next, the capacitors charge and accumulate the high and low signal so that DD1 keeps the transistor and thyristor off. When the switch is turned to the "Off" position, the capacitor is recharged.
Microcontrolling a chandelier
The microprocessor is equipped software. Thanks to this, the operating principle can be unique. After all, such a scheme may have additional embedded functionality in addition to normal lighting. Nevertheless, the same scheme as in previous cases is taken as a basis. 
The connection and control diagrams for the chandelier do not have such significant differences.
Even electronic system remains true to the original principle.
But what really doesn’t add up is the quality and durability.
How a chandelier connected using a two-wire circuit works in the video
If there are several lighting lamps in a network lamp, such as a chandelier, it is advisable to turn them on and off individually or in groups. If the power supply of such a lamp is three-wire, organizing independent control of two groups of lamps will not be difficult; it is enough to use a double switch. With two-wire power supply this is impossible. At the same time, the method of controlling two groups of lamps in a lamp via two wires has been known for decades. It is suitable for cases when it is not possible to replace two-wire wiring with three-wire wiring. It uses rectifier diodes, and the circuit is shown in Fig. 1. Such simple circuit allows, depending on the position of the switches, to turn on one, two or three lamps (groups of lamps). However, previously this method was not widely used due to the fact that the main light source was incandescent lamps. When powered by half-wave rectified voltage, their brightness decreases significantly and noticeable pulsations of the light flux appear.
But if you use compact ones in a lamp fluorescent lamps(CFL), which are currently becoming increasingly widespread, these shortcomings will be eliminated. This is due to the fact that the CFL uses the so-called electronic ballast (a more correct name is electronic ballast - electronic ballast) - specialized pulse block power supply, which is powered from a 220 V network through a built-in rectifier with a smoothing capacitor. This allows low-power CFLs to be powered with half-wave voltage, and in most cases the brightness decreases slightly. Therefore, to control a chandelier with CFLs, you can use the circuit shown in Fig. 1. True, it’s rare, but there are low-power CFLs in which manufacturers, in order to save money, use not a full-wave bridge rectifier in the EPRA, but a half-wave rectifier on one diode. This should be taken into account when using CFLs in a luminaire. In addition, in the rectifier of electronic ballasts (especially low-power CFLs), as a rule, smoothing capacitors of small capacity (2.2...3 μF) are used, which can lead to a noticeable increase in pulsations of the light flux with a frequency of 50 Hz. To eliminate this drawback, CFLs should be powered from additional half-wave rectifiers.
The control circuit for two groups of lighting CFLs via two wires is shown in Fig. 2 (the part of the circuit to the left of connectors XT1, XT2 is the same as in Fig. 1). Here, each of the switches SA1, SA2 supplies supply voltage to its “own” group of lamps. Resistors R1, R3 limit the surge of charging current of capacitors C1, C2 when turned on, R2, R4 ensure their discharge after the lamp is turned off. An additional convenience of this solution is the possibility of using CFLs with different light temperatures, which are more convenient to use in a particular case or together.
Most of the elements for assembling the device can be removed from failed CFLs, be sure to check each part before installation for serviceability. Oxide capacitors must have a rated voltage of at least 400 V, and their capacitance must be at least 8.10 µF, and the more lamps in the group, the larger the capacitance should be (you can use several capacitors by connecting them in parallel). Connectors XT1-XT5 - any screw terminal blocks designed for operation in a 220 V network.
Diodes VD1, VD2 are mounted in the switch, the remaining parts are mounted in the lamp. Manufacture printed circuit board no need, all elements can be placed on a plate made of sheet plastic 1.1.5 mm thick, having previously determined its dimensions based on what is in the chandelier free space. The capacitors are attached to it with hot glue, the terminal blocks with screws, and the remaining elements are mounted on their terminals. Appearance One of the board options is shown in Fig. 3.
After installing the mounted board inside the lamp and checking its functionality, it is covered with a plastic cover.
In a chandelier with the described control circuit, you can also use led lamps, but only those that have a built-in switching power supply, and not a rectifier with a ballast capacitor.
It should be remembered that in accordance with GOST R 51317.3.2-2006, methods of half-wave rectification of current consumed from the network can be used “if the controlled active power technical means does not exceed 100 W."
Publication date: 12.08.2013
Readers' opinions
- Vasily / 10/26/2013 - 12:36
Hello! Less than a month had passed, the 12 Ohm MLT-2 resistor burned out - it could not withstand the inrush currents of the 147 μF capacitance, so I installed three parallel-connected MLT-2s of 56 Ohms each. - Vasily / 10/11/2013 - 05:20
Hello! To completely eliminate flicker, even noticeable only with peripheral vision, it was necessary to set the capacitance at the rate of 2 µF/W (so for 3 lamps of 23 W each, 147 µF was required). When installing a capacitance of 100 uF, the Chinese resistor 0.5 W (not to mention the 0.25 W shown in the diagram) burned out immediately when turned on (it worked fine with a capacitance of 22 uF), so I installed 2 W MLT, 36 Ohm for lamp 23 W, and 12 Ohm for 3x23 W. The diodes were installed by FR207. Thanks for the idea! Good luck everyone!
