Dimmers: what is it, device, principle of operation in LED lamps, a lamp, a radio tape recorder

Дimmer – a device for controlling power and changing the brightness of light from incandescent / LED lamps. The term comes from the English “dim”, which in translation into Russian means “darken”.

In fact, this is a simplified version of an autotransformer (rheostat) with smaller dimensions and weight.

Below we consider what are the features of the device, in what areas it is used, what are electronic dimmers.

We will separately analyze the device and the principle of operation, talk about the types, pros and cons, as well as the features of operation.

Let’s highlight a few examples and give detailed recommendations for choosing.

Rheostat as a simple dimmer

In simple words, a dimmer is an AC rheostat, but with a more complex design. For the first time, a variable resistor was invented by J. Poggendorf in the XNUMXth century to change voltage (U, V) and current (I, A) by increasing / decreasing resistance (R, Ohm).

Depending on the type of rheostat, the value of R changes smoothly or stepwise.

To reduce the brightness of the light source, you need to reduce the voltage using a rheostat, and for this, resistance is added.

Due to the increase in R and I, the device becomes very hot and gives off heat to the surrounding air. As a result, such a regulator has a low efficiency and, as a result, is not used.

Application

Due to the simplicity of design and functionality, modern dimmers are widely used.

Main areas:

1. Creation of different lighting modes in one and / or several rooms.
2. Reducing electricity costs by switching lighting to standby mode.
3. In a power tool to reduce and increase the speed of the collector motor.
4. Zoning a room into several conditional areas.
5. Illumination of art objects, for example, sculptures or paintings. Different degrees of lighting allow you to draw more attention to the exhibit.
6. Creating the illusion of a person being in an apartment / house, due to a change in the level of lighting.
7. In electric heaters to control their power.
8. Brightness change for birds / animals that have special requirements for this parameter.
9. Heating chicks immediately after birth. Depending on the degree of brightness, the degree of heating also changes.
10. Holding home holidays, when brighter lighting is required at the table, and subdued light in the dance area.
11. Create an intimate atmosphere in the bedroom.

The scope of dimmers is huge, and everyone can come up with a new option, taking into account the capabilities of the electronic device.

The dimmer is equipped with a microcontroller and has a wide range of options:

• changing the brightness level;
• automatic shutdown;
• creating the effect of the presence of people, thanks to automatic on / off;
• flashing / dimming modes;
• smooth on / off lighting;
• remote control via IR channel, radio channel, acoustic noise (for example, cotton), etc.

Electronic dimmers

For those who want to delve deeper into the topic.

These are small and economical devices based on a control key: transistor or triac.

Most of these dimmers have a non-sinusoidal signal at the output, and the sinusoid sections are “cut off” by the available key.

Such dimmers are not designed to connect devices powered by low harmonic currents.

The category of such devices includes electric motors, induction-type transformers for halogens, etc. This is due to the risk of damage to the device due to overheating.

In addition, budget electronic dimmers without special filters are sources of strong interference.

The device and the principle of operation

Outwardly, dimmers resemble ordinary switches, but they allow you to adjust the brightness level. Consider different execution schemes and their features.

On a thyristor

In most cases, a thyristor is used as the main element.

The general algorithm of work is as follows:

1. While the SCR is closed, the capacitor (C) gains charge through the resistance.
2. The voltage of the input half-wave rises.
3. At a certain moment (when the voltage increases more than 32 Volts), the ZD dinistor opens, and after it the SCR thyristor.
4. A current flows between the terminals until the value drops to the level necessary to close the ZD.
5. The capacitor is discharged through D1 (diode) and SCR.
6. The thyristor closes, and the process repeats again.

Due to the opening of the thyristor at certain intervals when passing through “0”, it is possible to “cut off” the sinusoid and thereby change the voltage parameter and the load current.

with choke

Many dimmers use switches that, when added to the circuit, produce electromagnetic (EM) oscillations over a wide frequency range.

Such waves cause current to appear in the wires that combine the dimmer, power supply and load, thereby creating interference.

To combat the problem, inductors or LC filters are used. They are installed near the load or supply source.

The higher the frequency, the more compact the inductor. With the right choice of filter, interference can be kept to a minimum.

On resistors

Dimmers on resistance R are used to change the brightness of incandescent lamps.

Structurally, the device consists of a rheostat / variable resistance, and operates on the basis of Ohm’s law.

As the resistance increases, the current in the bulb decreases, which reduces the activity of the filament.

The design is very simple, but it has a big minus – constant power consumption, regardless of the adjustment position.

Thus, as the resistance increases, the current decreases, but the total load remains unchanged. Excess energy is converted into heat and goes into the air.

Therefore, saving electricity with the help of such devices will not work.

Resistor dimmers are rare, but are used to change the brightness of semiconductor lamps.

This is an analog control method, which is almost never used due to low efficiency and high sensitivity.

On triac

This circuit is a little more complicated than the resistor version. A triac is used here, which plays the role of a key and changes the current parameters.

During operation, the voltage is pieces of negative / positive half-waves, and when the brightness decreases, the light bulb feeds on “stumps”.

A 200 hertz signal comes to the PWM generator. In this case, the brightness changes taking into account the time interval and pulse length. The current / frequency parameters remain unchanged.

Despite the great complexity of execution, the triac circuit has a number of advantages.

So, with increasing brightness, the current load does not increase. In addition, in such devices it is possible to organize control / switching on remotely or near the light source itself.

Types of devices

Depending on the scope and tasks assigned to the dimmer, it may differ in appearance, cost and functionality.

Below we consider the main types of dimmers, which differ in installation, control and type of lamps.

By installation method

According to the installation features, all dimmers can be divided into several types:

1. Wall. It is screwed to the wall in an overhead way or mounted in a mounting box with a diameter of 6,8 cm. With this installation, nothing needs to be disassembled, and the main requirement is the presence of wiring laid along the walls.
2. Portable. Structurally similar to a tee or relay, it has connectors for connection and a plug. The device connects like a normal device with the ability to change the brightness of the lighting. You can connect a lamp, a floor lamp or a lamp to such dimmers. It can be used as a heating source in the presence of an IR lamp.
3. Hidden (modular). This type of installation is relevant for modular structures that are mounted on a DIN rail in a shield with machines. The power first goes to the dimmer, from which the wires diverge to the light sources. The advantage of this design is that it is possible to replace several individual devices with one device with multi-channel control. To adjust the light, you need to open the shield and make settings.
4. built-in. Combines the advantages of hidden and wall dimmers discussed above. Such equipment is mounted in partitions, and a control panel is mounted at the top. Externally, the device has much in common with the switch. The difference is that elements of smooth regulation are provided here.
5. Suspension. Differs in the small sizes, is mounted in a cut of a supply wire of a bulb. The use of such a dimmer allows you to adjust the light even in the absence of an option.

Management

All dimmers differ in the way they are controlled:

1. Swivel. Structurally, they are a casing and a wheel, during the movement of which the brightness changes. Changing the position of the regulator allows you to make the lighting to the maximum or turn off the light altogether. This version of the dimmer has no memory, so after turning it off, all settings are reset and you have to set them from scratch.
2. Push-button. They have much in common with conventional switches. They consist of a pair of buttons responsible for turning on and brightness of the lighting. To select a parameter, you must press, hold down, or release the control element.
3. Swivel-push. Structurally, they have much in common with a switch, in the center of which a round control element is installed. To adjust the brightness, you need to press on it, and to turn it off, press the button. After turning off, the device retains the settings you have made, which makes it easier to use.
   

4. Touch. By principle, they have much in common with the push-button version. The difference is that to change the brightness, it is enough to touch a certain button (up / down arrow), hold it or release it. A separate button or a combination of them is used to enable / disable. There is a function to save modes.

By type of signal transmission

Most modern dimmers provide the ability to remote control.

The following options are possible here:

1. Infrared. In such devices, an IR sensor is provided, directed towards the receiving device. Dimmers with such control have a small price and work only in the direct line of sight of the signal. Even with a thin barrier, control becomes impossible.
2. Radio signal. Unlike the option discussed above, the waves easily bypass obstacles, which allows you to adjust the light even from another room.
3. WiFi. A phone or a tablet PC with software from the dimmer manufacturer installed on it is used as a remote control. To issue a command, you can remotely adjust the lighting parameters. The main thing is that both devices are connected to a Wi-Fi network. Regulation is available simultaneously to several people who have a smartphone with the desired program. For example, all family members.
4. Acoustic. Such dimmers are controlled by giving a voice command. In the memory of the dimmer, the controls (clap, words) are stored, to which the dimmer reacts and executes the command. At this stage, such devices are still being improved to increase efficiency.

Type of lamps used

A compatible dimmer model is used for each lamp type. If the manufacturer declares support for several types of light sources, a “smart” controller is mounted inside the equipment, and this affects the cost.

There are two types of devices here:

1. For voltages up to 230 V. They are suitable for simple / halogen lamps. Inside there is a special regulator that allows you to work both with a 220 V tape and with diode lamps.
2. For 12/24 V. For such devices, a step-down transformer is used.

In terms of bulbs supported, incandescent dimmers are generally suitable for halogens and some LED bulbs.

Advantages and disadvantages

When considering dimmers, you need to understand their strengths and weaknesses.

Pros:

1. Automatic on/off.
2. Possibility of remote control by voice, clap, via radio channel or IR channel, as well as via Wi-Fi network.
3. Simulating the presence of a person, which allows you to scare off intruders from the house / apartment when the owner is in another place. To do this, a certain program is set, which at a certain moment turns on / turns on the light in different rooms.
4. Smooth turning on / off of the lamp, which eliminates current surges and reduces the risk of burnout.
5. The ability to radically change the design of the room and create the necessary atmosphere.
6. Increasing the life of light sources
7. Saving electricity by 10-15%.
8. Savings on the purchase of complex fixtures and chandeliers. The brightness is adjusted using a dimmer without the use of a large number of lamps.
9. Ability to connect to the “smart home” system and set modes by time / command.

Cons:

1. Narrow scope and the ability to use the dimmer for those sources that it supports.
2. High degree of risk when working with moving tools / machinery. The appearance of a stroboscopic effect can lead to a distortion of the real picture.
3. Risk of electromagnetic interference, including at radio frequencies.
4. Low efficiency when used with incandescent lamps. It is often easier to use less powerful incandescent lamps, dimmer circuits or dimmers for LED lamps.
5. The relationship between output voltage regulation and load resistance is non-linear.
6. The power of the dimmer should be equal, and preferably 20-50% more than the total load of light sources.
7. The impossibility of using dimmers with fluorescent lamps and light sources with additional devices: driver, transformer, electronic ballast, etc. The exception is models that are specifically designed for use with dimmers. Some companies are already developing such devices.
8. Non-sinusoidal output voltage, which makes it impossible to connect step-down transformers.
9. For normal operation, it may be necessary to update the wiring and carry out cosmetic repairs.
10. Sensitivity to temperature changes. Dimmer is afraid of both heat and cold.

Special features

Installing a dimmer in a house or apartment does not cause problems. Due to its simple design, the dimmer is easily mounted instead of conventional switches and connected in a similar way.

When buying semiconductor devices, pay attention to compatibility. If there is one, the box should have the inscription “dimmable”.

It is also necessary to look at the installation method, because some models have an overhead design or are built into the gap of the supply wires. We talked about this in more detail above.

Features of operation

When buying and using dimmers, it is important to consider a number of features of their application.

Let’s highlight the basic nuances:

1. The use of dimmers near radio receivers and other high sensitivity devices is not recommended. This is due to the appearance of interference during the operation of such devices. For example, when you turn on a soldering iron with a regulator, the oscilloscope will show extraneous signals, and you will not be able to listen to the receiver at long / medium waves.
2. Connecting a dimmer with an incandescent lamp allows you to avoid a current surge and, accordingly, protect it from burning out ahead of schedule. In reality, such protection does not always work, and at the moment the lamps are turned on, they are still on (although the likelihood of such a situation is lower). By the way, the starting voltage at the minimum level of the regulator depends on the type of dimmer.
3. The efficiency of an incandescent bulb decreases markedly with a decrease in the potential difference at the input. Therefore, instead of reducing the brightness, it is better to connect a lamp of less power and without a dimmer.
4. The dimmer may cause interference when recording audio with a pickup or microphone. This feature must be taken into account in special rooms where sound is recorded or radio centers. In such places, incandescent lamps should be connected directly or using special circuits.
5. When adjusting the lamp power with a dimmer, not only the brightness changes, but also the color temperature. In particular, as the brightness decreases, the light becomes redder.
6. A powerful incandescent lamp, when dimmed with a dimmer, can produce high-frequency noise that can be heard in complete silence. This is due to the mechanical vibrations of the filament, which burns with the participation of currents with high-frequency harmonics (they appear at the moment the triac is switched). If you power the light bulb directly, there will be no such effect.

An example of popular models and their characteristics

The modern market pleases buyers with a huge number of dimmers that differ in design features, mounting method, manufacturer and other parameters.

Below are some of the most popular options.

Dimmer touch RF6-18, 12/24 V, 3*6А/18A, 216/432 W, IP20

Touch control dimmer for lighting 12 and 24 volt LED lamps. Management is carried out using the remote control.

The dimmer capabilities allow you to turn the tape on/off and change the brightness.

Features:

• voltage – DC;
• power – 432 W;
• degree of protection – IP20;
• output voltage – up to 18 V;
• dimensions – 17,8×6,5×5 cm;
• body material – plastic;
• number of colors – 3;
• the possibility of using it with a “smart home” – yes.

Dimmer EKF Minsk ERD06-101-10

Framed dimmer for vertical/horizontal concealed installation.

Works with incandescent lamps and halogen lamps for voltage up to 230 V. Mounted in a spacer or with screws. Supplied with a frame.

The inclusion is carried out by turning or by turning with pressure.

Features:

• voltage – AC;
• voltage – 230 V;
• degree of protection – IP20;
• power – from 40 to 600 W;
• rated current – 3 A;
• dimensions – 8,4×8,4×4,7 cm;
• White color;
• body material – plastic.

Dimmer-mini WI-FI 12-24 V, 8A, 96/192 W, IP20

A small dimmer designed to control a 12 or 24-volt LED strip from Android or iOS phones. Works on the radio channel.

With it, you can turn on / off the device, change the brightness. The dimmer is programmable.

Features:

• voltage – DC;
• power – 192 W;
• degree of protection – IP20;
• output voltage – up to 8 V;
• dimensions – 17,8×6,5×5 cm;
• body material – plastic;
• number of color channels – 3;
• the possibility of using it with a “smart home” – yes.

Recommendations for selection

When buying dimmers for LED lamps, including those working in a radio / lamp, you need to choose wisely. When looking for a suitable option, pay attention to the following points.

Lamp type

Dimmers are able to work with certain types of light bulbs, because universal devices do not exist.

Dimmers can support incandescent lamps, halogens, LED devices, LED modules and other light sources.

Consider the subtleties of choice for different types of lamps:

1. Incandescent. Finding a dimmer for such lamps is the least of all problems. Dimmers for incandescent lamps have a simpler design and are easy to connect.
2. Luminescent. There are almost no dimmers for such bulbs due to the complexity of implementing the circuit. Here you have to use a controller and a ballast circuit, and this requires additional costs.
3. Energy saving. In the presence of ballasts (ballasts), the brightness is changed using a special regulator. If it is not there, dimming is difficult.
4. Halogen. For such lamps, separate dimmers or devices are sold that can be used simultaneously for incandescent lamps.
5. LED LED lamps. For 220 V bulbs, there are no difficulties with the search. At the same time, pay attention to the label and the presence of an inscription indicating the possibility of using such a device.
6. 12 volt LED bulbs. Dimmers for LED lamps of this type require the use of a step-down transformer and a special controller. A special control panel may be required.

Power

When choosing a dimmer by power, it is necessary to calculate the total load. If the calculations are done incorrectly, the device may not work or fail prematurely.

To calculate the total power of the light bulbs, add the parameters that are indicated on the package.

When choosing a dimmer, be sure to add 20-50% to the design power. For example, if the received parameter is 200 W, it is better to take a 300 W dimmer.

Execution features

When choosing, pay attention to the type of dimmer, because the possibility of its installation and combination with the design of the room depends on it.

As noted, on the market you can find keyboards, turn-and-push, touch and other models.

Additional tips

When buying a dimmer in a store, be sure to check it for serviceability and the possibility of using it with the specified type of lamp.

Make sure all functions (including light level memory) are working.

Also, when choosing, pay attention to the manufacturer, service life, color and control features.

Check the package for the presence of all elements for installation and instructions in Russian.

Dimmers are popular devices that have long been used to control light in incandescent lamps and are gaining popularity in other areas.

Today, with their help, you can adjust the brightness of the light in the radio, in a lamp or bulbs of various types for 12, 24 or 220 V.