Dimmer for Led! How to choose?


Do you know what a dimmer is, do you know where to apply a dimmer, what is the importance of this device within electronics? If your answer is no or if you have any questions on the subject, come and learn a little more, in this article we will cover what is dimmer without mysteries.

What is dimmer?

Dimmers are known as luminosity variators, they were widely applied to incandescent lamps that had filaments (resistors), the first dimmers performed the variation of luminosity through a voltage drop in an internal resistance which consumed the same average power of the lamp, this way there was no saving of electricity when using a dimmer.

With the evolution of electronics, devices capable of performing switching of the alternating voltage were developed, in order to modulate the average voltage in the load, thus in addition to being able to vary the brightness of a lamp, we can also generate energy savings, this is one of the main objectives of a dimmer.

Usually to perform this type of effect we use a component known as TRIAC, or Triode for Alternating Current it is an electronic component equivalent to two (SCR / thyristors), connected in antiparallel and with the trigger terminal (or trigger – gate) connected together. This type of connection results in a bidirectional electronic switch that can conduct electrical current in both directions, therefore, the TRIAC is part of the thyristor family. Observe its electronic symbology and representation:

Electronic symbology for a triac of the thyristor family

A TRIAC can be triggered by an alternating current applied to the trigger terminal (gate) or terminal G as shown in the figure. Once triggered, the device continues to conduct until the electric current is below the cut-off value, as in the final voltage value of half the cycle of an alternating current wave, so the TRIAC can modulate the alternating voltage which makes it an excellent control device for alternating current circuits, this device is capable of driving large electrical powers with a control circuit working in currents of the order of milliamps, therefore, this device is widely used for the control of current dimmers.

The dimmer can be used in voltages of 127 v and 220 v, the most important point in this electro-electronic device is that the electrical losses in the current control and modulation are very small, which does not occur in equivalent devices that do not use the same solid-state technology. as, for example, devices based on rheostats that have the principle of resistance variation.

The most common type of TRIAC control for the dimmer

We can control the start of the conduction of a dimmer, applying a pulse at a pre-determined point of the alternating current cycle, that is, we choose a moment in the instant of an alternating current wave, thus controlling the percentage of the cycle that will be feeding the load, this control method is known as a phase control.

The main application of this type of control in low-power TRIAC is its use in power controls for dimmer lamps, speed controls for fans, among others.

However, when used with inductive loads, such as electric motors, it is necessary to ensure that the TRIAC is switched off correctly, at the end of each electrical supply semi-cycle or we lose a lot of power and torque at the end of the motor shaft, thus dimmers are not advisable to drive and control motors with high torque and requiring greater power.

Solid-state dimmer for lighting application

Applications for the solid-state dimmer?

Dimmers are used in the electronics industry, with the function of controlling the flow of electrical current in the circuit, varying the intensity of the same, when we exercise this variation in an electrical circuit, consequently, we vary the power consumed in the load.

As we have already discussed, the component responsible for this function is the TRIAC, which, through a current applied to the gate, allows it to control and modulate the load supply current.

The working principle of a solid state dimmer is to control the conduction angle of the Triac, when we fire, that is, we switch the triac at different points of an alternating sine wave, it is possible to apply different currents of current to a load, when this occurs we proportionally apply different powers to the load.

This way, when we perform a trip at the beginning of the semi-cycle, the load will absorb more electrical power, if the trip is carried out at the end of the semi-cycle, the portion of electrical power absorbed by the load will be less. Between the maximum and minimum points of an alternating electric current, we can linearly vary the power applied to the load, which makes the solid state dimmer the best solution for luminosity control.

Is the LED lamp compatible with the dimmer?

To apply the dimmer to modern lighting circuits, we must first be aware that not all current LED lamps support this device. Dimmers for LED lamps are actually a PWM modulation circuit as discussed earlier, most LED lamps (usually the cheapest) are not dimmable because they perform the transformation from AC to DC internally so they do not will respond to the variation of the PWM circuit, only when the circuit makes the complete wave possible the lamp will ascend.

For this type of application we need to purchase led lamps that support the application of dimmers. To do this, look in the manufacturer’s packaging for the technical description that informs you if the lamp can be activated using a dimmer, we often find the word DIM on the packaging, which means that the lamp is dimmable.

The advantages of LED lamps are their greater emission of heat in the environment, due to this they are widely applied in lighting sensitive or colored pieces of decoration, in addition to being even more economical when applied to dimmers generating significant savings and high return on investment.

Led lamps for use with dimmer drive

How to install the dimmer?

To install a dimmer, first make sure that the electrical circuit is de-energized. To do this, turn off the circuit breaker on the switchboard. After performing the described care, a specialized professional is not necessary to perform the installation of a dimmer, it is a simple installation circuit.

First just remove the switch (old), disconnect the wiring and connect the wires of the switch, on the dimmer, don’t forget to observe the color orientation according to the voltage of your residence. Generally for 127 V, the phase is red, in the return the phase is yellow, isolate the blue, in case the voltage is 220 V, the phase is red and blue, in the return, we use the yellow cable.

If, by chance, the phase is not identified, install it randomly. If the positions are reversed, this will not damage the device. If the installation does not work, change the order. Now just test and enjoy the lighting control in the room.

If you still have doubts we offer a video with a step by step to install a dimmer, following the tips presented you will have no major problems.

We can see in this article that not all led lamps are compatible with dimmers, so we need to choose carefully to opt for dimmable lamps, these lamps support the application of dimmers. We present a widely used dimmer type that uses the TRIAC a semiconductor as its main control device to perform the variation of the luminosity in the lamps, through the switching of the alternating current.