The presence of electric lighting in a modern apartment is as obligatory as the front door and glazing of windows. Different luminaires are not always required to work in the mode of creating a luminous flux of maximum brightness. There are two main ways to accomplish this. The first one is based on the use of table lamps, sconces and bedside lamps, the second is based on dimming. The dimmer that implements the second possibility is designed as a regulator, Figure 1, with which you can set the required brightness of the light source.
Various types of lamps can be used for lighting: incandescent, fluorescent and LED, and the latter are rapidly gaining popularity due to their well-known advantages. At the same time, not all types of LED lamps are compatible with dimmeters.
How the dimmer works
Any dimmer reduces the effective current through the source. This can be done in various ways. The first of these is voltage reduction, for example, using an autotransformer. The second method is based on changing the duration of the AC voltage supply to the lighting source without changing the maximum (amplitude) value.
The dimmeter uses the second principle, actually cutting off the current for a part of the period using a semiconductor key element, Figure 2. Moreover, depending on the version, this procedure is implemented in the first or second half of the alternating current half-wave. Sevenistor dimmeters control the brightness of the cutoff current in the first half of each half-wave, transistor ones - in the second.
The peculiarity of the interaction of the dimmer with the LED lamp
The LED lamp, similar to a traditional incandescent lamp, to ensure interchangeability along the base, Figure 3 is supplied from the mains with an alternating voltage of 220 V. The structure of the lamp includes a rectifier with a stabilizer, which convert alternating current into direct current, which is necessary for the operation of semiconductor crystals of LEDs.
The electronic filling of the lamp does not function normally in all cases with a non-sinusoidal current taken from the output of the dimmeter, and it may also be very sensitive to cutoff not in "its" part of the half-wave up to failure or damage to the dimmer itself due to the reverse effect on him.
The first part of the problem is solved by separating them from the entire set of LED lamps initially dimmable varieties, which is separately indicated by the inscription or the "dimmable" icon on the package, Figure 4.
Unfortunately, the industry has not yet developed standardization by the type of regulator, the industry has not mastered the serial production of lamps that are invariant to the performance of this element, and compatibility tables by manufacturer and type unknown. Therefore, the easiest way to at least partially solve this problem is to buy LED lamps in the store where the dimmer was purchased.