How to remove the flickering of LED lamps: in the off state and during operation, how to fix the problem

LED lamps, being more advanced and economical lighting devices in comparison with incandescent devices, are not without certain disadvantages. One of them is blinking. To remove the flickering of LED lamps, you do not need either deep knowledge of electrical engineering or significant financial costs. It is enough to understand the principle of operation of the device, know the causes of flickering and be able to use a soldering iron.

The principle of operation of the LED lamp

Flickering not only creates certain discomfort for the eyesight and the human nervous system, but also negatively affects the lamp itself, significantly reducing its service life. To fix the problem, you need to know the device of the LED lamp.

The most popular driver is a device designed to convert alternating current with a voltage of 220 V, which is fed to its input, into a direct current with specified parameters depending on the specific type lamps. For this, a diode bridge and an electrolytic capacitor standing after it are used, which acts as a smoothing filter. The output voltage is smoothed and stabilized, for which a corresponding electronic circuit is provided in the driver design. Next, voltage is applied to the LEDs.

Flickering lamp off

The most common cause of flickering is the use of a backlit switch. It is important to know that in order to implement this function, a low-power neon lamp is provided in the design of the switch, which is connected in parallel with the on / off button of the LED lamp.

When the device is off, the current flows through the backlight and then goes to the driver input, and through the diode bridge to the smoothing capacitor, which is gradually charged. As soon as the potential difference at its input and output reaches a certain value, the stabilization circuit is triggered, and voltage goes to the LEDs, forcing them to work for a split second, during which the capacitor has time discharge.

There are several ways to remove the blinking of an LED lamp, each of which has its own advantages and disadvantages.

Removing the backlight

The easiest way - remove the backlight bulb. Unfortunately, it is not suitable for all switches: there are modern models in which this is not possible. In addition, sometimes a backlight is needed: it makes it possible to quickly find a switch in a dark room.

Hard connection

The backlight lamp is connected independently of the LED lamp to the phase and neutral wires. So it will work constantly, regardless of whether the lamp is on or not, and the lamp itself will forever get rid of flicker.

The disadvantage of this method is that an additional wire will be required, which is not always convenient.

Replacing a conventional switch with a straight through

In this case, in one position of the switch, the lamp will work, and in the other position, the backlight will light up. The method will require the purchase of a switch, but completely eliminates the possibility of flicker, even if its cause is not related to the backlight.

Bypass luminaire

That is, connecting a load with a lower resistance in parallel with it. In this case, the main current will go through the load, and the current that remains at the lamp's share is not enough to charge the capacitor.

As a shunt load, you can use:

1. Simple incandescent light bulb. The method is suitable for the case when there are several lamps connected in parallel, for example, in a chandelier: instead of one of them, an ordinary lamp is simply put. The way to solve the problem is simple, but it has drawbacks: in this case, you can forget about saving energy consumption. In addition, modern lighting devices are not always designed for such an accessory as an incandescent lamp that heats up to high temperatures.
2. Resistor with a resistance of 1 mOhm and a power of about 2 W. The resistor is heat shrinkable and connected directly to the junction box, between neutral and phase, parallel to the luminaire. The method has approximately the same disadvantages as in the previous case: it leads to additional costs of electricity, which will go to heating the resistor. In addition, it is unsafe for such a heat source to be present in the junction box near the wires.
3. Capacitor, the capacitance of which is in the range from 0.01 μF to 1 μF, and the voltage is 630 V. This is the most economical and safest way to bypass surgery. Firstly, being a reactance, the capacitor will not affect the meter readings in any way and, secondly, it will not heat up. The larger the capacitance of the capacitor, the more reliable the shunting, but with an increase in power, the size of the radio component also increases. A ceramic or paper capacitor is needed, electrolytic is not suitable, since they are susceptible to sudden voltage changes and can explode. If an electrolytic capacitor is chosen as a shunt, its voltage reserve should be large enough.

If flashes when there is no backlight

In this case, you should check if there are other wires in the same strobe, except for those that supply power to the LED luminaire. The fact is that a long supply wire can become a kind of antenna, and live wires lying nearby create a weak electric field. As a result, a voltage is generated at the contacts of the filtering capacitance, which leads to the switching on of the LEDs.

There is another reason why the LED lamp flashes when it is on, associated with wiring deficiencies: incorrect connection of the lamp to the network. It is necessary that the phase wire be connected to the switch, and the zero wire to the lamp, otherwise In this case, the circuit responsible for starting the lamp will be constantly at potential, and flicker will not will succeed.

You can find out where which wire is connected using a phase screwdriver with a light indicator.

Reasons when the lights are on

It is more difficult to determine this defect visually, since it is not always visible to the eye, nevertheless changes in brightness have a detrimental effect on vision and on the state of the psyche, leading to insomnia and rapid fatigue. In addition, flickering will cause the lamp to fail quickly.

There are two ways to find out why the LED lamp flickers during operation:

1. Pencil test. This will require an absolutely dark room in which only the tested lamp works. You need to quickly draw a pencil in front of it: if there is a solid trace, there is no pulsation, an intermittent trace indicates that the lamp is flickering.
2. Video camera testsuch as a mobile phone. You should stand at a distance of a meter from a lighted lamp and point the camera at it: if it flickers, then dark stripes will appear on the display.

There are several reasons for flickering when the lamp is on.

Poor quality lighting fixture

Since it is impossible to convert an alternating current into an ideal constant current, the inevitable voltage drops, entering the LED contacts, lead to changes in the brightness of the lamp glow.

If these changes are insignificant, that is, the ripple coefficient does not exceed 20%, they are not perceived by the eye, otherwise it is seen that the lamp is flickering.

The better the lighting fixture, the less chance of flickering. In cheap Chinese lamps, it can be caused by a too high value of the ripple coefficient, which exceeds the permissible standards.

The more perfect the driver, the less ripple, and, accordingly, the smoother the lamp will burn. Cheap products use low-quality radio components that are not able to cope with the task at hand. In this case, flickering can be eliminated only by connecting the luminaire to a DC power source.

Small capacitance of the smoothing capacitor

This is a common case of a poor quality driver whose filter does not cope with the ripple smoothing function, and AC current is partially applied to the LED contacts, causing them to periodically increase the brightness glow. The defect can be corrected by replacing the filter with a larger capacitor.

The reason may be a mismatch between the voltage in the network and the parameters necessary for the lamp to work correctly, or sudden voltage surges. In this case, you will have to change the lamp itself to a better device that has protection against voltage changes or install a stabilizer.

Dimmer incompatibility

This refers to a device that allows you to change the brightness of the glow. Not all LED luminaires are dimmable; it is also possible that the lamp is incompatible with the dimmer of a particular model.

To diagnose this cause, you need to turn on the lamp directly. If it works correctly, several options are possible.

The lamp connected to the dimmer will flicker if:

1. The calculated load of the dimmer required for its correct operation is greater than the load that the LEDs can provide. In this case, an additional load can be connected to eliminate flickering.
2. The dimmer is overloaded. That is, the maximum load for which this device is designed has been exceeded. This is possible when several lamps are connected at the same time, the total power of which is greater than the allowable for the dimmer.

When calculating the number of lamps that can be connected to a dimmer, many inexperienced users simply divide the dimmer power by the power of one lamp. This is absolutely wrong, since this method of calculation does not take into account the strength of the inrush current and its repeated surges every half period. As a result, the device becomes overloaded, which leads to flickering.

To normalize the operation of the lamps, you can turn them on directly, without a dimmer, replace it with more powerful device or divide the lamps into separate groups, using for each of them its own dimmer.

Also, flickering can be caused by:

1. Defective switch (for example, insufficiently tight contacts).
2. Illiterate wiring.
3. Incompatibility of the socket into which the lamp and its base are screwed.
4. Damage to the driver.
5. End of lamp life.
6. Damage to the luminaire itself, possible if the temperature is too high near its body, strong vibration created by the ventilation system or operation climatic technology, high humidity, contamination of the room with suspensions of aggressive substances that destroy the elements of the lamp, as well as dropping the lamp.

Having dealt with the causes of flickering, you can use a soldering iron to fix the problem using any of the methods suggested above.