Why Do Some Lights and LEDs Flicker?
Flickering lights and bulbs can often be a source of frustration, especially when it comes to LEDs that are known for their energy efficiency and longevity. This phenomenon can be attributed to a variety of factors, primarily the interaction between certain light dimmers, the type of light source used, and the electrical supply.
Understanding Dimmer Lifespan and Compatibility
Dimmers are designed to work most effectively with incandescent bulbs, which operate by gradually reducing the voltage supplied to the filament, allowing it to gradually dim. However, these dimmers can sometimes cause LEDs to flicker, which is a significant issue given the prevalence of LED lights in modern homes and workplaces.
In homes where incandescent bulbs have been replaced with LED lights, the dimmer switches used to control the brightness may not be compatible. This incompatibility can lead to flickering, particularly with LED lights that do not have a built-in driver. Here, the dimmer switch attempts to regulate the power supply to the LED, but it struggles to work effectively because LEDs require a constant current to produce light rather than a variable voltage as incandescent bulbs do.
To address this issue, replacing your dimmer switch with one that is compatible with LED lights is a necessary step. Additionally, ensure that the LED lights themselves are dimmable and have the appropriate drivers installed. This will significantly reduce or eliminate the flickering issue.
Electrical Supply and LED Behavior
When it comes to residential LED lamps meant to replace incandescent bulbs, the flicker effect is often due to the alternating current (AC) supplied by the electrical system. AC alternates between a positive and negative voltage, typically 50 or 60 times a second (depending on the region). During this cycle, there is a point when the voltage is near zero, leading to no light emission. The human eye can pick up on this, particularly during blinking or movement.
In comparison, traditional incandescent filament bulbs emit light through thermal radiation, which is less dependent on voltage levels. LED bulbs, on the other hand, only emit light when a minimum voltage potential is present. Below that threshold, they cease to emit light, resulting in a noticeable flicker to the human eye, especially in high-quality COB (Chip On Board) LED fixtures that use a slow phosphor to help smooth out any fast flicker.
Direct Current and Pulse Width Modulation
When LEDs are powered by direct current (DC), the flicker effect can be attributed to pulse width modulation (PWM) techniques used to control light output. PWM involves using a constant voltage and varying the duration for which the voltage is applied, with the LED turning off completely for the rest of the pulse. These pulses can vary in length and frequency, from tens to thousands of cycles per second.
The higher the frequency used and the higher the duty cycle of each pulse, the less likely it is that any noticeable flicker will occur. For instance, in household appliances, a frequency of over 1000 cycles per second is typically used to ensure smooth operation. Lower frequencies can be more noticeable, leading to a visible flicker.
Conclusion
In conclusion, the flickering of lights, particularly LEDs, can be a complex issue influenced by dimmer compatibility, electrical supply characteristics, and the specific nature of LED operation. By ensuring that your dimmer switches are LED-compatible and that your LEDs are appropriately driven, you can significantly reduce or eliminate this issue, leading to a more pleasant and reliable lighting experience.
To ensure your LED lights are functioning optimally and to avoid flickering, consider the following tips:
Replace your dimmer switch with a LED-compatible model. Ensure your LED lights are designed to be dimmable and have the appropriate drivers. Use pulse width modulation (PWM) techniques at high frequencies (over 1000 cycles per second) for smooth operation.