Any LED strip can flicker or not. It depends on how it is operated.
How does this work?
- If we observe a 230 Volt LED strip, it is marked with polarity.
- The power connector usually contains only a rectifier (GBU810), so it is unfiltered, and we only have a pulsating direct current. As a result, LED strips operated with this setup flicker badly. Therefore, I only recommend using it for outdoor decoration.
- If we want to operate the 230 Volt LED strip with a controller that can handle low voltage LED strips, we have the option. For example, such controllers are the Skydance S3 or its counterpart, the Optonica 6397. However, these controllers do not solve the flickering problem.
- The direct current produced by these controllers is also a pulsating current made of half-sine waves and not a stabilized DC230 Volt. Therefore, the LED flickers at 100Hz, making the 2kHz flicker-free PWM control practically useless because it is based on 100Hz half-sine waves instead of stabilized voltage.
- Therefore, it can be very uncomfortable for those sensitive to it. Of course, if we provided these with stabilized 230 Volt DC power supply, they would not flicker at all, but they were not designed for that, and the power outlet does not supply direct current.
- Low voltage LED strips (5, 12, 24 Volts) are designed for DC operation and should not flicker when powered by DC, but…
- But if we want to dim them, mix colors with RGB strips, or create other lighting effects, they do flicker. However, much more subtly than the 230 Volt ones. What is the reason?
- To reduce the brightness of an LED strip, it does not happen by reducing the voltage as some might think – no! A 12 Volt LED still receives 12 Volts even when the brightness is set to a minimum. The brightness control is done via PWM (Pulse Width Modulation). This means that the DC current is interrupted at a frequency higher than 50Hz (300Hz or more with Miboxer, Skydance 500-750Hz). So, when set to half brightness, the LED alternates between receiving current and not receiving current 300 times per second. We change the ratio of the two with PWM control, called changing the duty cycle of the signal, to adjust the light output, i.e., dim the LED strip. Therefore, at maximum brightness, the duty cycle is 100%, and the LED does not flicker. But when set to minimum brightness, which can vary by dimmer, it is easy to see that at 1%, the LED receives no current 99% of the time. Although this is divided into 300 parts per second, sensitive eyes may notice some flickering at such low brightness.
- There is already a solution for this too! Some LED strip controllers allow a higher PWM frequency to be set. Some Skydance controllers can be set to 2kHz, while some Miboxer controllers can be set to 8kHz PWM signals.
- With RGB lighting, if we only illuminate with one of the three primary colors at maximum brightness, there is no flicker. But if we mix purple, 50% red and 50% blue, it is clear that both the red and blue diodes only receive current 50% of the time, and yes, this happens at at least 300Hz. However, if we want to add just a little blue to red, the blue may only light up 1% of the time, while the red lights up 99%.
What can those who are bothered by this PWM control flickering do?
- Do not use dimming. If you still want to choose between multiple brightness levels, for example, stick 3 LED strips side by side and operate them with a 3-way chandelier switch. This way, even if you stick strips of the same power, you can choose from 3 different brightness levels.
- In the case of RGB LEDs, operating the three colors with a 3-way chandelier switch, you will have to settle for 7 color variations, of which yellow will most likely be greenish-yellow, as the green on RGB strips is almost always stronger than the red. In addition, you cannot dim the brightness, with red being the weakest, followed by blue, green, yellowish-green, purple, turquoise, and the strongest being cool white.
- If you opt for variable colored lighting, you must accept the flickering caused by PWM control for those who are sensitive to it. However, it is quite unlikely that a person sensitive to all types of flickering would specifically want continuously changing colored lighting.