PWM dimmer: this is how you dim LEDs correctly
PWM dimmers are used for brightness control and color setting of LED modules (e.g. LED spots, LED strips). If you want to dim LEDs professionally and sustainably, the variant with reducing the voltage is quickly eliminated! It not only reduces the brightness, but also the forward voltage of the LED. However, this also changes with the temperature and the result is an unstable system. Even the light color of the LED changes with the current. As a result, you have different colors.
The human eye is a "sluggish system", it reacts relatively slowly to changes in light and it is precisely this effect that PWM dimming makes use of. Put simply, the light of the LEDs is switched on and off very quickly with this variant and our eyes detect the mean value here. The advantages are obvious: no change in the light color, no change in the flow voltage when the brightness is reduced.
Pulse Width Modulation (PWM)
With PWM (= pulse width modulation), a fixed frequency is used (e.g. 1000Hz, i.e. switched on and off 1000 times per second). The desired brightness is set with the ratio of pulse (switched on) and pause (switched off). However, it is essential to ensure that the basic frequency is selected high enough so that no flicker (= flicker) can be perceived subconsciously (flicker index). By the way, cameras see this flicker because they work much faster than the eye. The frequency of our PWM dimmers can be set here by the customer himself and is selected to be sufficiently high. Do you need LED dimmers for photo and video productions? Then contact us, because we have special software variations with adapted frequencies in the kHZ range!
PWM dimmers are very efficient as they disconnect the circuit during the break time. They can therefore be viewed as almost loss-free!
Phase angle control with 230V dimmer
Halogen lamps, light bulbs and low-voltage lighting (with a transformer) can be dimmed perfectly with phase control. Here the first part of every sine half-wave is cut after the zero crossing. In other words, at this point in time the light source is disconnected from the mains.
Depending on the set dimming value, it is switched on with a time delay until the next zero crossing. Due to the rapid increase in current, the dimming form cannot be used for capacitive loads!
It is essential to observe the operating instructions for the respective product to be dimmed! There it is noted whether it is suitable for trailing edge and / or trailing edge.
Phase control with 230V dimmer
The trailing edge control works in exactly the opposite way. When the zero crossing is switched on and after reaching the desired dimming level, the current flow is blocked until the next zero crossing. Trailing edge control is mostly used with LED light bulbs and filament light sources.
This form of dimming is not to be used for inductive loads (e.g. transformers), as the abrupt shutdown would result in high voltage peaks.
It is essential to observe the operating instructions for the respective product to be dimmed! There it is noted whether it is suitable for trailing edge and / or trailing edge.