Analogue dimming covers all dimming systems that don’t transform the dimming signal into bits and controls the lighting in analogue manner.
Phase dimming systems dim the lights by altering the supply voltage.
Leading & trailing edge dimming
Before LEDs, we used to dim halogen lamps with wall dimmers. We can still use these kinds of dimmers. But dimmer, driver and LED-module must be compatible with each other.
This type of controlling is accomplished without any need for an additional control wire. It involves connecting a dimmer in series between one of the mains wire and the equipment.
The dimmer cuts part of the mains voltage sinusoidal waveform to a greater or lesser extent in order to dim luminous flux even from 1% to 100% (this value depends on dimmer and driver).
Depending on how driver makes the mains voltage cut, it is possible to distinguish between two types of dimming:
Dimming cut-off in the wave on its ascending side, from the beginning (phase cut-off at ignition). This is traditionally used in halogen lamps supplied through electromagnetic transformers.
Dimming by cut-off in the wave on its descending side, from the end cutting backwards (phase cut-off at switch off). And this way of dimming causes less interferences than leading-edge dimming.
There are dimmers and equipment that support both types of dimming, and others that support only one type.