General information about dimmable LED transformers for the operation of LED retrofit lamps (low voltage, GU5.3, GU4, ..)
If dimmability is to be maintained, all three components must fit together. The LED lamp must be dimmable, the power supply unit 12V LED transformer must also be suitable for dimming, as well as be compatible with the leading or trailing edge dimmer. Since there is no standardized interface here, it is worth taking a look at the compatibility lists to avoid flickering, for example. In principle however applies that with this solution a compromise must be entered regarding dimming comfort. With this technology it is no longer possible to dim the usual dimming behaviour to just a few percent (100% - 1%).
For dimming via leading/trailing edge, use 12V LED transformers and AC (alternating current) lamps.
The reason for this is that the operating electronics of the dimmable LED power supply also require energy to generate stable LED current. Flickering or undefined shutdown is the result.
Accordingly, the operation of LEDs is increasingly based on pure LED solutions with Constant current sources. This in conjunction with controls via 1-10V, DALI, push-button dimming or via radio.
The right dimmable LED ballast for LED strips
When operating LED Stripes, on the other hand, there are now many possibilities using a 12V power supply. On our pages you will find a variety of suitable LED ballasts with different power ratings and control inputs, as well as dimming concepts. These are explained in brief below.
Dimmable LED 12V power supply and its variants
While incandescent lamps can be dimmed relatively easily by reducing the voltage, this is no longer as easy with LED strips. LEDs are electronic components, so-called semiconductors, and require a certain voltage to light up. Nothing happens below this threshold value and only at a certain voltage value does the brightness increase abruptly. For this reason it is done via a detour over a current control, realized over further electronic components. These convert the input voltage into an analog current for the LEDs, so that the following dimming variants are possible.
Variant 1 - Voltage variation
The LED operating device for e.g. 12V is reduced in the output voltage.
Variant 2 - PWM dimming
The operating voltage is switched on or off for different periods (Pulse Width Modulation).
The control gear must be aligned accordingly and this depending on various control options on the user side..
Possibility 1 - The transformer itself is conventionally dimmable.
Special dimmable LED transformers can be used with standard phase dimmers. These are often already available. Here the LED transformer is switched directly after the phase dimmer. The LED strips are then simply connected to the LED transformer. This solution is often used if only the existing three lines (L,N,PE) are available in the domestic installation. Disadvantage: Limited dimming range, as already known from retrofit solutions.
Possibility 2 - Transformer is dimmable via external control line
Some manufacturers offer LED transformers with an additional control input. The output voltage can be changed or switched via a control voltage such as 1-10V, a potentiometer, a DALI signal or a PWM signal.
The principles are different and depend on the respective type. This solution is also often combined with radio modules (e. g. Casambi).
Dimmable transformers are particularly suitable if the LED strips have only one light colour
Possibility 3 - Fixed voltage transformer with additional PWM dimmer
This variant offers maximum flexibility and is also suitable for retrofitting in existing installations. The additional PWM dimmer is installed between the power supply and the LED strip. The adjustment of the desired dimming degree is possible by many different ways (DALI, push button, 1-10V, radio, Bluetooth, Wlan with additional module). With this version not only monochrome, but also multi-coloured (DUAL-White, RGB, RGBW) LED strips can be controlled.
Possibility 4 - LED transformer 12V with integrated PWM dimmer
This is an LED power supply unit in which the dimming level can be set directly via the DALI or DMX interface. The 12V power supply unit is supplied directly with the voltage supply (230V). The LED strips are also connected to the power supply. The advantage here is that only one component is required for dimming. Control is via the integrated DALI or DMX interface.
Do not hesitate to contact our experts for LED strips. We will be happy to advise you.
