Some lamps operate at a specific voltage, most commonly 12 V. Thus, they require a transformer upstream to adjust the mains current to their needs. This accessory is, among other things, necessary for LED strips as well as MR11, MR16, and G4 bulbs (range hood lighting, desk lamps, etc.).
Most often, this electronic accessory for lighting consists of:
- a transformer to convert the voltage of the current;
- a diode bridge to rectify the alternating current and convert it into direct current;
- a filtering capacitor to stabilize the output voltage.
When replacing a bulb, it is very important to check its compatibility with the transformer. Indeed, the electrical component:
- delivers a voltage of 12 V and displays a tolerance of plus or minus 5 V for halogen bulbs, thus providing a voltage between 7 and 17 V at the output;
- provides a voltage of 12 V with a tolerance of plus or minus 0.3 V for an LED bulb.
In general, the models currently offered:
- convert mains current (alternating current, marked AC) into direct current (marked DC);
- reduce the current voltage to 12 V and regulate it at the output;
- are only compatible with 12 V bulbs and spots.
It is important to know that:
- the integrated regulator ensures a continuous voltage of 12 V at the output (however, it is necessary to check the presence of this device through the description written on the packaging);
- some models produce alternating current (in 1% of cases);
- for most manufacturers, warranties applied to bulbs are only valid when the electronic accessory is compatible with the lamp.
To choose the right accessory, it is imperative to determine the appropriate power:
- by adding up the power of each bulb or by calculating the power of the LED strip based on its length (thanks to the power per meter indicated by the manufacturer);
- by taking a margin of 10% with respect to the evaluated power to avoid continuously exploiting the electrical component's capabilities to the maximum;
- by opting for a model with a power greater than or equal to the calculated value for the installation.
The transformer for lighting serves to convert the mains current according to the bulb's needs. The majority of models allow regulating the output voltage and improving the lighting system's lifespan.
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