The 5V power supply is suitable as a bell transformer for operating surveillance and access systems, door openers, intercom systems, bell systems, etc. With a width of 18 mm, it is particularly compact and can be quickly and easily mounted on a DIN rail with a hat profile using a click system, for example, in a control cabinet. The 5V LED transformer offers high reliability and stability with an input voltage range of 100-240V AC at 50/60 Hz. The LED driver features a variable DC output voltage of 4.5-5.5V, as well as high efficiency and low no-load power consumption. The switching power supply is particularly safe thanks to overvoltage, overload, and short-circuit protection, IP20 protection class, and safe electrical isolation according to protection class II. The 230V to 5V transformer with passive convection cooling is connected via touch-protected screw terminals. The LED indicator on the DIN rail transformer DR-12-5 lights up continuously during operation.