Car light News
News Classification:Driving LEDs on mains
CAR LIGHTS FROM CHINA, BEST PRICE/QUALITY RATIO!
Driving LEDs on mains
LEDs are low-voltage devices, and have very low dynamic resistance, with the same voltage drop for widely varying currents. Consequently they cannot connect direct to most household sources without causing self destruction. A CR dropper (capacitor & resistor) followed by full wave rectification is the usual ballast with mains driven series-parallel LED clusters.
A single series string would minimise dropper losses, but one LED failure would extinguish the whole string. Paralleled strings increase reliability. In practice usually 3 strings or more are used.
Operation on squate wave and modified sine wave (MSW) sources, such as many inverters, causes heavily increased resistor dissipation in CR droppers, and LED ballasts designed for sine wave use tend to burn on non-sine waveforms. The non-sine waveform also causes high peak LED currents, heavily shortening LED life. An inductor & rectifier make more suitable ballast for such use, and other options are also possible.
