DESCRIZIONE
The present invention relates to a method for providing a time varying supply voltage from a source of electrical power to a light source, the method comprising the steps of providing a first supply voltage in a first time period to the light source, determining a first available voltage level from the source of electrical power from a decay rate of a first control signal, and providing a second supply voltage in a second time period to the light source, the second supply voltage being a PWM supply voltage having a duty cycle being dependent on the first available voltage level. The present invention further relates to an electronic system for carrying out the method, and to a lamp for a life jacket or raft including such electronic system.