sink 21 being illustrated in fig3 however the same applies to the switch that is to say only the first switch 31 for the first light source 11 is illustrated in fig3 in the second embodiment of the invention the light sources 11 12 are driven in a similar manner to that in the first embodiment of the invention by means of the regulator 60 and corresponding current sinks 21 therefore the regulator 60 with the first regulating component 61 and the second regulating component 62 the input 65 of the light sources 11 to 15 the regulating input 51 and the adder 50 u2032 are again illustrated furthermore the measuring means 40 and the control means 50 are likewise illustrated in the left hand part of fig3 there are differences with regard to the measuring means 40 and the evaluation of the individual light emitting diode strands in the second embodiment of the invention in contrast to the first embodiment of the invention the functions of the voltage amplification regulation means 50 u2033 according to the first embodiment of the invention are also undertaken by the control means 50 for this purpose the control means 50 has an output line 52 which acts on the adder 50 u2032 with the result that the voltage needed to stabilize the control loop is.