the amplifier input being further connected to a capacitor 14 in the feedback path of the schmitt trigger 12 a frequency determining component 15 in the form of a resistor is provided in parallel with the resistor 13 said component 15 being externally connected to the basic circuit 10 so that the user can set the fundamental frequency of the oscillator 11 by selecting an appropriate resistor further the basic circuit 10 comprises several outputs a1 a5 each of these outputs is controlled via a transistor t1 t5 which applies a negative pulse ground potential to this output when driven into the conductive state the transistors t1 t5 are successively driven by the oscillator circuit 11 wherein the transistor t1 supplies a pulse a pulse interval of the same duration occurs thereafter and the transistor t2 supplies a pulse etc a load l1 l5 in the form of an led is connected to each of the outputs a1 a5 all leds are interconnected at their other terminals and connected via a resistor 16 to the positive pole of a voltage source 17 whose negative pole is connected to ground potential when an output pulse ground potential occurs at one of the outputs a1 a5 the respective led lights up the circuitry described so far is known it provides pulses of identical durations at each of the outputs a1 a5 the pulses cyclically succeeding each other at the outputs a1 a5 and the output a1 being activated subsequent to the output a5 according to the invention a switch 18 is connected in.