Timer astable

The operational amplier is also used to generate oscillations. The „clock“ is a classic series circuit of capacitor and coil that is connected to the plus input and implements the feedback of the output to the input. The amplitude of the output voltage is determined by the potentiometer at the negative input and the amplication factor (5.7) of the resistance ratio of 4.7k to 1k. The yellow LED lights up only, when the wiper of potentiometer is in the right range clockwise from the start.