Timer 555 bistable – alternative 1

This example of a flip-flop circuit is made without additional electronical bricks. You can set the SET-signal directly to the trigger input. Here a switching of the output voltage occurs, when the voltage at the trigger input falls below 1/3 of the supply voltage. The SET-signal is reset, when the reset input is connected to ground. When pressing the upper left push button, the red LED turns off. All states are stored to the state of the beginning until an alternative input is done.