blink_first_try.ts

const show$ = Observable.timer(0, 1000);
const hide$ = Observable.timer(750, 1000);

const blinker$ = Observable.merge(
  show$.mapTo('showing'),
  hide$.mapTo('hiding')
);

blinker$.subscribe(value => {
  // Let's assume the "element" variable holds a reference to the
  // element we want to show or hide.

  if (value == 'showing')
    element.style['visibility'] = 'visible';
  else if (value == 'hiding')
    element.style['visibility'] = 'hidden';
});