Qui trovi alcuni schemi:
https://www.google.it/search?q=ne555+touch&safe=active&rlz=1C1AOHY_itIT708IT708&espv=2&biw=1302&bih=839&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiL3fPIqZnPAhWJ7RQKHcXcBsQQsAQIGw&dpr=1