Sometimes a 555 timer does not output a great square wave from 0-5 V. In this case, when using it as a clock source for a flip-flop, a bad 555 timer output can lead to missed clock pulses and seemingly strange behavior on the output. To correct this, use one or two Schmitt inverters (7414) …
I’ve decided to post a link to my blog. My goal is to start writing more about the digital logic and microcontrollers project that I work on, to act as help and inspiration for my students. Occasionally I also write about my other passion, which is flying airplanes. Don’t expect updates terribly frequently, however. 🙂