Hi, I have used NE556 to make this 556 timing flasher many times and it always works. I made this triple with NE556, which can make it not flash! Put the LM556 in its place and it works perfectly. I have never done this before, but put a 0.01uF to Vcc on #3 and #11 and #4, but there is still no time. What’s really strange is that I used LM556 two weeks ago to build one on both ends (think it was NE556) and the NE556 in the middle. They all worked well, I don’t understand! I think NE556 and LM556 are interchangeable.
Reference: https://www.utmel.com/components/lm556-dual-timer-circuit-application-and-datasheet?id=170