I have made a monostable multivibrator and an astable multivibrator using 555 timers using a popular circuit design found on the web.
The monostable (out via pin 3) is used to control the astable (via its pin 4).
When I push the momentary switch on the monostable the astable should flash two LED’s until the mono times out. And it works well if I use seperate power supplies to each multivibrator. (The zero volt rails are commoned together).
However, when connected together to a single power supply as in the circuit below, the mono will no longer time. Holding the switch closed will operate the astable ok until the button is released.
They only seem to work together if I use separate power supplies for each multivibrator.