555 monostable triggered with pulse train

[boylesg]

How is this supposed to work again?

The on time of the pulse train has to be less than the on time for the monostable 555?

 

[BradtheRad]

A downward-going transition triggers pin 2.
It can return upward anytime regardless whether the output is high or low.

Try adjusting the capacitor values in this schematic. A 555 IC operates as a monostable (one-shot). It is triggered by a pulse train from another 555.

https://tinyurl.com/b6tnew8