Through hole. 20x80mm 2.54 pitch
I could go ahead and order the necessary components. Lmk what they would be. I have bc547,bc548, and bc327
See updated schematic below.
I've redesigned the timer pulse circuit using a BC327.
I've also shown an "Alternate Input Circuit" that will compensate for the 4v input signal. It's basically two BJT switches.
The second BJT inverts the voltage level so that a positive pulse in will produce a positive pulse out. The output of this circuit would connect to the juction of C1/R8.
I haven't tested the Alternate input circuit but it should work. Other than that, the rest of the circuit should be good to go once you've tested.