Ok... so let us consider your measured t (PW) as the given data and find out C that 555 IC really sees.
I assume you can verify that RA has indeed the value 10K.
I just noticed the real values of RA and C... sorry
C_tot = T/R/ln [ Vcc/(Vcc-Vctl) ]
It seems that C_tot (seen by 555) is about 12 nF (sorry this is wrong
)
14.05nF @4V
14.72nF @5V
14.97nF @6V
15.45nF @7V
15.83nF @8V
So I think we have to add another factor in the C formula to include the Vsat of pin 7:
Vc(t) - Vc(0) = [ Vmax - Vc(0) ] * [ 1 - e^( -t/RC ) ]
Where
Vc(0) = Vsat (at time 0)
T = RC * ln [ (Vcc - Vsat) / (Vcc - Vctl) ]
It is better to isolate Vsat first.
Vsat = Vcc - (Vcc - Vctl) * e^(T/RC)
This didn't work too :sad:
If this happens to me... I won't sleep till I get the missing keys :smile:
I am not sure how much the delays from trigger to output (low to high) and from Vc = Vctl to output (high to low) contribute on the measured pulse width.
In any case, since we have 12V, I prefer to charge C with constant current instead.
I think you already saw how to do it on the next paragraph "Linear Ramp".