Oh, that explains the simulator crashing, but strangely enough it still worked on a breadboard giving me the delays i posted earlier.

Anyway, since i can't re-create the conditions without the logic gates, I may as well ask straight away.

Without the NOT gates, the LED stays on for about 11s, until the capacitor is charged sufficiently, and then goes off(well not actually, but becomes very very dim).

Is there any way whereby i can increase this delay period to more than 11s (well without increasing the capacitance over 4700u? Say double of it or 22s ?

I'm hoping for a mathematical approach to this because that's the part where I'm really clueless. I could just fiddle around with variables on the simulator and figure something out, but I'd rather not.

Could you point me in the right direction ?

Thanks.

EDIT: While my above queries are equally relevant, I wanted to add on to what i last posted.

I realized that this is what i had actually assembled on the breadboard, which seems to make more sense.

Now that i have that 10k resistor that pulls the input of the NOT gate to ground if there is no current, it seems to please the simulator as well....

Now, while I have not tested these exact values in the circuit myself, the simulator seems to think that with the 2.5M resistor, the LED stays on for about 4000 seconds.

With the 2.5M resistor, it stays on for approx 9000 seconds.....

Now there is a definite relationship between these variables but I know not the mathematics of transistors well.... How can i put this to paper and calculate a desired time period ?

Thanks !