555 fading in&out if possible with pwm & led array

Question

i'm new here and also in the electronics world so pls be patient with my ignorance.

I's now months that i'm fascinated by the 555 timer. The stuff you can do with such a tiny thing is impressing.

As you can immagine i already tested most of the http://www.555-timer-circuits.com/ circuits, and also from other sites. And again ... wow!

Anyway, you know, reality is cruel.You never find what you really need.

This maybe simple for you, but for me it's a nightmare.

What i'm trying to do:

A Monostable 555 timer circuit

What should it do:

1. Triggered by a switch, sensor (PIR) fade in 2-3s
2. stay high for 1-3min *
3. fade out for 2-3sec

A simple light timer for the stairs, right??? NO

What it does:

1. Triggered by a switch, delay for 1-2sec
2. It fades in for 2-3 sec
3. It stays high

This is where i'm stuck atm.

But thats not all, i would like to attach mosfets or npn transistors delayed by another 100-300ms those driving a led strip of 3 leds and triggering the next one. Each strip is a stair (or step???).

I made this circuit knowing nothing and don't looking to much about if its correct because of the fact that i could use maybe npn transistors,pnp, or mosfets for this setup. using npn transistors would be cheaper but i would need to take the current from somewhere else to trigger the next one as i lose 0.7v at every gate.

^{simulate this circuit – Schematic created using CircuitLab}

A. So is there something that would delay each step at about 200-300ms or less?

from what i read about electronics i could use capacitors. but the capacitor needs to be small as it has to fit in a tiny place over the stair so 1cm * 2cm * 5cm max I guess it needs to be a big capacitor to delay 200ms or even 100ms?? are there other components that i'm not aware of that could create a delay?

each step could have his own 555? but thats $$ and probably the worst approach?

B. naturally i also need to solve the main problem, fading out the output of the 555 after 1min or so.(monostable) it's useless if i post my circuit for the fading led as there are hundreds with a simple google search and i really don't understand them all.I use a 220uf,20k and 100k i think, a npn 2N3904 to create the fading effect. but its not working correctly.

Everything could be done easely with microcontrollers, but i really like to understand more about ic's and electronic in general.

Notes: The whole question is based on the naive idea of a fade in effect. i didn't event thinked about the fade out effect result in the array. It probably would disastrous. So my first guess is to put one 555 at the base of the stair and one on top. Both ends have triggers, and both circuits flow in a different direction once activated. But that is another sotry.

Answer 1

Try connecting a slow monostable 555 oscillator to a simple, shift register frequency divider. This way you can shift the pulses in and they will stay on until the shift register is cleared.

Learn more about shift registers here:
http://www.allaboutcircuits.com/vol_4/chpt_12/1.html

Shift Registers as frequency dividers: (Not nearly as hard as it looks BTW) http://www.allaboutcircuits.com/vol_4/chpt_12/6.html

Using shift registers would eliminate the need for multiple 555 timers in your circuit and could greatly simplify the design because there is a constant time interval between lights lighting up.

I hope this solves your challenge!