Any text describing NE555 timers will have several ways to achieve this goal. Total parts cost around a dollar or two.

I'm not at home this week, so I can't quickly give you the exact title and author, nor a specific circuit.

This simple SCR gate drive circuit could be sufficient. Values are just initial suggestions.

That's simple enough, but you need a SPDT switch to discharge the capacitor when power is removed, and possibly a diode in parallel with the resistor to discharge quickly, if the off time can be very short.

Yup! If wired as shown, cap needs discharge path. Assumed load on 24Vdc would be enough, otherwise additional R is needed. More likely PS is switched from line side. Cap discharge could then occur through PS, load, or additional R.

I just used a design in this link just what you are talking about. Run it at 5V and adjust the timing capacitor works good I tested it. Here is the link: http://www.kpsec.freeuk.com/555timer.htm

Good Link!

Guys , thanks alot for the information. Really appreciated your ideas.