delay-off bathroom fan

[goffery]

Dear friends,
I need help.
First, confession: My skills in electronics are rather poor.
Well, What I want to build is a times off delay for bathroom fan, frequently called extractor.
Originally, I had a fan with internal delay off control, but it went bad.
The fan is powered by 220V mains, through a relay from the 12V electronic circuit. The circuit is built around 4060 oscillator/counter.
The common wiring in Israel for these kinds of devices is a three prong outlet containing permanent phase and zero, plus switched additional phase (same phase), which is driven on when the lights are turned on, and turned off, accordingly when the lights are gone off (when the customer goes out).
Operation: as the lights in the bathroom switched on the fan goes on, and stays on as long as the lights are on. After switching the lights off, and after a preset duration (5-30 min), the fan turned off as well.
The main idea is that the controller is always hooked to mains supply, and the phase-on when light turned on, and then off provides the signal for clocking.
I tried on my own several configurations, with "beautiful" failures. For instance I thought of using logic "not" inverter on the delayed output (one-shot configuration) preset time, but the switched phase (bathroom lights) brings the reset to low, and resets the timer…
Many of you there have enough know-how and ingenious ideas as to how to work it out. Will you please enlighten me?
Thank you all in advance,
BTW: one important thing to remember. There is no momentary switch there to use for resetting. Only the three outlets: L (line) and 0, both permanent, and LT (switched line) witch turned the bathroom light, and delivers signal to the fan, and stayed on (latched) till tight turned off.
Yossi

[pebe]

The 4060 circuit is probably still the best way to go.

Originally, I had a fan with internal delay off control, but it went bad.

Which went faulty, the fan or the controller? If the controller, is it salvageable or repairable?