Here is the circuit for the 555. Use the 1Hz setting as it goes from 1Hz to about 8Hz via the pot. **broken link removed**
Next you have to put the 555 on a 12v supply. Use a resistor and zener diode as the voltage regulator to generate the 12v rail. Then you have to add the MOSFET to the output. Just connect the MOSFET to pin 3 via a resistor, say 470R.
Next you have to put the 555 on a 12v supply. Use a resistor and zener diode as the voltage regulator to generate the 12v rail. Then you have to add the MOSFET to the output. Just connect the MOSFET to pin 3 via a resistor, say 470R.