Time delay relay?

I am in the process of hooking up a pair of strobe lights to my alarm.  Unfortunately the two strobes flash at the same time.  I would like them to flash alternately - similar to police lights.  Is there an easy way to put a delay into one of the stobes for like a half second.

I think all I need is a delay circuit, but I know nothing about that or where I could get such a thing.

Please help, this is the one thing keeping from finishing the project.

-ChuckD

use a  cap and a resitor to charge it. Find the min voltage needed to switch the relay.  

1 use 13vdc for your car and below values to the closes min turn on votage of the relay.

2  take your delay time divide buy the number next to the above value you used to find your min turn on.

3 take that value and divide by the cap value that will = the resistor value.

4 now paralle the relay to the cap and power it through the resistor from the output of the alarm

5 add more resitance for a longer delay use a pot to fine tune.

This should work