new realy from 500ms to1s contating time

dear
any one can helpme to make a new realy that must contact atleast 500ms to 1s
after that time i need relay cut off automatically,realy coil voltage i like to use dc5volt.supply coming from ac to dc converter.also i like to use a regulator for 5volt supply.if i turn off ac power supply relay must be reset,then affter i turn on ac suply switch relay have to contact only 500ms to 1s.
every time i turn on ac supply,5volt dc coil isolated relay must start cotact only 5ooms to 1s.i expecting your good response.
please informe me which is the best isolated relay in 5volt.

The attached is a relay monostable that will close the relay contacts for a brief period when +5V is applied. When the +5V is removed it will be reset, ready for another pulse when the +5v is reapplied. The pulse length is dependent on the value of C1, the coil resistance of RLY1, and the drop-out voltage of RLY1.

Ken